Co-reporter:Tianrong Zhan, Xiaolin Liu, SiSi Lu, Wanguo Hou
Applied Catalysis B: Environmental 2017 Volume 205(Volume 205) pp:
Publication Date(Web):15 May 2017
DOI:10.1016/j.apcatb.2017.01.010
•NiFe-LDH/NrGO catalyst was obtained via a one pot method by solvothermal reaction.•ORR and OER activities of NiFe-LDH/NrGO in alkaline media were firstly investigated.•NiFe-LDH/NrGO gives a superior ORR activity and stability involving the 4e pathway.•NiFe-LDH/NrGO also shows better OER activity with a 250 mV onset overpotential.It is a crucial and challengeable task to develop non-precious metal catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in energy storage and conversion systems. Herein, a facile and cost-effective strategy was employed to prepare the mesoporous nitrogen doped NiFe layered double hydroxide/reduced graphene oxide (NiFe-LDH/NrGO) nanospheres via an one-pot solvothermal reaction by using GO, protonated g-C3N4 nanosheets (p-CNNS), mixed metal salts and alkali as precursors in presence of surfactant. The doping of p-CNNS resulted in the superior ORR activity compared to pristine NiFe-LDH and NiFe-LDH/rGO. The ORR results demonstrated that the NiFe-LDH/NrGO hybrid involved a perfect 4e mechanism with better durability and methanol tolerance ability than commercial 20% Pt/C catalyst in 0.1 M KOH. NiFe-LDH/NrGO also displayed the excellent OER activity with a close onset overpotential to NiFe-LDH/rGO, but a more negative overpotential and a higher current density at η > 300 mV in the same alkaline medium. Overall, the outstanding catalytic performance toward both ORR and OER suggested that the NiFe-LDH/NrGO composite can be a new non-precious metal bifunctional catalyst in the related renewable energy fields.Download high-res image (224KB)Download full-size image
Co-reporter:Yongfang Zhang, Xiaowen Wu, Yuwei Mi, Haiping Li, Wanguo Hou
Journal of Physics and Chemistry of Solids 2017 Volume 108(Volume 108) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.jpcs.2017.04.018
•A hierarchical nanocomposite of (HCPT-Ch-LDH)@LS was constructed.•HCPT/Ch intercalated LDH nanohybrids were synthesized via a co-assembly route.•HCPT-Ch-LDH nanohybrids were modified by a liposome-coating strategy.•The (HCPT-Ch-LDH)@LS shows excellent water dispersity and stability.•The (HCPT-Ch-LDH)@LS exhibits enhanced drug sustained-release performance.A hierarchical nanocomposite of 10-hydroxycamptothecin (HCPT), a nonionic and lipophilic anticancer drug, intercalated layered double hydroxide (LDH) encapsulated in liposomes was constructed. HCPT molecules were first incorporated into sodium cholate (Ch) micelles, and the resultant negatively charged HCPT-loaded Ch micelles were then co-assembled with positively charged LDH single-layer nanosheets, forming a HCPT/Ch intercalated LDH (HCPT-Ch-LDH) host-gest nanohybrid. The nanohybrid particles were further coated with liposomes (LSs), gaining a core-shell nanocomposite, denoted as (HCPT-Ch-LDH)@LS. The so-obtained samples were characterized using TEM, SAXS, FT-IR, DLS, and elemental analyses. Special emphasis was placed on the effect of liposome-coating for the HCPT-Ch-LDH on its water dispersity and drug-release. The results showed that the nanocomposite has excellent water dispersity and enhanced drug sustained-release performance in comparison with the HCPT-Ch-LDH, demonstrating that the liposome-coating for drug-LDH nanohybrids is an effective strategy to enhance their water dispersity and sustained-release performances. This work provides an effective strategy for engineering of LDH-based delivery systems for nonionic and lipophilic drugs.A liposome (LS) coating strategy was employed to modify 10-hydroxycamptothecin/cholate (HCPT/Ch) intercalated layered double hydroxide (LDH) nanohybrids. The resultant (HCPT-Ch-LDH)@LS nanocomposites exhibited excellent water dispersion stability and good drug sustained-release performance.Download high-res image (258KB)Download full-size image
Co-reporter:Jie Xu, Huanhuan Deng, Jiaxin Song, Jun Zhao, Li Zhang, Wanguo Hou
Journal of Colloid and Interface Science 2017 Volume 505(Volume 505) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jcis.2017.06.080
Hierarchical flower-like Mg2Al-Cl LDH microspheres were synthesized using a reverse surfactant-free microemulsion (SFME) route at a low temperature (∼25 °C), and characterized by XRD, TEM, SEM, FT-IR, TG, N2 adsorption/desorption, and elemental analyses. The SFME used consists of n-hexane, isopropanol, and water. The so-obtained flower-like microspheres are constructed with LDH nanosheets with ∼10 nm thickness. After destroyed by calcination, their crystal structure and flower-like morphology can be reconstructed by rehydration. The flower-like LDH and its calcined product (CLDH) have large specific surface areas being ∼84.3 and 163.9 m2 g−1, respectively. The sorption of methyl orange (MO) on the LDH and CLDH were determined, showing high MO sorption capacities of ∼559 and 1112 g g−1, respectively, which are obviously higher than those reported for conventional LDHs and CLDHs. Possible mechanisms for the flower-like microsphere formation and the MO sorption are discussed. Our results demonstrate that, like traditional surfactant-based microemulsions, SFMEs as microreactors or templates can be used to synthesize nanomaterials. The hierarchical flower-like LDH microspheres and their calcined product have potential applications such as in the treatment of organic waste water.Hierarchical flower-like Mg2Al-Cl LDH microspheres were synthesized using a reverse surfactant-free microemulsion (SFME) route at a low temperature. The flower-like LDH and its calcined product exhibit superior sorption capacities for MO from aqueous solutions.Download high-res image (112KB)Download full-size image
Co-reporter:Jiling Liang, Lingxi Zhao, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 522(Volume 522) pp:
Publication Date(Web):5 June 2017
DOI:10.1016/j.colsurfa.2017.02.038
•Oil recovery from oily sludge via chemical cleaning was investigated.•Deoiling abilities of CTAB, Tween 60, NaOH, and SDBS reduce in turn.•Solid concentration (Cs) effect was observed in the chemical cleaning tests.•A Cs-dependent function of partition coefficient can describe the test data.•Effects of chemicals and temperature on the Cs-effect were examined.Oil recovery from oily sludge generated from the petroleum industry was investigated using a chemical cleaning method. Four chemicals including three surfactants, cationic cetyltrimethylammonium bromide (CTAB), nonionic Tween 60, and anionic sodium dodecylbenzenesulfonate (SDBS), and an alkali, NaOH, were used for the deoiling of oily sludge. Special emphasis was placed on the effect of sludge (solid) concentration (Cs) on the deoiling efficiency (Ro) and oil distribution coefficient (KD). The results showed that the deoiling abilities of CTAB, Tween 60, NaOH, and SDBS reduced in turn. A “solid effect” (Cs-effect) was clearly observed in the deoiling equilibrium, i.e., the KD increased with increasing Cs. The SCA-KD function, derived from the surface component activity (SCA) model we developed recently, can describe the Cs-effect observed. The values of two model parameters, intrinsic distribution coefficient (KD0) and Cs-effect constant (γ), were obtained for the chemical-sludge systems at various temperatures (T). Interestingly, we found that the Cs-effect strength (or γ value) was independent of the chemicals used in our tests, while increased with increasing T. Furthermore, the KD of NaOH increased with increasing T, which was confirmed to arise from the Cs-effect. Possible reasons for these results were discussed. This work provides a better insight into the deoiling behavior from oily sludge and confirms that the SCA model is a mathematical tool for analyzing deoiling data with the Cs-effect.Oil recovery from oily sludge via chemical cleaning was investigated and the solid concentration (Cs) effect was observed. A Cs-dependent function of partition coefficient can accurately describe the experimental data.Download high-res image (100KB)Download full-size image
Co-reporter:Huifang Xu;Na Du;Yawen Song;Shue Song;Wanguo Hou
Soft Matter (2005-Present) 2017 vol. 13(Issue 11) pp:2246-2252
Publication Date(Web):2017/03/15
DOI:10.1039/C6SM02665F
We report the spontaneous formation of vesicles from 2-ketooctanoic acid (KOCOOH), a single-tailed weakly acidic surfactant, in water. The vesicles were characterized using negative-staining, cryogenic transmission electron microscopy, conductivity, and atomic force microscopy. The pH effect on the vesicle formation and the stability of the vesicular structures were determined. The vesicles form at a very low concentration (ca. 1.4 mM) and within a wide pH range (ca. 2–10). Uni- and multilamellar vesicle structures are observed, which coexist in the KOCOOH solution. The hydrogen bonding between KOCOOH molecules probably plays an important role in the formation of the vesicles. Importantly, the vesicles exhibit remarkable stability upon long-term storage, and in artificial seawater. KOCOOH vesicles are a good alternative model system for protocell-like vesicles, as they are easily formed under plausible prebiotic conditions. In addition, they may have the same potential applications, such as in medicine, chemical engineering, and biotechnology, as conventional vesicles. To the best of our knowledge, this is the first report on the vesicles of single-tailed keto-acid amphiphiles.
Co-reporter:Huifang Xu;Na Du;Yawen Song;Shue Song;Wanguo Hou
Soft Matter (2005-Present) 2017 vol. 13(Issue 19) pp:3514-3520
Publication Date(Web):2017/05/17
DOI:10.1039/C7SM00458C
In the current work, the microviscosity, encapsulation, and permeability of 2-ketooctanoic acid (KOCOOH) vesicle membranes were investigated by steady-state and time-resolved fluorescence techniques, using 1,6-diphenyl-1,3,5-hexatriene (DPH), riboflavin, and calcein as fluorescence probes. Our results show that the microviscosity of KOCOOH membranes is similar to that of common bilayer aggregates, the KOCOOH vesicles have the ability to encapsulate hydrophilic guests, and the KOCOOH membranes are permeable to ions. The permeation of OH− across KOCOOH membranes can be well described using a first-order kinetic model. The KOCOOH vesicles may be a good alternative protocell model that possesses some functional properties necessary for early cell membranes. To the best of our knowledge, this is the first report on the characteristics of vesicle membranes of single-tailed keto-acid amphiphiles.
Co-reporter:Jie Xu;Huanhuan Deng;Yunlei Fu;Yuquan Chen;Jing Zhang;Wanguo Hou
Soft Matter (2005-Present) 2017 vol. 13(Issue 10) pp:2067-2074
Publication Date(Web):2017/03/08
DOI:10.1039/C7SM00155J
Generally, surfactants (or amphiphiles) are believed to be necessary components of microemulsions. However, it has been demonstrated that, in the absence of traditional surfactants, microemulsions can also form from a ternary system of two immiscible fluids (i.e., oil and water phases) and an amphi-solvent, but the current understanding of such surfactant-free microemulsions (SFMEs) is very limited. Herein, we report an SFME consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), the protic IL propylamine nitrate (PAN), and water, in which bmimPF6 and PAN are used as the oil phase and the amphi-solvent, respectively. The microstructures and structural transitions of the SFME were investigated using cyclic voltammetry, fluorescence spectroscopy, and ultraviolet-visible spectroscopy. The SFME exhibited water-in-bmimPF6 (W/IL), bicontinuous (BC), and bmimPF6-in-water (IL/W) microstructures, depending on the composition of the ternary system, similar to the case of traditional surfactant-based microemulsions (SBMEs). The three kinds of microstructures were confirmed by cryogenic transmission electron microscopy (cryo-TEM) observations. To the best of our knowledge, this is the first report on SFMEs composed of two ILs as components, especially where one is used as the amphi-solvent.
Co-reporter:Yaping Zhang, Xiaowen Wu, Haiping Li, Na Du, Shue Song, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 529(Volume 529) pp:
Publication Date(Web):20 September 2017
DOI:10.1016/j.colsurfa.2017.06.063
•Drug-intercalated LDH nanohybrids were synthesized via a coassembly route.•The drug-LDH nanohybrids were modified with liposome (LS) coating.•The (drug-LDH)@LSs showed excellent water dispersity.•The (drug-LDH)@LSs exhibited enhanced drug sustained-release performance.•The (drug-LDH)@LSs have great potential in drug delivery.Herein, we report a nanocomposite of betamethasone sodium phosphate (BMP), a glucocorticoid drug, intercalated layered double hydroxide (LDH) nanohybrids encapsulated in liposomes, denoted as BLN@LSs. The BMP-LDH nanohybrids (BLNs) were firstsynthesized via a coassembly route between BMP anions and LDH single-layer nanosheets (SLNSs), and then coated with liposomes consisting of lecithin and cholesterol. The re-dispersity, stability, and drug release behavior of the so-obtained nanocomposites were investigated. Compared with BLNs, the BLN@LSs exhibit excellent water re-dispersity and stability as well as enhanced drug sustained-release performance. The drug release processes can be described using the pseudo-second-order kinetic model, and intraparticle diffusion is the release rate-limiting step. Our work demonstrates that liposome-coating for drug-LDH nanohybrids is an effective strategy to enhance their water dispersity and sustained-release performances, and that (drug-LDH)@LS nanocomposites are a potential drug delivery system.Betamethasone sodium phosphate-intercalated layered double hydroxide nanohybrids were synthesized via a coassembly route and then coated with liposomes. The resultant nanocomposites exhibited excellent water dispersity and enhanced drug sustained-release performance.Download high-res image (119KB)Download full-size image
Co-reporter:Yaping Zhang, Haiping Li, Na Du, Shue Song, Wanguo Hou
Applied Clay Science 2017 Volume 143(Volume 143) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.clay.2017.04.001
•A hierarchical nanocomposite of (BDP-LDH)@LS was constructed.•BDP intercalated LDH nanohybrids were synthesized via a coassembly route.•The BDP-LDH nanohybrids were modified with liposome (LS) coating.•The (BDP-LDH)@LS shows excellent water dispersity and stability.•The (BDP-LDH)@LS exhibits enhanced drug sustained-release performance.A hierarchical nanocomposite of betamethasone dipropionate (BDP), a nonionic and lipophilic glucocorticoid drug, intercalated layered double hydroxide (LDH) encapsulated in liposome was constructed by combining host-gest chemistry with a core-shell strategy, to develop a LDH-based drug delivery system with remarkable water dispersity and good sustained-release performance. BDP molecules were first incorporated into sodium cholate (Ch) micelles, and the negatively charged BDP-loaded micelles were then coassembled with positively charged LDH single-layer nanosheets, forming a BDP/Ch intercalated LDH (BDP-Ch-LDH) gest-host nanohybrid. The BDP-Ch-LDH was further coated with liposome (LS) consisting of lecithin and cholesterol, gaining a core-shell nanocomposite, denoted as (BDP-Ch-LDH)@LS. The BDP-Ch-LDH and (BDP-Ch-LDH)@LS were characterized using small angle X-ray scanning, Fourier-transform infrared, transmission electron microscopy, and elemental analyses. Their water dispersity and stability as well as in vitro drug release behavior were investigated. The particle size and sedimentation rate of freeze-dried (BDP-Ch-LDH)@LS redispersed in water (~ 190 nm and 0.035 mm/h, respectively) are obviously lower than those of BDP-Ch-LDH (~ 761 nm and 1.028 mm/h, respectively). The maximum percentage releases of the (BDP-Ch-LDH)@LS in pH 7.4 and 4.8 PBSs (~ 60% and 80%, respectively) are also lower than those of the BDP-Ch-LDH (both ~ 90%) under the studied conditions. These results demonstrated that the (BDP-Ch-LDH)@LS has remarkable water dispersity and stability as well as enhanced drug sustained-release performance in comparison with BDP-Ch-LDH. The liposome-coating modification is an effective strategy for improving the practical performance of LDH-based drug delivery system.A hierarchical nanocomposite of betamethasone dipropionate/cholate intercalated LDH coated by liposome was constructed, using a coassembly route followed by a liposome-coating modification. The obtained nanocomposites exhibited excellent water dispersity and enhanced drug sustained-release performance.Download high-res image (96KB)Download full-size image
Co-reporter:Wanguo Hou, Jie Xu
Current Opinion in Colloid & Interface Science 2016 Volume 25() pp:67-74
Publication Date(Web):October 2016
DOI:10.1016/j.cocis.2016.06.013
•Microemulsions can form in a ternary system of oil, water, and an “amphi-solvent”.•Microemulsions without surfactants are called surfactant-free microemulsions (SFMEs).•SFMEs have similar structures and properties to surfactant-based microemulsions.•SFMEs are expected to have extensive potential applications.•This review focuses on recent advances in SFMEs.Surfactants (or amphiphiles) are generally believed to be a necessary component of microemulsions. However, research has found that in the absence of traditional surfactants, microemulsions can also form in a ternary system of two immiscible fluids and an “amphi-solvent”. Such microemulsions are called “surfactant-free microemulsions” (SFMEs). The so-called amphi-solvent is a solvent that is completely or at least partially miscible with each of the two immiscible fluids. The structures and properties of SFMEs are similar to those of traditional surfactant-based microemulsions (SBMEs) to some extent. This review focuses on recent advances in SFMEs, including their phase behavior, structures, properties and potential applications.Microemulsions can form from a mixture of two immiscible fluids and an “amphi-solvent” in the absence of traditional surfactants. The structures and properties of these surfactant-free microemulsions are similar to those of traditional surfactant-based microemulsions to some extent.
Co-reporter:Tingxia Hu, Haiping Li, Renjie Zhang, Na Du and Wanguo Hou
RSC Advances 2016 vol. 6(Issue 38) pp:31744-31750
Publication Date(Web):24 Mar 2016
DOI:10.1039/C6RA03268K
Bismuth tungstate (Bi2WO6) nanosheets with dominant exposed (010) facets and various thicknesses (H) and lateral sizes were hydrothermally synthesized via pH adjustment of precursor suspensions. As the pH increases from <1 to 8, the resultant nanosheets exhibit improved crystallinity and photoabsorption, decreased specific surface area, increased H, and decreased photoactivity in the degradation of rhodamine B (RhB), methylene blue (MB), and Eosin Y (EY) under visible light irradiation. The photoactivity of the Bi2WO6 sample obtained at pH < 1 is about 6, 100, and 25 times of that at pH 8 for RhB, MB, and EY degradation, respectively. The photoactivity enhancement is ascribed to reduction of the H. The photocatalytic efficiencies are inversely proportional to the reduction of H2 when the nanosheets can be penetrated by incident light. This work reveals the structure–performance relationship of Bi2WO6 nanosheets and provides significant guidance for preparation of high efficient two-dimensional photocatalysts.
Co-reporter:Tianrong Zhan, Yang Song, Xianjun Li, Wanguo Hou
Materials Science and Engineering: C 2016 Volume 64() pp:354-361
Publication Date(Web):1 July 2016
DOI:10.1016/j.msec.2016.03.093
•Ionic liquids functionalized layered double hydroxide (ILs-LDH) nanohybrid was synthesized by coprecipitation technique.•ILs-LDH significantly enhanced the oxidation peak response and decreased the anodic overpotential of bisphenol A.•Differential pulse voltammetry determination of bisphenol A presented a broad linear range with low detection limit.•The proposed sensor exhibited satisfactory reproducibility, stability and selectivity.The plate-like Zn-Al layered double hydroxide modified with 1-aminopropyl-3-methylimidzaolium tetrafluoroborate (named as ILs-LDH) was synthesized by coprecipitation method. Several techniques confirmed the layered structure of ILs-LDH with a disk-like morphology. A novel electrochemical sensor based on ILs-LDH modified glass carbon electrode (GCE) was developed for bisphenol A (BPA) determination. Experimental factors including modified content, pH, scan rate, accumulation time and potential had been carefully optimized. ILs-LDH/GCE performed the excellent electro-oxidation ability toward BPA with the more negative oxidation overpotential and larger peak current than bare GCE or LDH/GCE. Differential pulse voltammetry determination of BPA afforded a wider linear range from 0.02 to 3 μM with the detection limit of 4.6 nM (S/N = 3). The fabricated sensor demonstrated an acceptable reproducibility, good stability and high sensitivity. The proposed method was successfully used to detect BPA in real water samples with satisfactory recovery ranging from 94.9% to 102.0%.
Co-reporter:Yaping Zhang, Haiping Li, Na Du, Renjie Zhang, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 501() pp:49-54
Publication Date(Web):20 July 2016
DOI:10.1016/j.colsurfa.2016.04.046
•Layered double hydroxide single-layer nanosheets (SLNSs) were synthesized.•The synthesis includes three steps: coprecipitation, washing, and redispersion.•No organic modifiers or organic solvents were used in the synthesis.•The SLNSs in dispersion remains stable for at least 2 d at room temperature.•The SLNSs can be directly used as building blocks for functional materials.Inorganic layered double hydroxide (LDH) single-layer nanosheets (SLNSs) are traditionally synthesized with the assistance of organic chemicals or in organic solvents, resulting in organic-coated SLNSs or organic dispersions of SLNSs, which may limit their potential applications. Herein, we report, for the first time, a simple aqueous synthetic route to naked (uncoated) LDH SLNSs; this route, which is termed the PWD route for simplicity, includes three steps: aqueous coprecipitation, water-washing, and redispersion in water. The obtained LDH SLNSs were characterized using TEM, AFM, XRD, and dynamic light scattering techniques, and the stability of the LDH SLNS dispersions was determined. Moreover, the co-assemblies of the LDH SLNSs with negatively charged guests, sodium cholate and graphene oxide, were investigated. Results showed that the SLNSs can remain stable (i.e., without layer-by-layer stacking) for a period of time, depending on temperature, and can be directly used as building blocks for functional materials. This new route has many advantages including its simple operation, environmental friendliness, low cost, and ease of large-scale application.
Co-reporter:Tianrong Zhan, Xinjun Wang, Xianjun Li, Yang Song, Wanguo Hou
Sensors and Actuators B: Chemical 2016 Volume 228() pp:101-108
Publication Date(Web):2 June 2016
DOI:10.1016/j.snb.2015.12.095
A sandwich-like nanocomposite of exfoliated Co2Al layered double hydroxide (ELDH) and graphene (GR) was synthesized by chemically reducing in situ the assembly of ELDH and graphene oxide (GO) nanosheets. The morphology and structure of the product were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). Then the ELDH-GR nanocomposite and chitosan (CTS) were employed for immobilization of hemoglobin (Hb) on a carbon ionic liquid electrode (CILE) to fabricate a trichloroacetic acid (TCA) biosensor. The UV-Vis, FTIR and fluorescence spectra showed that Hb kept its native structure and retained stable bioactivity in the composite material. Cyclic voltammetry (CV) displayed a pair of well-defined redox peaks with the formal peak potential (E0′) at −0.256 V (vs. SCE), in pH 4.0 Britton–Robinson solution at the scan rate of 0.1 V/s, implying the direct electron transfer of Hb–FeIII/FeII. The electron transfer coefficient (α) and the apparent heterogeneous electron transfer rate constant (ks) were calculated to be 0.492 and 1.202 s−1, respectively. The Hb-modified electrode presented excellent electro-reduction activity toward TCA in the concentration range from 5 to 360 mmol/L with the detection limit of 1.506 mmol/L (3σ) by CV. For square wave voltammetry (SWV), the concentration range and the detection limit were from 2.5 to 360 mmol/L and 0.82 mmol/L, respectively. Therefore, the ELDH-GR composite has a promising potential for construction of biosensors.
Co-reporter:Na Du, Ruiying Song, Hongshu Zhang, Jichao Sun, Shiling Yuan, Renjie Zhang, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 509() pp:195-202
Publication Date(Web):20 November 2016
DOI:10.1016/j.colsurfa.2016.09.006
•SDS vesicles formed in its micellar solution without other additives with the mediation of a rough glass surface (RGS).•SDS vesicles showed highly stable characters due to “interdigitated structure” of vesicle bilayers.Under the mediation of a rough glass surface (RGS), formation of vesicles was realized from a micellar solution of only a simple anionic single-tailed surfactant (STS), sodium dodecylsulfate (SDS), to form a mixed solution of micelles and vesicles. Interestingly, the SDS vesicles formed in the solution displayed good stability upon long-term storage, exposure to high temperature, freeze–thawing, and high salinity after the RGS removal. Adsorption and water contact angle measurements demonstrated that SDS could adsorb on the RGS to form bilayers in which the molecular packing parameter of SDS was in the range of 1/2–1. The bilayer adsorption and the roughness of the solid surface played an important role in vesicle formation. AFM observations suggested that the alkyl tails of SDS in the vesicular bilayer membranes were partially interdigitated, and molecular dynamics simulations revealed that the partially interdigitated bilayer structure is crucial for the formation and stability of the SDS vesicles. This work contributes to the understanding of the nature of vesicle systems.
Co-reporter:Song Lu;Haiping Li;Fengrong Zhang;Na Du;Wanguo Hou
Colloid and Polymer Science 2016 Volume 294( Issue 8) pp:1369-1379
Publication Date(Web):2016 August
DOI:10.1007/s00396-016-3893-8
Carboxymethyl chitosan (CMCS)-conjugated magnetite (Fe3O4) nanoparticles (MNPs), which are denoted as CMCS-MNPs, were synthesized by covalently binding CMCS onto the surface of the MNPs via carbodiimide activation in a paraffin-acetic acid medium. The CMCS-MNPs exhibited a high level of CMCS binding (∼24.7 wt.%) and a spherical morphology with a mean diameter of 15 nm. In particular, they showed good water dispersity and a strong magnetic response. The sorption of Pb(II) on the CMCS-MNPs in aqueous solutions at different sorbent dosages (Cs), pH, electrolyte (NaNO3) concentrations (CNaNO3), and temperatures (T) was investigated. The CMCS-MNPs showed high sorption capacity for Pb(II). The equilibrium amount increased with increasing pH but decreased with increasing CNaNO3 or T. In addition, a significant Cs-effect was observed in the sorption equilibria. Two Cs-dependent models, the Langmuir-SCA and Freundlich-SCA isotherms that were derived from a surface component activity (SCA) model, could describe the Cs-effect observed. The changes in pH, CNaNO3, and T have no obvious influence on the Cs-effect. In addition, the changes in the thermodynamic parameters, ∆G°, ∆H°, and ∆S°, for sorption were estimated, showing that the sorption process is spontaneous and exothermic.
Co-reporter:Fengrong Zhang, Yawen Song, Shue Song, Renjie Zhang, and Wanguo Hou
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 13) pp:7251
Publication Date(Web):March 20, 2015
DOI:10.1021/acsami.5b00433
Magnetic composites consisting of magnetite (Fe3O4), graphene oxide (GO), and Mg3Al–OH layered double hydroxide (LDH), denoted as MGL composites, with varying GO contents (RGO) were synthesized by a mechano-hydrothermal (MHT) route using Fe3O4, Mg(OH)2, and Al(OH)3 as the inorganic starting materials. The application of the synthesized MGLs for removing the heavy-metal Pb(II) and the hydrophobic organic pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions was investigated. Chemical bonding among the GO, Fe3O4, and LDH components was observed in the MGLs. The MGL composites showed good water-dispersity, strong magnetic response, and high sorption capacities and removal efficiencies for both Pb(II) and 2,4-D pollutants. The sorption capacities of the MGL for the pollutants significantly increased with an increase in RGO. Increasing pH could increase the removal efficiency for Pb(II) but decrease that for 2,4-D. The MGLs showed more affinity for Pb(II) than for 2,4-D in the competitive sorption. In addition, the MGLs could remain almost constant removal efficiency for the pollutants after reuse over six cycles, indicating their potential use as sorbents in wastewater treatment. Furthermore, a Cs effect was observed in the sorption equilibriums, which could be described using the Langmuir-SCA and Freundlich-SCA isotherms. The removal mechanisms of the MGL for Pb(II) and 2,4-D were discussed. The MHT method provided a simple and environmentally friendly route for synthesizing GO–LDH composite materials.Keywords: graphene oxide; layered double hydroxide; magnetic composite; mechano-hydrothermal method; sorbent effect; sorption; surface component activity
Co-reporter:Fengrong Zhang, Na Du, Shue Song, Wanguo Hou
Materials Chemistry and Physics 2015 Volume 152() pp:95-103
Publication Date(Web):15 February 2015
DOI:10.1016/j.matchemphys.2014.12.019
•SDS intercalated LDHs were synthesized via a mechano-hydrothermal route.•Intercalation amount of SDS into LDHs could be easily quantitatively controlled.•The nanohybrids had a higher sorption capacity for 2,4-D than LDHs.•An obvious Cs-effect existed in the sorption of 2,4-D on the nanohybrids.•The Cs-effect can be described with Langmuir-SCA and Freundlich-SCA models.Sodium dodecyl sulfate (SDS) intercalated Mg3Al layered double hydroxide (LDH), denoted as DS-LDH, nanohybrids were synthesized via mechano-hydrothermal (MHT) route. The intercalation amount (Ain) of dodecyl sulfate (DS) anions into LDHs could be easily quantitatively controlled by the molar ratio of SDS to Al(OH)3 in the starting materials. The removal efficiency (ER) of the DS-LDHs for 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions was determined. With increasing Ain, the ER increased. An obvious sorbent concentration effect (Cs-effect) was observed: the saturation sorption capacity of 2,4-D on the DS-LDHs decreased as Cs increased. The sorption isotherms of 2,4-D on the DS-LDHs for any given Cs values can be described with the Langmuir and Freundlich isotherms. The Cs-effect can be described with the surface component activity (SCA) model, namely, Langmuir-SCA and Freundlich-SCA isotherms. The nanohybrids are promising sorbents for treating 2,4-D-containing wastewater, and the MHT method can be used to synthesize DS-LDH sorbents.Sodium dodecyl sulfate (SDS) intercalated Mg3Al layered double hydroxide (LDH) nanohybrids were synthesized via a mechano-hydrothermal route. The intercalation amount of SDS into LDHs could be easily quantitatively controlled. In addition, a Cs-effect existed in the sorption of 2,4-D on DS-LDHs, which can be adequately described with both the Langmuir-SCA and Freundlich-SCA models.
Co-reporter:Fengrong Zhang;Na Du;Haiping Li;Shue Song;Wanguo Hou
Colloid and Polymer Science 2015 Volume 293( Issue 7) pp:1961-1969
Publication Date(Web):2015 July
DOI:10.1007/s00396-015-3592-x
In this study, the sorption of hexavalent chromium, Cr(VI), on a Mg6AlFe-layered double hydroxide (LDH) and its calcined product (layered double oxide, LDO) in aqueous solutions was investigated using a batch technique at various sorbent dosages (Cs). A significant sorbent effect (Cs-effect) was observed in the sorption systems; the sorption isotherms declined as Cs increased. The Langmuir and Freundlich isotherms can describe the sorption equilibriums at each given Cs well but cannot describe the Cs-effect observed. These Cs-effect data can be described by the surface component activity (SCA) model, namely, the Langmuir-SCA and Freundlich-SCA isotherms. The Cs-effect in the LDO system is stronger than that in the LDH system, which can be attributed to the higher specific surface area of the LDO than that of the LDH. Furthermore, the characteristic saturation sorption capacity of the LDO for Cr(VI), which was obtained from the SCA model, is higher than that of the LDH, indicating that LDOs are more effective sorbents than LDHs are for heavy metal removal. In addition, the influences of pH and electrolyte (NaNO3) concentration (CNaNO3) on the Cs-effect were examined; no significant effects were observed upon changing either the solution pH (5–9) or CNaNO3 (0.001–0.100 mol/L). This work improves our understanding of the Cs-effect phenomenon and confirms the applicability of the SCA model in describing sorption equilibriums with the Cs-effect.
Co-reporter:Na Du, Ruiying Song, Haiping Li, Shue Song, Renjie Zhang, and Wanguo Hou
Langmuir 2015 Volume 31(Issue 46) pp:12579-12586
Publication Date(Web):November 2, 2015
DOI:10.1021/acs.langmuir.5b03477
We report a novel model system of precursor cellular membranes, self-assembled from micellar solution of a common anionic single-tailed amphiphile (STA), including sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS). The self-assembly process was mediated with solid surfaces of Mg2Al-CO3 hydrotalcite-like compound (HTlc), an anionic clay, in the absence of cosurfactants or any additives. The resultant STA vesicles were characterized using negative–staining and cryogenic transmission electron microscopies, as well as dynamic light scattering and steady state fluorescence techniques. Interestingly, the obtained STA vesicles displayed good stability even after the removal of the anionic clay surface (ACS), and a self-reproduction phenomenon was observed for the “preformed” STA vesicles when mixing with corresponding STA micellar solutions. More importantly, the micelle-to-vesicle transition for SDS could be still arisen in high-salinity artificial seawater under the ACS mediation. Instead of conventional fatty acid scenario, our finding provides another novel possible model for protocell-like vesicles, which are easily formed under the plausible prebiotic conditions.
Co-reporter:Ruiying Song, Na Du, Xiaoyu Zhu, Haiping Li, Shue Song, and Wanguo Hou
The Journal of Physical Chemistry B 2015 Volume 119(Issue 9) pp:3762-3767
Publication Date(Web):February 16, 2015
DOI:10.1021/jp509795v
In this paper, we report a micelle-to-vesicle transition in aqueous solution of the anionic single-tailed surfactant (STS) sodium dodecylbenzenesulfonate (SDBS), with the mediation of a rough glass surface (RGS) in the absence of cosurfactants or additives. This transition produced a mixed solution of vesicles and micelles. Interestingly, the obtained SDBS vesicles in the solution displayed good stability during a long-term storage (at least 6 months at room temperature), exposure to high temperature (80 °C for 2 h), and freeze–thawing (−20 or −196 °C for 2 h to approximately 25 °C) after the RGS was removed. Our results confirmed that SDBS could adsorb on the RGS to form bilayers, in which the molecular packing parameter of SDBS was in the range of 1/2–1. The bilayer adsorption and the roughness of the solid surface played an important role in the vesicle formation. In addition, we propose a possible mechanism for the RGS-mediated transition of micelle-to-vesicle in SDBS solutions: SDBS micelles and molecules adsorb on the RGS to form curved bilayers; the curved bilayers detach from the RGS, and then close to form vesicles.
Co-reporter:Jiling Liang, Na Du, Shue Song, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 466() pp:197-202
Publication Date(Web):5 February 2015
DOI:10.1016/j.colsurfa.2014.11.050
•Oleic acid-coated magnetite nanoparticles are a potential magnetic demulsifier.•The demulsifier can magnetically break diluted crude oil-in-water nanoemulsions.•The demulsification efficiency of the demulsifier is influenced by its wettability.•Multistep demulsification shows a higher efficiency than the single-step operation.•The magnetic demulsifier exhibits a good reusability.Most produced crude oil and oily wastewater from oilfields typically exist in the form of emulsions; this makes their demulsification a very challenging process. Chemical demulsifiers are commonly employed to enhance demulsification efficiency (ED). However, there is still an urgent need to develop more efficient techniques and demulsifiers to meet eco-friendly and economically competitive requirements. In this study, magnetic demulsification of single-layer oleic acid-coated magnetite (Fe3O4@OA) nanoparticles as a demulsifier for cyclohexane-diluted crude oil-in-water nanoemulsions (denoted as CO-NEs) was investigated under an external magnetic field. The effects of the dosage and wettability of the demulsifier, the pH of the CO-NEs, and the demulsification operation process on the ED were examined. The ED increased with increasing Fe3O4@OA dosage and a high ED of ∼97% was reached, which demonstrates the potential of Fe3O4@OA nanoparticles as a magnetic demulsifier for crude oil-containing emulsions from oilfields. The ED is related to the wettability (or water contact angle) of the magnetic nanoparticles, and a maximum ED was observed at a water contact angle of ∼90°. The ED was almost unchanged in the pH range of 4.0–7.5, while it gradually decreased as the pH rose from 8.0 to 11.0. Multistep demulsification exhibited a higher ED than the single-step operation when the same amounts of demulsifier were used. The Fe3O4@OA nanoparticles exhibited good recyclability; no significant change in the ED of the recycled Fe3O4@OA after demulsification was observed over five cycles. This work improves the understanding of demulsification behaviors of magnetic demulsifiers.Single-layer oleic acid-coated magnetite (Fe3O4@OA) nanoparticles show potential for magnetically demulsifying diluted crude oil-in-water nanoemulsions from oilfields. The demulsification efficiency was influenced by the dosage and wettability of the nanoparticles, the pH and the demulsification operation process.
Co-reporter:Haiping Li, Jingyi Liu, Xuefeng Liang, Wanguo Hou and Xutang Tao
Journal of Materials Chemistry A 2014 vol. 2(Issue 23) pp:8926-8932
Publication Date(Web):08 Apr 2014
DOI:10.1039/C4TA00236A
BiOBr lamellas were synthesized at different reaction pH values via a hydrothermal process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and N2 sorption measurements were used to characterize the BiOBr samples. BiOBr samples have the same lamella structures and band gaps but different lamella sizes and thicknesses. Adjusting the pH of the reaction system tunes the BiOBr lamella thickness from 42 to 21 nm. The photodegradation efficiencies of the BiOBr lamellas for rhodamine B (RhB) and methylene blue (MB) in aqueous solution were examined. The degradation efficiency for RhB is much higher than that for MB. The decrease in BiOBr lamella thickness significantly enhances the photocatalytic activity for dye degradation, despite the decrease in exposed photoactive (001) facet percentage. Decreasing the lamella thickness from 42 to 21 nm yields a more than fourfold enhancement in photodegradation efficiency of BiOBr samples for RhB. The most important factor influencing the photocatalytic activity of the BiOBr samples is their lamella thickness, rather than the exposed (001) facet percentage. Thus, even for flaky semiconductors with high exposed photoactive facet contents, the influence of lamella thickness on photocatalytic activity should be preferentially considered.
Co-reporter:Na Du, Ruiying Song, Xiaoyu Zhu, Wanguo Hou, Haiping Li and Renjie Zhang
Chemical Communications 2014 vol. 50(Issue 73) pp:10573-10576
Publication Date(Web):09 May 2014
DOI:10.1039/C4CC02047B
Novel vesicles formed spontaneously from the micelle solution of DTAB, a single-tailed surfactant (STS), mediated by a rough glass surface (RGS) without any additives. The obtained STS vesicles displayed good stability upon long-term storage, exposure to high temperatures, and freeze-thawing after the removal of RGS.
Co-reporter:Haiping Li, Quanhua Deng, Jingyi Liu, Wanguo Hou, Na Du, Renjie Zhang and Xutang Tao
Catalysis Science & Technology 2014 vol. 4(Issue 4) pp:1028-1037
Publication Date(Web):15 Jan 2014
DOI:10.1039/C3CY00940H
Bi2MoO6/Zn–Al layered double hydroxide (LDH) hierarchical heterostructures assembled from Bi2MoO6 hierarchical hollow spheres and Zn–Al LDH nanosheets were synthesized by a low-temperature hydrothermal method. X-ray diffraction, Fourier transform-infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS) confirmed the formation of the Bi2MoO6/Zn–Al LDH composites. Morphologies were characterized by scanning electron microscopy and transmission electron microscopy (TEM). XPS and high resolution TEM indicated the formation of a Bi2MoO6/Zn–Al LDH heterojunction. Increasing the LDH content from 0 to 27.0 wt.% caused the Brunauer–Emmett–Teller (BET) specific surface area of the composites to gradually increase. The photocatalytic degradation activity for Rhodamine B (RhB) under visible light irradiation exhibited a large enhancement, followed by a decrease, with increasing LDH content. The Bi2MoO6/Zn–Al LDH heterostructure composite with LDH content of 5.5 wt.% showed the highest photocatalytic activity and degraded 99% of RhB in 80 min, while Bi2MoO6 degraded less than 50%. The average photocatalytic efficiency is enhanced by more than 100%. The enhanced photocatalytic activity of the Bi2MoO6/Zn–Al LDH heterostructure photocatalyst was mainly attributed to the efficient separation of photoinduced electrons and holes. Superoxide radicals and holes were the major active species. The Bi2MoO6/Zn–Al LDH heterostructure photocatalyst exhibited excellent stability and reusability. A detailed mechanism for its enhanced photocatalytic activity was discussed in this study. This work provides an effective way to fabricate a series of Bi-based and LDH-containing heterostructure photocatalysts.
Co-reporter:Tianrong Zhan, Qi Yang, Yumei Zhang, Xinjun Wang, Jie Xu, Wanguo Hou
Journal of Colloid and Interface Science 2014 Volume 433() pp:49-57
Publication Date(Web):1 November 2014
DOI:10.1016/j.jcis.2014.07.012
•The introduction of HFIL enhanced the maximum Hb loading in LDH for both adsorption and coprecipitation methods.•Nanocomposite HFIL–LDH could keep the secondary structure and redox-active heme groups of Hb intact.•The coprecipitation bioelectrode displayed the better performance than that of the corresponding adsorption one.•The presence of HFIL could distinctly promote the electron transport.•Rapid electron transfer between Hb and GCE (for HFIL–LDH–Hbcop/GCE) due to HFIL–LDH nano-interface.Hemoglobin (Hb) was immobilized in Zn2Al-Layered Double Hydroxides (LDH) modified with Hydroxyl Functionalized Ionic Liquid (HFIL) through adsorption and coprecipitation method, respectively. Adsorption experiments showed that the presence of HFIL could enhance the maximum protein loading. However, the Hb loading through coprecipitation technique was far higher than that for adsorption. The role of HFIL on the interaction between Hb and LDH was investigated by XRD, FTIR, UV–vis and fluorescence spectroscopies. Although the quaternary structure of Hb entrapped in HFIL–LDH through coprecipitation technique (denoted as HFIL–LDH–Hbcop) might be altered slightly more than that in LDH (LDH–Hbcop), its secondary structure and redox-active heme groups kept intact. Morphologies of LDH–Hbcop and HFIL–LDH–Hbcop biohybrids were analyzed through SEM and TEM images. The direct electrochemistry of the immobilized Hb indicated that the coprecipitation bioelectrode performed better than that of the corresponding adsorption one. Regardless of adsorption and coprecipitation, the introduction of HFIL could distinctly promote the electron transport. Among all bioelectrodes, HFIL–LDH–Hbcop/GCE displayed the best electrocatalytic activity for H2O2 determination with a larger electroactive Hb percentage (6.76%), higher sensitivity (40.63 A/M cm2) and lower detection limit (0.0054 μmol/L). So HFIL–LDH could effectively immobilize enzymes via coprecipitation technique, which had potential applications in the fabrication of electrochemical biosensors.Graphical abstract
Co-reporter:Jiling Liang, Haiping Li, Jingen Yan, and Wanguo Hou
Energy & Fuels 2014 Volume 28(Issue 9) pp:6172-6178
Publication Date(Web):August 12, 2014
DOI:10.1021/ef501169m
Oleic acid (OA)-coated magnetite (Fe3O4) nanoparticles, denoted Fe3O4@OA, were synthesized by co-precipitation in the presence of varying contents of OA. The Fe3O4@OA nanoparticles were characterized by X-ray diffraction, transmission and scanning electron microscopies, Fourier transform infrared spectroscopy, thermogravimetric–differential thermogravimetric analyses, and vibrating sample magnetometry. Increasing the OA content during preparation resulted in an increase of the OA-coating amount (AO, in units of g of OA/g of Fe3O4) on the Fe3O4 surface, before reaching an equilibrium value. The resulting magnetic nanoparticles were nearly spherical with a size of ∼12–14 nm. OA molecules formed a single layer coating on the Fe3O4 surface. The AO and area occupied by a single OA molecule at saturation coating were estimated to be 0.11 g g–1 (1.22 mg m–2) and 0.37 nm2, respectively. The Fe3O4@OA nanoparticles were applied in the demulsification of a cyclohexane-in-water nanoemulsion, under an external magnetic field. The effects of AO, demulsifier dosage, pH, and electrolytes on the demulsification efficiency (ED) were investigated. The ED increased and then decreased with increasing AO, which was attributed to a change in wettability of the magnetic nanoparticles. A maximum ED of ∼98% was observed at a ∼90° contact angle between water and the magnetic nanoparticles. The ED was independent of pH and electrolyte (NaCl or CaCl2) concentration, under the studied conditions. The magnetic demulsifier exhibited excellent stability after reuse over 6 cycles. Fe3O4@OA nanoparticles are effective for oil–water multiphase separation and treating oily wastewater.
Co-reporter:Fengrong Zhang, Na Du, Haiping Li, Xuefeng Liang and Wanguo Hou
RSC Advances 2014 vol. 4(Issue 87) pp:46823-46830
Publication Date(Web):15 Sep 2014
DOI:10.1039/C4RA07553F
Mg–Al–Fe layered double hydroxides (LDHs) with a constant Mg2+/(Fe3+ + Al3+) molar ratio but varying Fe3+/(Al3+ + Fe3+) molar ratios (RFe) from 0–1 were synthesized by a mechanochemical method. Sorption of Cr(VI) on the LDHs in aqueous solutions was investigated by a batch technique. The sorption process obeyed pseudo-second-order kinetics, and the sorption equilibrium could be well described with the Freundlich isotherm. The saturated sorption amount increased with increasing RFe, indicating that the replacement of Al by Fe in LDHs is favorable for Cr(VI) sorption. The mechanisms of Cr(VI) sorption included the intercalation of Cr(VI) oxyanions into the LDH gallery, and the surface complexation between dichromate anions and hydroxyl groups of the LDHs. The driving forces of Cr(VI) sorption on LDHs included physical binding (or electrostatic attraction) and chemical binding. The physically sorbed amount of Cr(VI) on the LDHs was almost independent of RFe, while the chemically sorbed amount obviously increased with increasing RFe. That is, the increase of RFe causes the chemical activity of surface sorption sites of the LDHs to increase, resulting in their sorption capacity for Cr(VI) increasing. In addition, the sorption capacity of the LDHs synthesized by the mechanochemical method is comparable with those of LDHs synthesized by coprecipitation and hydrothermal methods. Thus, Mg–Fe LDHs are promising sorbents for treating Cr(VI)-containing wastewater, and the mechanochemical method can be used to synthesize LDH sorbents.
Co-reporter:Jingyi Liu, Haiping Li, Na Du, Shue Song and Wanguo Hou
RSC Advances 2014 vol. 4(Issue 59) pp:31393-31399
Publication Date(Web):08 Jul 2014
DOI:10.1039/C4RA04829F
BiOI hierarchical flower-like microspheres were hydrothermally prepared, using tetrabutylammonium iodide as an iodine source and template. Many BiOI hierarchical structures have been synthesized using KI, NaI, HI or ionic liquids as the iodine source, but the use of alkyl ammonium iodide as the iodine source was not reported in the literature. The so-obtained BiOI samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen sorption measurements, and ultraviolet-visible diffuse reflectance spectroscopy. The effects of hydrothermal temperature and time on the BiOI crystal structure and morphology were investigated. The BiOI microspheres were composed of BiOI nanosheets. The photocatalytic performance of the BiOI samples was determined from the degradation of Rhodamine B, under visible light irradiation. BiOI microspheres prepared at 160 °C over 30 h exhibited excellent photodegradation efficiency, which was more than five and seven times higher than those of BiOI nanoplates and N-doped TiO2, respectively. The high photocatalytic performance was attributed to the high specific surface area and low nanosheet thickness. A morphologic factor was proposed to represent the ratio of specific surface area to nanosheet thickness, and correlated to the photodegradation efficiency of the BiOI samples. The photocatalytic efficiency increased with increasing morphologic factor. The BiOI photocatalyst exhibited excellent stability and reusability, and has potential in environment remediation.
Co-reporter:Chunfang Li, Yanhai Qi, Qianru Li, Dongxiang Li, Wanguo Hou
Journal of Luminescence 2014 Volume 147() pp:273-277
Publication Date(Web):March 2014
DOI:10.1016/j.jlumin.2013.11.048
•Fluorescent 6-carboxyfluorescein/HTlc nanocomposites were synthesized.•Fluorescent dye molecules are primarily adsorbed on HTlc surface.•Nanocomposite luminescence is related with the cluster structure of fluorescent dyes.The nanocomposites of fluorescent dye/hydrotalcite-like compounds (HTlc) synthesized by intercalation and/or surface adsorption methods have exhibited specific photophysical and photochemical property. In this work, 6-carboxyfluorescein (6CF)/HTlc nanocomposites were synthesized by ammonia coprecipitation and reconstruction-induced surface adsorption methods, and they were characterized by powder X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Thermogravimetric differential thermal measurements (TG-DTA) and fluorescence spectra. The results demonstrate that the dye molecules are primarily adsorbed on HTlc surface. The fluorescence emission of 6CF/Mg–Al HTlc composites is related with 6CF dosage due to the self-quenching mechanism. The 6CF/Zn–Al HTlc nanocomposite reconstructed at high temperature have much strong luminescence than that reconstructed at room temperature and the 6CF/Mg–Al HTlc nanocomposites.
Co-reporter:Fengrong Zhang, Na Du, Haiping Li, Jianqiang Liu, Wanguo Hou
Solid State Sciences 2014 Volume 32() pp:41-47
Publication Date(Web):June 2014
DOI:10.1016/j.solidstatesciences.2014.03.012
•Hydrothermal treatment was combined with a pre-milling process.•The synthesis route could be completed at low temperature.•Resulting LDHs were well-crystallized and dispersed.•Resulting LDHs have high removal efficiency for heavy metal pollutants.Mg–Al–Fe–NO3 layered double hydroxides (LDHs) with a constant Mg2+/(Al3+ + Fe3+) molar ratio but varying Al3+/Fe3+ molar ratios were successfully synthesized by a mechano-hydrothermal (MHT) method from Mg(OH)2, Al(OH)3 and Fe(NO3)3·9H2O or Mg(NO3)2·6H2O as starting materials. The resulting LDHs (MHT-LDHs) were characterized by XRD, TEM, SEM, FT-IR, and zeta potential, size distribution and specific surface area analyses. It was found that pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The MHT route is advantageous in terms of low reaction temperature compared with the conventional hydrothermal method, and the target products are of high crystallinity and good dispersion compared with the conventional mechanochemical (MC) method. The MHT-LDHs had higher specific surface area and zeta potential, and lower hydrodynamic diameter than LDHs obtained by MC method (MC-LDHs). Furthermore, the removal of Cr(VI) from aqueous solutions using the LDHs was examined, showing that the MHT-LDHs are of higher removal efficiency than MC-LDHs for the heavy metal pollutant.High crystallized and well-dispersed Mg–Al–Fe–NO3 LDHs were synthesized via mechano-hydrothermal route. The LDHs show high removal efficiency for heavy metal pollutants from aqueous solutions.
Co-reporter:Chunfang Li;Zhupeng Zhang;Jinrong Wu;Dongxiang Li;Wanguo Hou
Polymer International 2014 Volume 63( Issue 10) pp:1875-1880
Publication Date(Web):
DOI:10.1002/pi.4725
Abstract
Dendritic amphiphiles as novel building blocks are very important for self-assembling in the supramolecular chemistry area. In this work, a carbosilane dendrimer with hexamethylene as the branching unit (G1) was first synthesized as a hydrophobic core and then linked with poly(ethylene glycol) (PEG) units as the periphery by a hydrosilylation reaction to prepare an amphiphilic dendrimer (G1-PEG) with a yield of 27%. The aggregation behavior of G1-PEG in water was studied with surface tension, dynamic light scattering and transmission electron microscopy methods. The surface tension data showed that the critical aggregation concentration of such dendrimers in water is approximately 0.75 g L−1. The results of dynamic light scattering and transmission electron microscopy indicated that the aggregate size of G1-PEG dendrimers in water is related to the concentration. Small micelles of about 10 nm were found at high concentration, large vesicles of about 100 nm were observed at low concentration, and a mixture of micelles and vesicles was found at middle concentrations. The encapsulation of G1-PEG to a fluorescence probe verified the existence of a hydrophobic microenvironment in the aggregates at high concentrations of the amphiphilic dendrimer. © 2014 Society of Chemical Industry
Co-reporter:Jiling Liang, Lingxi Zhao, Na Du, Haiping Li, Wanguo Hou
Separation and Purification Technology 2014 130() pp: 28-33
Publication Date(Web):
DOI:10.1016/j.seppur.2014.03.027
Co-reporter:Xiaoyu Zhu, Na Du, Ruiying Song, Wanguo Hou, Shue Song, and Renjie Zhang
Langmuir 2014 Volume 30(Issue 39) pp:11543-11551
Publication Date(Web):2017-2-22
DOI:10.1021/la502965q
We report novel vesicles composed of the zwitterionic surfactant lauryl sulfobetaine (LSB), which is a simple single-tailed surfactant (STS). The novel vesicles spontaneously formed from LSB micellar solutions with the mediation of a rough glass surface (RGS) in the absence of any cosurfactants or additives. Importantly, the obtained STS vesicles displayed good stability upon long-term storage, exposure to high temperature, and freeze–thawing after the RGS was removed. The pH of the LSB solution (4.0–9.0) and the presence of NaCl (1.0 × 10–5 and 1.0 × 10–4 mol/L) in the LSB solution had no obvious influence on the formation and stability of the vesicles. The adsorption configuration of LSB on the RGS was investigated via water contact angle measurements and atomic force microscope observations. The results showed that LSB adsorption bilayers could form on the RGS, and the bilayer adsorption of LSB on the RGS and the roughness of the solid surface played a key role in the vesicle formation. A possible mechanism for the RGS-mediated formation of LSB vesicles is proposed: LSB micelles and molecules adsorb on the RGS to form curved bilayers, and the curved bilayers are then detached from the RGS and close to form vesicles. To the best of our knowledge, this is the first report of LSB alone forming vesicles. This finding extends our understanding of the nature of vesicle systems.
Co-reporter:Jikuan Zhao, Yanfang Xie, Wenjie Yuan, Dongxiang Li, Shufeng Liu, Bin Zheng and Wanguo Hou
Journal of Materials Chemistry A 2013 vol. 1(Issue 9) pp:1263-1269
Publication Date(Web):08 Jan 2013
DOI:10.1039/C2TB00389A
Hierarchical rope-like structures based on Co–Fe layered double hydroxide (LDH) nanosheets were synthesized by the coprecipitation method from a hexagonal lyotropic liquid crystal (LLC) nanoreactor, and were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and inductively coupled plasma (ICP) analyses. It was found that the rope-like LDH structures were composed of LDH nanosheets with a lateral size of about 200–400 nm and an average thickness of 4.47 nm in the form of face-to-edge interactions. The length and the diameter of the rope-like assemblies were about 3–6 μm and 150–300 nm, respectively, and their aspect ratio was as high as 20. Interestingly, the LDH rope-like assemblies were ordered to form an array with the oriented directions parallel to each other. A formation mechanism for the hierarchical LDH structures in the LLC media was proposed. In addition, the catalytic activity of the hierarchical rope-like LDH assemblies for the oxidation reaction of the typical horseradish peroxidase (HRP) substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), was examined, and results revealed that they had a higher oxidase-like catalytic activity towards the oxidization of TMB by dissolved oxygen. We expect that the hierarchical rope-like LDHs can offer the potential applications in aqueous redox catalysts, biosensors, medical diagnostics and so on.
Co-reporter:Jie Xu, Lin Zhang, Aolin Yin, Wanguo Hou and Ying Yang
Soft Matter 2013 vol. 9(Issue 28) pp:6497-6504
Publication Date(Web):20 May 2013
DOI:10.1039/C3SM50869B
The phase behavior of the ternary system consisting of the hydrophilic ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), toluene and ethanol was investigated. Single-phase microemulsion and multiphase regions were observed in the ternary phase diagram. To the best of our knowledge, this is the first report on nonaqueous IL microemulsions prepared in the absence of traditional surfactants. The microstructures and structural transitions of the microemulsion system were investigated by cyclic voltammetry, pulse field gradient spin-echo nuclear magnetic resonance and electrical conductivity measurements. The microemulsions exhibit IL-in-toluene (IL/O), bicontinuous (BC) and toluene-in-IL (O/IL) microstructures, similarly to traditional surfactant-based microemulsions. The three kinds of microstructures were confirmed from freeze-fracture electron microscopy observations. A pearl necklace-like structure was observed in the BC microemulsion. The polarity of bmimBF4 domains in the IL/O microemulsion was investigated by UV-visible absorption spectroscopy using methyl orange as a probe. It was found that the polarity was lower than that of the bulk bmimBF4, and it increased with increasing bmimBF4 content at a constant toluene–ethanol ratio.
Co-reporter:Jie Xu, Lin Zhang, Chunfang Li, Tianrong Zhan and Wanguo Hou
RSC Advances 2013 vol. 3(Issue 44) pp:21494-21500
Publication Date(Web):10 Sep 2013
DOI:10.1039/C3RA43288B
The phase behavior of a ternary system consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), N,N-dimethylformamide, and water was investigated. Single-phase microemulsion and multiphase regions were observed in the ternary phase diagram. To the best of our knowledge, this is the first report of aqueous IL microemulsions prepared in the absence of traditional surfactants, i.e., surfactant-free microemulsions (SFMEs) containing IL. The microstructures and structural transitions of the aqueous IL SFMEs were investigated using cyclic voltammetry, electrical conductivity, and dynamic laser light scattering techniques. The results showed that the aqueous IL SFMEs exhibit IL-in-water, bicontinuous, and water-in-IL microstructures, similar to the case of traditional surfactant-based microemulsions. The three kinds of microstructures were confirmed from freeze-fracture electron microscopy observations. Ultraviolet-visible and fluorescence spectroscopies were used to examine the polarities of microdomains in the microemulsions, using methyl orange and pyrene, respectively, as probes. It was found that these two techniques can be used to identify the microstructures and microstructural transitions of the aqueous IL microemulsions.
Co-reporter:Xiujiang Pang, Xiuming Ma, Dongxiang Li, Wanguo Hou
Solid State Sciences 2013 Volume 16() pp:71-75
Publication Date(Web):February 2013
DOI:10.1016/j.solidstatesciences.2012.10.008
10-Hydroxycamptothecin (HCPT) as a hydrophobic anticancer drug brings many challenges in the clinical applications due to its poor water solubility and the presence of a chemically unstable lactone ring. In this work, the nanocomposites of HCPT intercalated layered double hydroxide (LDH) were prepared by a secondary intercalation method, and the encapsulated HCPT could keep the biologically active lactone form. A Zn–Al–NO3 LDH was pillared with sebacate anions by a co-precipitation method in an aqueous medium, and then HCPT was intercalated into the LDH's gallery via hydrophobic interaction in an ethanol medium. The parallel alkyl chains of perpendicularly arranged sebacate anions in the LDH gallery provide a hydrophobic space for the drug intercalation. The in vitro release kinetics of HCPT from the nanocomposites could be fitted with the pseudo-second-order kinetic model, and the diffusion of HCPT through the LDH particles played an important role in controlling the drug release. The nanocomposites can be considered as a potential drug delivery system.Graphical abstractHighlights► The HCPT–SC–LDH composites was successfully synthesied by a secondary intercalation method. ► The encapsulated HCPT could keep the biologically active lactone structure. ► The obtained drug-LDH nanocomposite showed a good drug loading amount and obvious controlled release effect.
Co-reporter:Xiaomei Lu, Liming Meng, Haiping Li, Na Du, Renjie Zhang, Wanguo Hou
Materials Research Bulletin 2013 48(4) pp: 1512-1517
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.12.057
Co-reporter:Jie Xu;Lin Zhang;Dongxiang Li;Jikuan Zhao;Wanguo Hou
Colloid and Polymer Science 2013 Volume 291( Issue 11) pp:2515-2521
Publication Date(Web):2013 November
DOI:10.1007/s00396-013-2996-8
The synthesis of Mg2Al-Cl layered double hydroxide (LDH) nanosheets in a surfactant-free reverse microemulsion is described. The microemulsion was composed of toluene, isopropanol, and an aqueous solution as the dispersed phase. An aqueous LDH nanosheet dispersion was obtained by a double-microemulsion technique. LDH nanosheets were characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses. The LDH nanosheets consisted of a single brucite layer without any loading of organic molecules. To the best of our knowledge, this is the first report of a naked LDH monolayer aqueous dispersion being directly obtained. The LDH monolayers can be used as building blocks for LDH-based functional materials.
Co-reporter:Ling-Xi Zhao;Shu-E Song;Na Du
Colloid and Polymer Science 2013 Volume 291( Issue 3) pp:541-550
Publication Date(Web):2013 March
DOI:10.1007/s00396-012-2742-7
During study of the adsorption isotherms at solid–liquid interfaces, a sorbent concentration effect (Cs-effect) phenomenon was observed. In order to describe the Cs-effect, we proposed a new adsorption model, i.e., surface component activity (SCA) model. It supposes that the interaction between the sorbent particles exists in the real adsorption system, which induces the deviation of a real adsorption system from an ideal one. It is the deviation that induces the emerging of the Cs-effect. Based on the SCA model, the activity coefficient of adsorption sites should be a function of the sorbent concentration (Cs), and a Cs-dependent Freundlich equation (Freundlich-SCA equation) was derived. It was confirmed that the Freundlich-SCA equation can describe the Cs-effect observed in adsorption experiments. Its parameters (nS and KS) can be simulated with experimental adsorption data and are independent of Cs. Thus, these parameters obtained at given Cs values can be used to predict the adsorption behavior of the adsorbate at any Cs value.
Co-reporter:Chunfang Li;Dongxiang Li;Chuanlong Qiu;Wanguo Hou
Journal of Polymer Research 2013 Volume 20( Issue 8) pp:
Publication Date(Web):2013 August
DOI:10.1007/s10965-013-0204-7
Amphiphilic dendritic macromolecules are suitable for the noncovalent encapsulation of guest molecules and could potentially be applied in drug-delivery systems. In this work, amphiphilic carbosilane dendrimers with peripheral poly(ethylene glycol) (PEG) units were synthesized using a hydrosilylation reaction, and their encapsulation properties were studied by fluorescence spectroscopy, using pyrene as the probe molecule. The results showed that the encapsulating capacity of the dendrimers increased as the number of PEG units increased, and that it also depended to some degree on the dendrimer generation.
Co-reporter:Jie Xu, Aolin Yin, Jikuan Zhao, Dongxiang Li, and Wanguo Hou
The Journal of Physical Chemistry B 2013 Volume 117(Issue 1) pp:450-456
Publication Date(Web):December 11, 2012
DOI:10.1021/jp310282a
Generally, a microemulsion consists of oil, water, surfactant, and sometimes cosurfactant. Herein, we report a surfactant-free microemulsion (denoted as SFME), consisting of oleic acid (oil phase), water, and n-propanol without the amphiphilic molecular structure of a traditional surfactant. The phase behavior of the ternary system was investigated, showing that there were a single-phase microemulsion region and a multiphase region in the ternary phase diagram. The electrical conductivity measurement was employed to investigate the microregions of the single-phase microemulsion region, and three different microregions, that is, water-in-oleic acid (W/O), a bicontinuous (B.C.) region, and oleic acid-in-water (O/W), were identified, which were further confirmed by freeze-fracture and cryogenic transmission electron microscopy (FF-TEM and Cryo-TEM) observations. The polarity and the salt solubility of water domains in the W/O SFME were investigated by UV–visible spectroscopy using methyl orange and potassium ferricyanide as probes, respectively. Experimental results showed that the water domains in the W/O microemulsion had a lower polarity than bulk water and a normal solubility for salt species, indicating that the SFMEs have much significance in the preparation of various nanomaterials.
Co-reporter:Haiping Li, Renfu Chen, Xiaomei Lu, Wanguo Hou
Carbohydrate Polymers 2012 Volume 90(Issue 3) pp:1330-1336
Publication Date(Web):15 October 2012
DOI:10.1016/j.carbpol.2012.07.001
Rheological properties of aqueous solution containing xanthan gum (XG) and cationic cellulose JR400 were investigated at different composition ratio, shear rate, pH and electrolyte concentrations. It was found that the mixing of XG and JR400 can induce a viscosity-increasing effect for the mixed solution. As the concentration fraction (fJR) of JR400 in the mixed solution increases from 0 to 0.40 with the total polymer concentration (ct) of 1%, the solution transforms from an elastic fluid into a viscoelastic one, while as fJR decreases from 1 to 0.78, the solution transforms from a viscous fluid into a viscoelastic one. At pH 5–10, both the viscosity and elasticity of XG/JR400 mixture (fJR = 0.15) are independent of pH and the viscosity-increasing effect is obvious. Outside this pH range, the viscosity, elasticity and viscosity-increasing effect of the mixture decrease. The increase of added NaCl concentration and shear rate can induce the decrease of viscosity, elasticity and viscosity-increasing effect of the XG/JR400 mixture.Highlights► Mixing of xanthan gum and JR400 causes the increase of dynamic modulus of their mixed solutions. ► Mixing-induced viscosity increase is obvious at pH 5–10 for the mixed solutions. ► The viscosity-increasing effect can be weakened severely with increasing shear rate and electrolyte concentration.
Co-reporter:Haiping Li, Wanguo Hou, Xiuzhi Li
Carbohydrate Polymers 2012 Volume 89(Issue 1) pp:24-30
Publication Date(Web):5 June 2012
DOI:10.1016/j.carbpol.2012.02.022
The electrostatic and hydrogen bonding interactions between xanthan gum (XG) and semisynthetic cationic cellulose (JR400) in aqueous solution are investigated via stability map, FT-IR spectra, thermogravimetric analysis, potentiometric measurement and rheological method. The stability map shows three regions, a stable region with XG as the major component, a flocculated region and another stable region with JR400 as the major component. The stability of mixing system depends on both the concentration fraction of JR400 (fJR) and the overlapping concentrations of these two polymers. In the region near the stoichiometric fJR, the mixture shows stoichiometric flocculation, which is independent of the total polymer concentration. However, in the regions away from the stoichiometric fJR, the mixtures are stable when the concentration of major polymer component is higher than its overlapping concentration. In stable regions, the electrostatic and hydrogen bonding interactions can enhance the viscosity of mixing system at appropriate fJR values.Highlights► Electrostatic and hydrogen bonding interactions between xanthan gum and cationic cellulose JR400 are firstly confirmed. ► Viscosity of xanthan gum/JR400 mixture can be enhanced after mixing. ► Average molecular weight of mixture is higher than that of reported oppositely charge polyelectrolyte mixtures.
Co-reporter:Gang Qiang Wan, Dong Xiang Li, Chun Fang Li, Jie Xu, Wan Guo Hou
Chinese Chemical Letters 2012 Volume 23(Issue 12) pp:1415-1418
Publication Date(Web):December 2012
DOI:10.1016/j.cclet.2012.10.020
Zn–Al layered double hydroxide (LDH) was used as precursor to produce ZnO nanostructures through dissolution of aluminum hydroxide in caustic soda. The Zn–Al LDH could transform into different nanostructures of ZnO on LDH nanosheets and even pure ZnO nanorods under various NaOH concentration. The formed ZnO nanorods vertically aligned on both LDH sides. UV–vis diverse reflectance spectra show that the obtained ZnO nanorods have a band gap of approximately 3.05 eV. Such ZnO/LDH nanostructures might be used as photocatalyst in the organic pollutant decomposition.
Co-reporter:Tianrong Zhan, Yaqing Guo, Li Xu, Weili Zhang, Wei Sun, Wanguo Hou
Talanta 2012 Volume 94() pp:189-194
Publication Date(Web):30 May 2012
DOI:10.1016/j.talanta.2012.03.018
A novel biocompatible nanocomposite prepared by Mg2Al–Cl layered double hydroxide (LDH) and ionic liquid (IL) 1-carboxyl-methyl-3-methylimidazolium tetrafluoroborate was used as the matrix for the immobilization of myoglobin (Mb). The IL-LDH-Mb composite was characterized by UV–vis adsorption spectroscopy and the results indicated that Mb retained its native structure in the IL-LDH nanocomposite. The IL-LDH-Mb bionanocomposite was modified on the surface of carbon ionic liquid electrode to get an Mb modified electrode. Electrochemical experiments showed that direct electrochemistry of Mb in the composite was realized with a pair of well-defined redox peaks appeared, which could be attributed to the specific microenvironment provided by layer structured LDH and high ionic conductive IL present for Mb molecule. The modified electrode exhibited good direct electrocatalytic ability to the reduction of trichloroacetic acid and hydrogen peroxide with good stability and reproducibility. Different kinds of real samples were detected by the modified electrode with satisfactory results. So the IL-LDH nanocomposite provided a novel and efficient platform for the immobilization of enzymes, which had potential applications in the fabrication of third-generation biosensors.
Co-reporter:Ling-Xi Zhao, Wan-Guo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 396() pp:29-34
Publication Date(Web):20 February 2012
DOI:10.1016/j.colsurfa.2011.12.026
During studying the distribution of pollutants between the aqueous and particulate phases, an anomalous Cs-effect phenomenon, namely, the experimentally measured partition coefficient (Kp) value of a given system decreased with increasing the sorbent concentration (Cs), was observed in a number of adsorption systems. Classical Langmuir model cannot predict the Cs-effect. In this paper, a surface component activity (SCA) model was proposed, which suggests that surface component (adsorption site or adsorbed solute) activity coefficient is a function of Cs because of the existence of adsorbent particle–particle interactions. A semi-empirical Cs-dependent function of partition coefficient was derived, and it can predict the Cs-dependence of partition coefficient for both organic compounds and heavy metals.Graphical abstractA surface component activity model was proposed to predict the sorbent concentration (Cs) dependence of partition coefficient, and a semi-empirical Cs-dependent function of partition coefficient was derived.Highlights► A surface component activity (SCA) model to describe the Cs-effect of partition coefficient was proposed. ► A semi-empirical Cs-dependent function of partition coefficient was derived. ► The function can predict the Cs-dependence of partition coefficient for both organic compounds and heavy metals.
Co-reporter:Hai-ping Li, Wan-guo Hou, Yu-zhong Zhang
Carbohydrate Polymers 2011 Volume 84(Issue 3) pp:1117-1125
Publication Date(Web):17 March 2011
DOI:10.1016/j.carbpol.2010.12.072
The rheological properties, such as shear flow behavior, thixotropy and viscoelasticity, of aqueous solution of a new type of exopolysaccharide (SM-A87 EPS) secreted by a deep-sea mesophilic bacterium were investigated using shear flow and dynamic rheological measurements. For the SM-A87 EPS solutions, the overlapping concentration C* and crossover concentration C** were confirmed to be 0.95 g/L and 4.99 g/L respectively by the concentration-dependences of rheological parameters, such as equilibrium viscosity, thixotropic strength, static and dynamic stress, critical shear rate, and storage modulus in the linear viscoelastic region besides the zero-shear viscosity of solutions. At concentrations higher than C*, the solutions exhibited a static stress, a dominant elastic behavior and a stronger absolute positive thixotropic strength. Otherwise, at concentrations lower than C*, no static stress, a dominant viscous behavior and a weaker absolute positive thixotropic strength were exhibited. The SM-A87 EPS solutions may be used as enhanced oil recovery system.
Co-reporter:Hongqian Nie;Shue Song;Wanguo Hou
Chinese Journal of Chemistry 2011 Volume 29( Issue 7) pp:1373-1379
Publication Date(Web):
DOI:10.1002/cjoc.201180246
Abstract
This paper reports that structurally positively charged layered double hydroxides (LDHs) nanoparticles induce the vesicle formation in a mixture of a zwitterionic surfactant, lauryl sulfonate betaine (LSB), and an anionic surfactant, sodium dodecyl benzenesulfonate (SDBS). The existence of vesicles was demonstrated by negative-staining (NS-TEM) and freeze-fracture (FF-TEM) transmission electron microscopy and confocal laser scanning microscopy (CLSM). The size of vesicles increased with the increase of volume ratio (Q) of Mg3Al-LDHs sol to the SDBS/LSB solution. A new composite of LDHs nanoparticles encapsulated in vesicles was formed. A possible mechanism of LDHs-induced vesicle formation was suggested. The positive charged LDHs surface attracted negatively charged micelles or free amphiphilic molecules, which facilitated their aggregation into a bilayer membrane. The bilayer membranes could be closed to form vesicles that have LDHs particles encapsulated. It was also found that an adsorbed compound layer of LSB and SDBS micelles or molecules on the LDHs surface played a key role in the vesicle formation.
Co-reporter:Yunbo Zang;Wanguo Hou;Jie Xu
Chinese Journal of Chemistry 2011 Volume 29( Issue 4) pp:847-852
Publication Date(Web):
DOI:10.1002/cjoc.201190168
Abstract
Hydrotalcite-like compound (HTlc) with a Mg/Al molar ratio of 2:1 was synthesized by using a coprecipitation method and the sorption removal of Cu(II) by the Mg-Al HTlc sample from CuSO4 solution was investigated. It was found that the Mg-Al HTlc showed a good sorption ability for Cu(II) from CuSO4 solution, indicating that the use of hydrotalcite-like compounds as promising inorganic sorbents for the removal of heavy metal ions from water is possible. The sorption kinetics and the sorption isotherm of Cu(II) on the HTlc obeyed the pseudo-second order kinetic model and Langmuir equation, respectively. The percent removal of Cu(II) by the HTlc was strongly dependent on the initial pH of bulk solution. It increased sharply with the increase of initial pH value in the range of 5–7, and was relatively small in the initial pH range of 4–5, while it reached about 100% after initial pH was higher than 7. The presence of AlCl3 might obviously lower the equilibrium sorption amount (qe) of Cu(II) on the HTlc. However, the presences of NaCl and MgCl2 might increase the qe. The presences of ligands (citric acid and EDTA) in the studied concentration range might obviously decrease the qe of Cu(II) on the HTlc. The removal mechanism of Cu(II) cations by HTlc in the presence of SO42− anions may be attributed to the surface-induced precipitation of Cu(II) hydroxides and the surface complex adsorption by the linking effect of SO42− between the HTlc and Cu(II) cations, and the removal ability arising from the surface-induced precipitation is much higher than that from the linking effect of SO42−.
Co-reporter:Tianrong Zhan, Lili Cao, Wei Sun and Wanguo Hou
Analytical Methods 2011 vol. 3(Issue 11) pp:2651-2656
Publication Date(Web):07 Oct 2011
DOI:10.1039/C1AY05454F
In this paper an ionic liquid (IL) 1-butylpyridinium hexafluorophosphate (BPPF6) modified carbon paste electrode was constructed and further used to establish a sensitive method for the detection of 5-fluoro-1H-pyrimidine-2 (5-FU). Compared with the carbon paste electrode (CPE), a single well-defined irreversible oxidation peak of 5-FU appeared on the IL-CPE with a great improvement of the electrochemical response, which was due to the presence of a high ionic conductive ionic liquid in the electrode that exhibited accumulation and electrocatalytic ability. The electrochemical parameters of 5-FU on the IL-CPE were calculated with the electron transfer coefficient (α) as 0.62 and the diffusional coefficient (D) as 7.02 × 10−5 cm2 s−1. Under the optimal conditions, the oxidation peak current was linear to 5-FU concentration in the range from 5.0 × 10−7 to 8.0 × 10−4 mol L−1 with a detection limit of 1.3 × 10−8 mol L−1 (3σ). Good selectivity to 5-FU detection was observed without the interference of coexisting substances and the method was further applied to determination in injection samples with satisfactory results.
Co-reporter:Dongxiang Li, Xinjie Xu, Jie Xu, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 384(1–3) pp:585-591
Publication Date(Web):5 July 2011
DOI:10.1016/j.colsurfa.2011.05.012
The surface modification of the layered double hydroxides (LDHs) is of much importance for the purposes of the nanoparticle stability, dispersity and biocompatibility. Herein, we reported the fabrication and dispersible properties of surface modified LDHs by poly(ethylene glycol) (PEG) derivatives. First, Mg–Al LDHs were incubated with sulfate or carboxylate-terminated poly(ethylene glycol) (PEG) to fabricate PEG haired LDHs. The pristine LDH particles were truncated into smooth pie-like disks and their Zeta potential reversed to a highly negative value after the surface modification. The obtained PEG/LDH nanocomposites displayed a highly enhanced stability and dispersity due to the polymer steric hindrance and the electrostatic repulse. The PEG haired LDHs might be considered as a multifunctional model vehicle in biodelivery applications in the next applications due to the biocompatible polymer shells.Graphical abstractThe surface grafting of Mg–Al layered double hydroxides was performed using anionic poly(ethylene glycol) derivatives to fabricate poly(ethylene glycol)-haired nanocomposites with enhanced stability, redispersity and biocompatibility.Highlights► Biocompatible poly(ethylene glycol) was grafted onto the surface of layered double hydroxides. ► Polymer presence truncated the particle edges and highly enhanced the particle dispersity. ► Reversed surface charging reveals the multiple interaction forces at the PEG/LDH interface.
Co-reporter:Hongwei Che;Shuhua Han;Wanguo Hou;Aifeng Liu;Shasha Wang
Journal of Porous Materials 2011 Volume 18( Issue 1) pp:57-67
Publication Date(Web):2011/02/01
DOI:10.1007/s10934-010-9356-6
A novel strategy involving the combination of soft-templating and solid–liquid method (CSSL) is presented to synthesize mesoporous nanocrystalline zirconia with high specific surface area, that is, the mesostructured zirconia hybrid is firstly synthesized via cooperative assembly between zirconium sulphate as inorganic precursor and 1-hexadecyl-3-methylimidazolium bromide (C16mim+Br−) as the structure-directing agent, and subsequently ground with solid magnesium nitrate salt followed by heat-treatment in air. The resulting zirconia material after calcination at 600 °C possesses a wormlike arrangement of mesopores surrounded by tetragonal ZrO2 nanocrystallites of ca. 2.3 nm. The BET surface area is 255 m2/g and the pore size is ca. 4.3 nm. However, no mesoporous structure exists in the obtained zirconia material via the simple soft-templating method at the same calcination temperature. Photoluminescence (PL) spectra of the obtained mesoporous nanocrystalline ZrO2 show a strong emission peak at ca. 394 nm under UV excitation of 250 nm wavelength.
Co-reporter:Hong-Qian Nie
Colloid and Polymer Science 2011 Volume 289( Issue 7) pp:775-782
Publication Date(Web):2011 May
DOI:10.1007/s00396-011-2391-2
In this paper, it is reported that positively charged Mg3Al layered double hydroxide (LDH) nanoparticles can induce the spontaneous formation of vesicles in micelle solution of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) with a mass ratio of 8:2. The formation of vesicles was demonstrated by negative-staining transmission electron microscopy observations. The size of the vesicles increased with the increase in the concentration of Mg3Al-LDH nanoparticles. A composite of LDH nanoparticles encapsulated in vesicles was formed. A possible mechanism of LDH-induced vesicle formation was suggested. The positively charged LDH surface attracts negatively charged micelles or free amphiphilic molecules, which facilitates their aggregation into bilayer patches. These bilayer patches connect to each other and finally close to form vesicles. It was also found that an adsorbed compound layer of SDS and DTAB micelles or molecules on the LDHs surface played a key role in vesicle formation.
Co-reporter:Tianrong Zhan, Mengying Xi, Yan Wang, Wei Sun, Wanguo Hou
Journal of Colloid and Interface Science 2010 Volume 346(Issue 1) pp:188-193
Publication Date(Web):1 June 2010
DOI:10.1016/j.jcis.2010.02.007
A biocomposite material composed of sodium alginate (SA), Fe2O3 nanoparticles, and ionic liquid 1-decyl-3-methylimidazolium bromide ([DMIM]Br) was fabricated and used for the immobilization of myoglobin (Mb) on the surface of a carbon ionic liquid electrode (CILE). The CILE was fabricated by mixing graphite powder with ionic liquid N-butylpyridinium hexafluorophosphate (BPPF6) together. UV–Vis absorption and FTIR spectroscopic results indicated that Mb retained its native structure in the composite material. A pair of well-defined redox peaks appeared on the cyclic voltammogram in pH 7.0 phosphate buffer solution (PBS) with the formal peak potential (E0′) at −0.256 V (versus SCE), which was the typical electrochemical behavior of Mb heme Fe(III)/Fe(II) redox couples. The Mb-modified electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid (TCA) and NaNO2 with wide linear range, good sensitivity, and reproducibility. The calibration range for TCA detection was between 0.6 and 12.0 mmol L−1 with the linear regression equation as Iss (μA) = 42.44C (mmol L−1) + 50.57 and a detection limit of 0.4 mmol L−1 (3σ). The Mb-modified electrode also applied to NaNO2 determination in the concentration range from 4.0 to 100.0 mmol L−1 with a detection limit of 1.3 mmol L−1 (3σ). So the proposed electrode has potential applications as third-generation biosensors.A pair of well-defined redox peaks appeared on the cyclic voltammogram of SA–Mb–IL–Fe2O3/CILE (d) in pH 7.0 phosphate buffer solution at a scan rate of 100 mV s−1.
Co-reporter:Chun-Fang Li, Xian-Zi Dong, Dong-Xiang Li, Wei-Qiang Chen, Zhen-Sheng Zhao, Wan-Guo Hou, Xuan-Ming Duan
Journal of Luminescence 2010 Volume 130(Issue 4) pp:544-548
Publication Date(Web):April 2010
DOI:10.1016/j.jlumin.2009.10.028
In this article, a carbosilane dendrimer functionalized in the periphery with fluorescein units was prepared, and the optical property of the fluorescent dendrimer as gain medium was investigated. It was found that the dendrimer consisted of a methylphenylsilane core with 16 fluorescein units in its periphery. The dendrimer exhibits high optical-gain enhancement in methanol solution and laser emission was observed, which is located at 527 nm above the lasing threshold of 0.9 mJ/pulse.
Co-reporter:Fei Song, Jie Xu, Wan Guo Hou
Chinese Chemical Letters 2010 Volume 21(Issue 7) pp:880-883
Publication Date(Web):July 2010
DOI:10.1016/j.cclet.2010.01.029
Generally, a microemulsion consists of oil, water, surfactant and sometimes cosurfactant. Herein, we report a novel surfactant-free microemulsion (denoted as SFME) composed of benzene, water and ethanol without the amphiphilic molecular structure of traditional surfactant. The phase behavior of the ternary system was investigated, finding that there were a single-phase region and a two-phase region in ternary phase diagram. The electrical conductivity measurement was employed to investigate the microregion of the single-phase region, and a bicontinuous microregion and a benzene-in-water (O/W) microemulsion microregion were identified, which was confirmed by freeze-fracture transmission electron microscopy (FF-TEM) observations. The sizes of the microemulsion droplets are in the range of 20–50 nm.
Co-reporter:Lun Dong, Li Yan, Wan-Guo Hou, Shao-Jie Liu
Journal of Solid State Chemistry 2010 Volume 183(Issue 8) pp:1811-1816
Publication Date(Web):August 2010
DOI:10.1016/j.jssc.2010.05.035
A simple method, reconstruction of calcinated layered double hydroxides (CLDH) in an organic (ethanol)–water mixed solvent medium containing drug, was developed to intercalate partially a non-ionic and poorly water-soluble drug (camptothecin) into the gallery of layered double hydroxides (LDHs) to form the drug–LDH composites. The purpose of choosing organic–water mixed solvent is to increase remarkably the solubility of camptothecin (CPT) in the reconstruction medium. A probable morphology of CPT molecules in the gallery of LDHs is that CPT molecules arrange as monolayer with the long axis parallel to the LDH layers. The in vitro drug release from the composites was remarkably lower than that from the corresponding physical mixture, which shows these drug–inorganic composites can be used as a potential drug delivery system.A simple method, reconstruction of calcinated LDHs in an organic–water medium containing drug, was developed to intercalate non-ionic and poorly water-soluble camptothecin into the gallery of LDHs.
Co-reporter:Chunfang Li, Dongxiang Li, Zhen-Sheng Zhao, Xuan-Ming Duan, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 366(1–3) pp:45-49
Publication Date(Web):20 August 2010
DOI:10.1016/j.colsurfa.2010.05.013
In this paper, platinum nanoparticles were prepared in the hydrosilylation reaction, in which carbosilane dendrimer was used as capping agent and stabilizer. UV–vis spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were employed to characterize the reaction system and the obtained Pt nanoparticles. The high SiH/Pt ratios could accelerate the formation of Pt nanoparticles in hydrosilylation reaction. When the hydrosilane was excess in the reaction, the formed Pt nanoparticles were first capped by hydrosilane molecules via Pt–Si bonds and then stabilized by dendrimers. While under the condition of excess olefin, the Pt nanoparticles were directly capped and stabilized by dendrimers via Pt–C bonds. The formed Pt nanoparticles had a good dispersibility with different size.
Co-reporter:Dongxiang Li, Chunfang Li, Gangqiang Wan, Wanguo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 372(1–3) pp:1-8
Publication Date(Web):3 December 2010
DOI:10.1016/j.colsurfa.2010.08.055
Polymeric nanovesicles self-assembled by amphiphilic block copolymers have attracted much attention in the biodelivery of hydrophobic drugs. In this paper, the amphiphilic copolymers of poly(dimethylsiloxane)-block-poly(ethylene glycol) (PDMS-b-PEG) were synthesized to fabricate polymeric nanovesicles in mixed solvent of THF and water. Dynamic light scattering (DLS) were used to monitor the assembling process of the block copolymers, and the aqueous nanovesicle solution could be obtained by a slow evaporation of THF. The vesicle size could be adjusted according to the volume ratio of water to THF and also the concentration of copolymers in the assembly. Higher water content in the mixed solvent produced smaller vesicles, while higher polymer concentration caused the formation of larger vesicles. The hydrophobic domain of the obtained nanovesicles could encapsulate hydrophobic drugs based on the hydrophobic interaction, in which the nanovesicles acted as water-soluble hydrophobic nanotanks. The drug encapsulation capability of these nanovesicles might exhibit a significant potential as drug nanocarriers in biodelivery system.Polymeric nanovesicles of amphiphilic poly(dimethylsiloxane)-b-poly(ethylene glycol) (PDMS-b-PEG) copolymers were self-assembled to encapsulate hydrophobic drugs as water-soluble nanotanks. The vesicle size can be adjusted according to the volume ratio of water to THF and also the polymer concentration in the self-assembling process. The hydrophobic domain of the polymeric nanovesicles can encapsulate hydrophobic drugs based on the hydrophobic interaction, displaying a significant potential in biodelivery systems for hydrophobic drugs.
Co-reporter:Tianrong Zhan, Xiaoying Sun, Xiuzhen Wang, Wei Sun, Wanguo Hou
Talanta 2010 Volume 82(Issue 5) pp:1853-1857
Publication Date(Web):15 October 2010
DOI:10.1016/j.talanta.2010.07.083
An ionic liquid (IL) modified carbon ceramic electrode (CCE) was designed and further used for the voltammetric detection of rutin in this paper. IL-CCE was prepared by mixing graphite powder with 1-butyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) doped silicate sol–gel matrix together and further characterized by different methods. Then electrochemical behaviors of rutin on the IL-CCE were investigated by different electrochemical methods such as cyclic voltammetry and differential pulse voltammetry (DPV). Due to the presence of IL in the CCE, an enhanced electrochemical response of rutin appeared with a pair of well-defined redox peaks in pH 2.5 phosphate buffer solution (PBS). The electrochemical behaviors of rutin on the IL-CCE were carefully investigated. Under the selected conditions the oxidation peak currents exhibited good linear relationship with the rutin concentration in the range from 0.3 to 100.0 μmol/L with the detection limit as 0.09 μmol/L (3σ). The proposed method was further applied to the rutin tablets sample detection with satisfactory results.
Co-reporter:Depeng QIU;Yonghai LI;Xiying FU;Zhen JIANG;Xinyan ZHAO;Tian WANG;Wanguo HOU
Chinese Journal of Chemistry 2009 Volume 27( Issue 3) pp:445-451
Publication Date(Web):
DOI:10.1002/cjoc.200990073
Abstract
The intercalation of avermectin (AVM) into sodium dodecyl sulfate (SDS) modified hydrotalcite-like compounds (HTlc) was carried out using an evaporating solvent enhanced intercalation method to obtain AVM-SDS-HTlc nanohybrids. It was found that the nanohybrids could well control the release of avermectin, showing the nanohybrids are a potential pesticide controlled-release formulation. The release of avermectin from AVM-SDS-HTlc nanohybrids is dependent on the pH, temperature and the presence of electrolyte in release medium. Acidic medium and higher temperature and the presence of electrolytes may induce the higher release rate of avermectin. The release process of avermectin from AVM-SDS-HTlc nanohybrids can be described by pseudo-first-order release kinetics, and the activation energy of release is 279 kJ/mol.
Co-reporter:Xuefeng Liang;Wanguo Hou;Jie Xu
Chinese Journal of Chemistry 2009 Volume 27( Issue 10) pp:1981-1988
Publication Date(Web):
DOI:10.1002/cjoc.200990333
Abstract
Mg-Fe layered double hydroxide (LDH) with a Mg/Fe molar ratio of 3:1 was synthesized by using a coprecipitation method and the sorption removal of Pb(II) by the LDH sample from Pb(NO3)2 solution was investigated. It was found that Mg-Fe LDH showed a good sorption ability for Pb(II) from Pb(NO3)2 solution, indicating that the use of LDH as a promising inorganic sorbent for the removal of heavy metal ions is possible. The sorption kinetics and the sorption isotherm of Pb(II) on the LDH sample obeyed the pseudo-second order kinetic model and Aranovich-Donohue equation, respectively. The sorption mechanism of Pb(II) on the LDH may be attributed to the surface-induced precipitation and the chemical binding adsorption, and the removal ability arising from the surface-induced precipitation is much higher than that from the chemical binding adsorption.
Co-reporter:Depeng Qiu;Wanguo Hou;Jie Xu;Jianqiang Liu;Shaojie Liu
Chinese Journal of Chemistry 2009 Volume 27( Issue 10) pp:1879-1885
Publication Date(Web):
DOI:10.1002/cjoc.200990315
Abstract
Hydrotalcite-like compounds (HTlc) were first modified by sodium dodecyl sulfate (SDS), then the intercalation of imidacloprid (IM) into modified HTlc was carried out in mixed solvent of toluene/ethanol by an evaporating solvent enhanced intercalation method, obtaining IM-SDS-HTlc nanohybrids. It was found that the nanohybrids could well control the release of imidacloprid, demonstrating that the nanohybrids are a potential pesticide controlled-release formulation. The release of imidacloprid from IM-SDS-HTlc nanohybrids is dependent on the pH and the presence of electrolyte in release medium. Acidic medium and the presence of electrolytes induce the higher release rate of imidacloprid. The release process of imidacloprid from IM-SDS-HTlc nanohybrids can be described by pseudo-second-order release kinetics.
Co-reporter:Quan Zhenlan, Yang Heng, Zheng Bin, Hou Wanguo
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 348(1–3) pp:164-169
Publication Date(Web):20 September 2009
DOI:10.1016/j.colsurfa.2009.07.004
In this paper, two charge-neutral and poorly water-soluble bactericides (BC), hexaconazole and triadimenol, were first encapsulated in micelles derived from anionic surfactant, calcium dodecylbenzenesulfonate (DBS), and then were successfully intercalated into the gallery of Mg–Al layered double hydroxides (LDHs) by using ion exchange, coprecipitation and reconstruction methods, respectively, to obtain BC–LDHs nanohybrids. The loading amounts of hexaconazole-LDHs nanohybrids are obviously higher than those of triadimenol-LDHs nanohybrids. The release kinetics of bactericides from the nanohybrids was investigated. It was found that the bactericide release kinetic processes of the nanohybrids can be described with pseudo-second-order model. The initial release rates and equilibrium percent releases of the nanohybrids are obviously dependent of synthesis methods. The nanohybrids can well control the release of bactericides, showing they are a potential pesticide controlled-release formulation.
Co-reporter:De-peng Qiu, Wan-guo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 336(1–3) pp:12-17
Publication Date(Web):20 March 2009
DOI:10.1016/j.colsurfa.2008.11.028
In this paper, the intercalation of indole-3-butyric acid (IBA) into hydrotalcite-like compounds (HTlc) was carried out using anion exchange and reconstruction method to obtain IBA–HTlc nanohybrids. The release kinetics of IBA from the nanohybrids was investigated in various conditions to study the effects of some factors namely IBA loading amount, synthesis method, electrolyte and temperature. It was found that the nanohybrids can well control the release of IBA, showing that the nanohybrids are a potential pesticide-controlled release formulation. The release of IBA from the nanohybrids prepared by reconstruction was slower than that of the nanohybrids prepared by anion exchange. The presence of electrolyte and the higher temperature would induce quicker release of IBA. For the nanohybrid samples synthesized by anion exchange method, the release rate of IBA increased with the increase of IBA loading amount. The release process of IBA from IBA–HTlc nanohybrids may be described by pseudo-second-order release kinetics.
Co-reporter:Chun-Xia LIU;Yan LI;Li-Fang LI
Chinese Journal of Chemistry 2008 Volume 26( Issue 10) pp:1806-1810
Publication Date(Web):
DOI:10.1002/cjoc.200890325
Abstract
The intercalation of camptothecin (CPT) into a layered inorganic host, Mg-Al layered double hydroxide (LDH), was carried out using a coprecipitation method to obtain CPT-LDH nanohybrids. It was found that the intercalated amounts (Ain) of CPT-LDH nanohybrids were remarkably dependent on the molar ratios (RC/M) of CPT to metal ions in raw materials. The Ain value increases with the RC/M value increasing. According to the gallery heights of CPT-LDH and sizes of CPT molecule, a probably morphology of CPT molecules in the gallery of LDH was suggested that the horizontal-arranged monolayer and vertical-arranged bilayer of CPT molecules coexisted in the interlayer region of LDH. An interesting result was found that the gallery height corresponding to the bilayer of CPT-LDH sample with a high Ain value was remarkably lower than that with low Ain value. The in vitro CPT release examinations from the nanohybrids showed that the CPT-LDH nanohybrids were a potential drug controlled release system. The kinetic analysis showed that the release kinetics of CPT from the nanohybrids obeyed the pseudo-first order kinetic model and the diffusion of CPT through the LDH particle of CPT played an important role in controlling the drug release rate.
Co-reporter:Peng NI
Chinese Journal of Chemistry 2008 Volume 26( Issue 11) pp:1985-1990
Publication Date(Web):
DOI:10.1002/cjoc.200890355
Co-reporter:Peng NI
Chinese Journal of Chemistry 2008 Volume 26( Issue 7) pp:1335-1338
Publication Date(Web):
DOI:10.1002/cjoc.200890243
Abstract
Generally, a microemulsion consists of oil, water, surfactant and sometimes cosurfactant. Herein, for the first time to our knowledge, a novel surfactant-free microemulsion (SFME), consisting of furaldehyde (oil phase), water and N,N-dimethyl formamide (DMF) without the amphiphilic molecular structure of traditional surfactant is reported. The phase behavior of the ternary system was investigated, finding that a single-phase microemulsion region and a two-phase region were formed. The electrical conductivity measurement was employed to investigate the single-phase microemulsion region. On the basis of the percolation theory, the single-phase microemulsion region was identified to consist of three different microregions: furaldehyde-in-water (O/W), bicontinuous region and water-in-furaldehyde (W/O), which were further proved by freeze-fracture transmission electron microscopy (FF-TEM) observations. The diameter of the microemulsion spherical droplets is in the range of 40–70 nm.
Co-reporter:Chunxia Liu, Wanguo Hou, Lifang Li, Yan Li, Shaojie Liu
Journal of Solid State Chemistry 2008 Volume 181(Issue 8) pp:1792-1797
Publication Date(Web):August 2008
DOI:10.1016/j.jssc.2008.03.032
In this paper, the intercalation of 5-fluorocytosine (5-FC) into a layered inorganic host, Zn–Al layered double hydroxide (LDH), has been carried out using coprecipitation method to obtain 5-FC/LDH nanohybrids. The intercalated amount (AIn) of 5-FC into the LDH is remarkably dependent on the molar ratio (RF/M) of 5-FC to metal ions and the pH of coprecipitation system. The morphology of 5-FC molecules in 5-FC/LDH nanohybrids is dependent on the AIn. It is interestingly found that the morphology of the nanohybrid particles may be changed with the increase of RF/M from hexagonal plate particles to threadlike particles. The in vitro drug release from the nanohybrids is remarkably lower than that from the corresponding physical mixture and pristine 5-FC at either pH 4.8 or pH 7.5. In addition, the release rate of 5-FC from the nanohybrid at pH 7.5 is remarkably lower than that at pH 4.8, this is due to a possible difference in the release mechanism. The obtained results show these drug-inorganic nanohybrids can be used as a potential drug delivery system.The 5-fluorocytosine (5-FC) has been intercalated into layered double hydroxide using coprecipitation method. The morphology of 5-FC molecules in obtained nanohybrids was dependent on the intercalated amount of 5-FC. The in vitro drug release from the nanohybrids was remarkably lower than that from the corresponding physical mixture, which shows these drug-inorganic nanohybrids can be used as a potential drug delivery system.
Co-reporter:Yan Li, Wan-Guo Hou, Wei-Qun Zhu
Journal of Colloid and Interface Science 2007 Volume 313(Issue 1) pp:305-314
Publication Date(Web):1 September 2007
DOI:10.1016/j.jcis.2007.03.071
The rheological properties of aqueous suspensions consisting of cationic starch (CS) and positively charged aluminum magnesium hydrotalcite-like compound (HTlc) were investigated. Special emphasis was placed on the thixotropic phenomena. With the increase of mass ratio (R ) of HTlc to CS, the equilibrium viscosity (ηeqηeq) and the consistency coefficient (m ) values of the suspensions increase in the range of neutral and alkaline pH (higher than 6.5) while decrease in the range of acid pH (lower than 6.5). With the increase of pH value, the ηeqηeq and m values of the suspensions in the R range of 0–0.08 studied increase initially and then decrease, appearing a maximum value at about pH 7.41±0.257.41±0.25. The CS/HTlc suspensions display viscid character and the yield point of the suspensions was not observed except the suspension with R=0.08R=0.08 in the pH range of 7.66–9.70, which showed a yield point and viscoelasticity. The CS/HTlc suspensions may display different thixotropic types: negative, complex or positive thixotropy, depending on pH and R value. The thixotropic type of the CS/HTlc suspension may be transformed from negative (pure CS solution), through complex (R=0.02R=0.02), into positive thixotropy (R=0.05R=0.05 and 0.08) with the increase of R in the studied R range of 0–0.08, and the thixotropic strength of the suspensions increases initially and then decreases with pH value in the pH range studied. The mechanism of the thixotropic phenomenon is discussed.Rheological properties of aqueous suspensions containing cationic starch (CS) and hydrotalcite-like compound (HTlc) were investigated. Special emphasis was placed on the thixotropic phenomena.
Co-reporter:Shu-Qin ZHANG
Chinese Journal of Chemistry 2007 Volume 25(Issue 10) pp:1455-1460
Publication Date(Web):16 OCT 2007
DOI:10.1002/cjoc.200790269
Layered double hydroxide (LDH) with a Mg/Al molar ratio of 1:1 was synthesized by using a co-precipitation method and its calcined product (CLDH) was obtained by calcination of the MgAl-LDH at 500 °C. The sorption removal of Pb2+ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb2+ from water. The sorption kinetics and the sorption isotherms of Pb2+ on both LDH and CLDH can be described by the pseudo-second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb2+ on LDH and CLDH are independent of pH in a pH range of about 3–10. The presence of NaNO3 may inhibit the sorption ofPb2+ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb2+ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner-sphere surface complexes and the electrostatic binding adsorption forming the outer-sphere surface complexes. The sorption mechanism of Pb2+ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption.
Co-reporter:Yan-Ni Jiao
Chinese Journal of Chemistry 2007 Volume 25(Issue 6) pp:
Publication Date(Web):14 JUN 2007
DOI:10.1002/cjoc.200790140
The interface electrochemical properties of clay were theoretically analyzed to obtain some relationships among point of zero net charge (PZNC), point of zero net proton charge (PZNPC), intrinsic surface reaction equilibrium constants (K in 1-pK model, Kinta1 and Kinta2 in 2-pK model, *KintNa and *Kint in inert electrolyte chemical binding model) and structural negative charge density (σst) of clay, and some interface electrochemical parameters of kaolinite were measured. The following main conclusions were obtained. For clay possessing structural negative charges, the PZNC independent of electrolyte concentration (c) should exist just as amphoteric solid without structural charges such as oxides or hydroxides. A common intersection point (CIP) should appear among the potentiometric (or acid-base) titration curves at different c and the pH at the CIP should be pHPZNC. A CIP among potentiometric titration curves at different c for kaolinite was observed, and the value of pHPZNC of kaolinite was 2.16. The values of pHPZNPC were decreased with increasing c, which arises from the presence of structural negative charges of kaolinite. In addition, it was observed that a good linear relationship existed between pHPZNPC and lg c. According to the values of pHPZNC and σst measured, the intrinsic surface reaction equilibrium constants, pK and pKinta1 and pKinta2 of 1-pK and 2-pK models could be directly calculated for clay, and the values of pK, pKinta1 and pKinta2 for kaolinite were 2.93, 1.90 and 3.97, respectively. These experimental values of pKinta1 and pKinta2 for kaolinite are obviously lower than those optimized with fitting programs in literatures, which maybe arises from the introduction of a type of permanent negatively charged sites in the models of literatures. An interesting result obtained in this study is that the inert electrolyte chemical binding does not exist for kaolinite, which also arises from the presence of structural negative charges.
Co-reporter:Yan-Ni Jiao, Wan-Guo Hou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 296(1–3) pp:62-66
Publication Date(Web):15 March 2007
DOI:10.1016/j.colsurfa.2006.09.024
A series of Zn–Al and Zn–Al–Fe hydrotalcite-like compounds (HTlc) with different n(Zn)/n(Al)/n(Fe) molar ratios are synthesized by using co-precipitation method. The samples have the following general formula [Zn1−xAlx(OH)2]x+[(OH, Cl)x]x− or [Zn1−x(Al, Fe)x(OH)2]x+[(OH, Cl)x]x−. The points of zero net charge (PZNC) and the intrinsic surface reaction equilibrium constants (pK in 1-pK model and pKa1int, pKa2int in 2-pK model) of the samples were determined by applying potentiometric titration (PT). It is found that the values of the pHPZNC, pK , pKa1int and pKa2int decrease linearly with the increase of structural charge density (σst). The interrelations of the intrinsic equilibrium constants with the pHPZNC are also demonstrated. Similar to oxides without structural charges, the fairly linear dependence of the pK , pKa1int and pKa2int on pHPZNC for HTlc samples with structural positive charges is also observed.
Co-reporter:Wan-Guo Hou;Zhi-Lin Jin
Colloid and Polymer Science 2007 Volume 285( Issue 13) pp:1449-1454
Publication Date(Web):2007 October
DOI:10.1007/s00396-007-1704-y
In this paper, naproxen was intercalated into Zn–Al layered double hydroxides (LDHs) by ion exchange method to obtain naproxen/LDHs nanohybrids. The effects of the contact time, the composition, and the structural charge density (σS,T) and the specific surface area of LDHs, and pH value on the uptake of naproxen on LDHs, and the release of naproxen from the naproxen/LDHs nanohybrids were investigated. The adsorption isotherm curves of naproxen on the LDHs obey the Langmuir equation, and apparent monolayer capacity (Am) in units of mmol m−2 increases with the increase of the σS,T value of the LDHs samples. The release rate of naproxen from the naproxen/LDHs nanohybrids decreases with the increase of the σS,T value of the LDHs samples and is much lower than that of naproxen troche, indicating that the naproxen/LDHs nanohybrid is an efficient drug-controlled release system. In the pH range of 6~11.5, the uptake amount (Aeq) of naproxen on the LDHs decreases with the increase of pH value. The Am values of LDHs(Cl−) are much higher than that of \( {\text{LDHs}}{\left( {{\text{CO}}^{{2 - }}_{3} } \right)} \), which may contribute to that LDHs(Cl−), which has a stronger anion exchange ability than \( {\text{LDHs}}{\left( {{\text{CO}}^{{2 - }}_{3} } \right)} \). The naproxen molecules are possibly adsorbed on each surface of the basal layer of LDHs. In other words, a bilayer is formed in the gallery of LDHs.
Co-reporter:Yan Li, Wan-Guo Hou, Wei-Qun Zhu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 303(Issue 3) pp:166-172
Publication Date(Web):15 August 2007
DOI:10.1016/j.colsurfa.2007.03.042
Hydrotalcite-like compounds (HTlc) is a new large family of layered inorganic materials with positive structural charges and cationic starch (CS) is a large-scale commercial product. CS–HTlc aqueous dispersion is expected to be used in many fields such as drug delivery and the recover of oil, the adsorption of CS on HTlc may play an important role on its properties and applications. However, to the best of our knowledge, no other previous work was reported on the adsorption of CS on HTlc. In this paper, the adsorption of CS on Mg–Al HTlc was investigated. The following results were obtained. CS may be adsorbed on the external surface of positively structurally charged Mg–Al HTlc, which is an entropic driving process. The adsorption isotherms are low-affinity Langmuir type, and the adsorption kinetic shows an overshoot, which may be ascribed to the CS clustering. The addition of NaCl and AlCl3 may evidently increase the adsorption. The increases of pH and temperature may result in the increase of the adsorption.
Co-reporter:X.N. Dai, W.G. Hou, H.D. Duan, P. Ni
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 295(1–3) pp:139-145
Publication Date(Web):1 March 2007
DOI:10.1016/j.colsurfa.2006.08.043
The rheological characteristics of Mg–Al-layered double hydroxide (LDHs)/kaolinite dispersions were investigated as a function of pH and mass ratio of LDHs to kaolinite (R). The stress ramp and stress sweep experiments were used to measure the yield stress of the dispersions. In both experiments, a critical shear stress (τc) was obtained at which the viscosity decreased by 3–4 orders of magnitude. The τc value decreased first and then increased with the increase of the R, showing a minimum at R = 0.05. The linear oscillatory shear experiments and the thixotropic loops experiments were performed to investigate the thixotropic behavior of the dispersions. The complex thixotropy was observed with the linear oscillatory shear experiments, and it was found that the thixotropic type of the LDHs/kaolinite dispersions may be affected by R in the range of 0–0.35 and pH value in the range of 3–12. With the increase of R or pH value, the thixotropic type of LDHs/kaolinite dispersions transformed from positive thixotropy to complex thixotropy. By comparing the results of the thixotropic loops experiments with those of the linear oscillatory shear experiments, it was demonstrated that thixotropic loop of complex thixotropy had a crossover point that divided the loop into two sections.
Co-reporter:Wan-Guo Hou;Carolyn Ren
Chinese Journal of Chemistry 2006 Volume 24(Issue 10) pp:
Publication Date(Web):2 OCT 2006
DOI:10.1002/cjoc.200690249
The intrinsic surface reaction constants, pKinta1, pKinta2, p*KintC and p*KintA, were evaluated by a modified double extrapolation (MDE) for TiO2 without structural charge and Mg-Fe hydrotalcite-like compounds (HTlc) with structural charge, respectively. The results of intrinsic surface reaction constants for TiO2 were compared with those obtained by class double extrapolation (CDE) in literature. Furthermore, the values of intrinsic surface reaction constants obtained by MDE were used to simulate the charging behaviors of the materials. The following conclusions were obtained. For TiO2 without structural charge, the pKinta1 and pKinta2 evaluated by MDE are equal to those by CDE, however the p*KintC and p*KintA evaluated by MDE are much different from those by CDE. In principle, the results of the p*KintC and p*KintA evaluated by MDE are more accurate than those by CDE. The values of intrinsic surface reaction constants obtained by MDE can excellently simulate the charging curves for TiO2 with the triple layer model (TLM). For HTlc with positive structural charge, the results of *KintC=0 and *KintA∞ were obtained by MDE, which means the inert electrolyte chemical binding does not exist; the point of zero net charge (PZNC) of c-independence also exist as the same as solid without structural charge, and the pHPZNC obtained by the acid-base titration can excellently be simulated and the surface charging tendency can be simulated to a great extent using the pKinta1 and pKinta2 evaluated by MDE and the diffuse layer model (DLM).
Co-reporter:Wan-Guo Hou;Shu-Hua Han;Dong-Xiang Li;Gao-Yong Zhang
Chinese Journal of Chemistry 2004 Volume 22(Issue 3) pp:
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20040220311
The relationship among intrinsic surface reaction constant (K) in 1-pK model, point of zero net charge (PZNC) and structural charge density (σst) for amphoteric solid with structural charges was established in order to investigate the effect of σst on pK. The theoretical analysis based on 1-pK model indicates that the independent PZNC of electrolyte concenmtion (c) exists for amphoteric solid with structural charges. A common intersection point (CIP) should appear on the acid-base titration curves at different c. and the pH at the CIP is pHPZNC. The pK can be expressed as pK=-pHPZNC+log[(l+2αPZNC)/(1–2αPZNC)], where α-PZNC σ/eNANs, in which e is the elementary charge, Na the Avogadro's constant and NS the total density of surface sites. For solids without structural charges, pK=- pHPZNC. The pK values of hydrotalcite-like compounds (HTlc) with general formula of [Mg1-x Fex(OH)2](Cl, OH)x were evaluated. With increasing x. the pK increases, which can be explained based on the affinity of metal cations for H− or OH− and the electrostatic interaction between charging surface and H− or OH−.
Co-reporter:S.P Li, W.G Hou, J.C Xiao, J.F Hu, D.Q Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2003 Volume 224(1–3) pp:149-156
Publication Date(Web):29 August 2003
DOI:10.1016/S0927-7757(03)00262-0
The influence of the measuring conditions on the thixotropy of suspensions, which were made up of hydrotalcite-like compounds (HTlc) and Na-montmorillonite (MT), was studied. Usually, the structure recovery at rest after preshear is considered the fundamental thixotropic process. And the recovery process was performed under the steady shear experiments, then the thixotropic type can be judged according to the recovery process. In this paper, the influence of rest time (ts) and the shear rate () on the recovery process was studied. Three kinds of HTlc/MT suspension were studied, their mass ratios of HTlc to MT, which were signed as R (e.g. R=WHTlc/WMT), were 0.013, 0.051, 0.091, respectively. It is found the HTlc/MT suspension with R=0.013 showed positive thixotropy at ts=0, but it changed to negative one with the increase of ts. The suspension with R=0.051 transformed from complex thixotropy at low or positive thixotropy at high into negative one with the increase of ts. The suspension with R=0.091 behaved as complex thixotropy when is 1022 s−1, and it behaved as negative thixotropy when is 10 s−1. Whereas, the suspension transformed from negative thixotropy to the weak complex one as the increase of ts when is 170 or 341 s−1. For all the systems, the equilibrium viscosity decreased gradually with ts at the low , but the equilibrium viscosity increased with ts at high because of the memory effect. The mechanism has been discussed.
Co-reporter:Haiping Li, Tingxia Hu, Jianqiang Liu, Shue Song, Na Du, Renjie Zhang, Wanguo Hou
Applied Catalysis B: Environmental (March 2016) Volume 182() pp:431-438
Publication Date(Web):March 2016
DOI:10.1016/j.apcatb.2015.09.050
Co-reporter:Jikuan Zhao, Xiaomei Fu, Shouzhi Zhang, Wanguo Hou
Applied Clay Science (March 2011) Volume 51(Issue 4) pp:460-466
Publication Date(Web):March 2011
DOI:10.1016/j.clay.2011.01.009
Co-reporter:Fengrong Zhang, Na Du, Haiping Li, Jianqiang Liu, Wanguo Hou
Solid State Sciences (June 2014) Volume 32() pp:41-47
Publication Date(Web):1 June 2014
DOI:10.1016/j.solidstatesciences.2014.03.012
•Hydrothermal treatment was combined with a pre-milling process.•The synthesis route could be completed at low temperature.•Resulting LDHs were well-crystallized and dispersed.•Resulting LDHs have high removal efficiency for heavy metal pollutants.Mg–Al–Fe–NO3 layered double hydroxides (LDHs) with a constant Mg2+/(Al3+ + Fe3+) molar ratio but varying Al3+/Fe3+ molar ratios were successfully synthesized by a mechano-hydrothermal (MHT) method from Mg(OH)2, Al(OH)3 and Fe(NO3)3·9H2O or Mg(NO3)2·6H2O as starting materials. The resulting LDHs (MHT-LDHs) were characterized by XRD, TEM, SEM, FT-IR, and zeta potential, size distribution and specific surface area analyses. It was found that pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The MHT route is advantageous in terms of low reaction temperature compared with the conventional hydrothermal method, and the target products are of high crystallinity and good dispersion compared with the conventional mechanochemical (MC) method. The MHT-LDHs had higher specific surface area and zeta potential, and lower hydrodynamic diameter than LDHs obtained by MC method (MC-LDHs). Furthermore, the removal of Cr(VI) from aqueous solutions using the LDHs was examined, showing that the MHT-LDHs are of higher removal efficiency than MC-LDHs for the heavy metal pollutant.High crystallized and well-dispersed Mg–Al–Fe–NO3 LDHs were synthesized via mechano-hydrothermal route. The LDHs show high removal efficiency for heavy metal pollutants from aqueous solutions. Download full-size image
Co-reporter:Tianrong Zhan, Zhengwei Tan, Xia Tian, Wanguo Hou
Sensors and Actuators B: Chemical (July 2017) Volume 246() pp:638-646
Publication Date(Web):July 2017
DOI:10.1016/j.snb.2017.02.107
Co-reporter:Haiping Li, Tingxia Hu, Renjie Zhang, Jianqiang Liu, Wanguo Hou
Applied Catalysis B: Environmental (5 July 2016) Volume 188() pp:
Publication Date(Web):5 July 2016
DOI:10.1016/j.apcatb.2016.02.015
•Solid-state Z-scheme Bi2MoO6/CuO photocatalysts were prepared.•Solid-state Z-scheme Bi2MoO6/Co3O4 photocatalysts were prepared.•Solid-state Z-scheme Bi2MoO6/NiO photocatalysts were prepared.•Internal electric fields played key roles in photoactivity of these heterojunctions.Up to now, studies on solid-state Z-scheme two-component heterojunctions have hardly referred to roles of interfacial internal electric fields (IEFs). Herein, solid-state Z-scheme Bi2MoO6/MO (M = Cu, Co3/4, or Ni) heterojunction photocatalysts were simply synthesized, for the first time, with enhanced photocatalytic performance toward organic degradation. Electron microscopy images reveal that the MO homogeneously distributes on surfaces of the Bi2MoO6 hierarchical microspheres, and they close contact with distinct heterojunction interfaces. X-ray photoelectron spectra (XPS) suggest that the electron transfer occurs between the Bi2MoO6 and MO after they contact, resulting in formation of IEFs at their interfaces. Based on band gap values and valance-band XPS and ultraviolet photoelectron spectra, energy band levels of the Bi2MoO6 and MO are defined, and directions of the interfacial IEFs are determined. The IEFs play key roles for the formation of the Z-scheme Bi2MoO6/MO heterojunctions and for the photoactivity enhancement. This work provides a better insight into the formation mechanism of solid-state two-component Z-scheme heterojunctions and a significant experimental guidance for studying other similar systems.Solid-state Z-scheme Bi2MoO6/MO (M = Cu, Co3/4, or Ni) heterojunctions were fabricated with interfacial internal electric field-improved photocatalytic performance under visible light irradiation.Download full-size image
Co-reporter:Haiping Li, Tingxia Hu, Na Du, Renjie Zhang, Jianqiang Liu, Wanguo Hou
Applied Catalysis B: Environmental (15 June 2016) Volume 187() pp:
Publication Date(Web):15 June 2016
DOI:10.1016/j.apcatb.2016.01.053
•Photoactivity of BiOBr nanosheets depends on exposed facets ((0 0 1) or (0 1 0)).•Photoactivity of BiOBr nanosheets depends on nanosheet thickness.•BiOBr-(0 1 0) exhibits higher visible-light photoactivity than BiOBr-(0 0 1).•BiOBr-(0 0 1) exhibits higher photoactivity than BiOBr-(0 0 1) under low-λ light.BiOBr nanosheets with dominant exposed (0 1 0) facets exhibit higher photocatalytic activity than those with highly exposed (0 0 1) facets under illumination of light with wavelengths (λ) of ∼365 and ≥420 nm, but lower photoactivity under light with λ of 254 nm. The λ-dependent differences in photocatalytic activity result from different (0 0 1) facet exposure percentages (F(0 0 1)) and nanosheet thicknesses (H) between the two samples. Whether the difference in F(0 0 1) or that in H influences the photoactivity of the BiOBr nanosheets as a primary factor depends on incident light penetration depth which increases with the λ. This study gives a better insight into the structure-performance relationship of two-dimensional (2D) photocatalysts and will supply important direction for photocatalytic studies of 2D semiconductors.BiOBr nanosheets with dominant exposed (0 1 0) facets exhibits higher photocatalytic performance under light with λ of ≥420 nm but lower with λ of ∼254 nm than those with highly exposed (0 0 1) facets, which results from different exposed facets and thicknesses between the two nanosheets.Download high-res image (196KB)Download full-size image
Co-reporter:Tianrong Zhan, Lili Cao, Wei Sun and Wanguo Hou
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 11) pp:
Publication Date(Web):
DOI:10.1039/C1AY05454F
Co-reporter:Na Du, Ruiying Song, Xiaoyu Zhu, Wanguo Hou, Haiping Li and Renjie Zhang
Chemical Communications 2014 - vol. 50(Issue 73) pp:NaN10576-10576
Publication Date(Web):2014/05/09
DOI:10.1039/C4CC02047B
Novel vesicles formed spontaneously from the micelle solution of DTAB, a single-tailed surfactant (STS), mediated by a rough glass surface (RGS) without any additives. The obtained STS vesicles displayed good stability upon long-term storage, exposure to high temperatures, and freeze-thawing after the removal of RGS.
Co-reporter:Haiping Li, Jingyi Liu, Xuefeng Liang, Wanguo Hou and Xutang Tao
Journal of Materials Chemistry A 2014 - vol. 2(Issue 23) pp:NaN8932-8932
Publication Date(Web):2014/04/08
DOI:10.1039/C4TA00236A
BiOBr lamellas were synthesized at different reaction pH values via a hydrothermal process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and N2 sorption measurements were used to characterize the BiOBr samples. BiOBr samples have the same lamella structures and band gaps but different lamella sizes and thicknesses. Adjusting the pH of the reaction system tunes the BiOBr lamella thickness from 42 to 21 nm. The photodegradation efficiencies of the BiOBr lamellas for rhodamine B (RhB) and methylene blue (MB) in aqueous solution were examined. The degradation efficiency for RhB is much higher than that for MB. The decrease in BiOBr lamella thickness significantly enhances the photocatalytic activity for dye degradation, despite the decrease in exposed photoactive (001) facet percentage. Decreasing the lamella thickness from 42 to 21 nm yields a more than fourfold enhancement in photodegradation efficiency of BiOBr samples for RhB. The most important factor influencing the photocatalytic activity of the BiOBr samples is their lamella thickness, rather than the exposed (001) facet percentage. Thus, even for flaky semiconductors with high exposed photoactive facet contents, the influence of lamella thickness on photocatalytic activity should be preferentially considered.
Co-reporter:Haiping Li, Quanhua Deng, Jingyi Liu, Wanguo Hou, Na Du, Renjie Zhang and Xutang Tao
Catalysis Science & Technology (2011-Present) 2014 - vol. 4(Issue 4) pp:NaN1037-1037
Publication Date(Web):2014/01/15
DOI:10.1039/C3CY00940H
Bi2MoO6/Zn–Al layered double hydroxide (LDH) hierarchical heterostructures assembled from Bi2MoO6 hierarchical hollow spheres and Zn–Al LDH nanosheets were synthesized by a low-temperature hydrothermal method. X-ray diffraction, Fourier transform-infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS) confirmed the formation of the Bi2MoO6/Zn–Al LDH composites. Morphologies were characterized by scanning electron microscopy and transmission electron microscopy (TEM). XPS and high resolution TEM indicated the formation of a Bi2MoO6/Zn–Al LDH heterojunction. Increasing the LDH content from 0 to 27.0 wt.% caused the Brunauer–Emmett–Teller (BET) specific surface area of the composites to gradually increase. The photocatalytic degradation activity for Rhodamine B (RhB) under visible light irradiation exhibited a large enhancement, followed by a decrease, with increasing LDH content. The Bi2MoO6/Zn–Al LDH heterostructure composite with LDH content of 5.5 wt.% showed the highest photocatalytic activity and degraded 99% of RhB in 80 min, while Bi2MoO6 degraded less than 50%. The average photocatalytic efficiency is enhanced by more than 100%. The enhanced photocatalytic activity of the Bi2MoO6/Zn–Al LDH heterostructure photocatalyst was mainly attributed to the efficient separation of photoinduced electrons and holes. Superoxide radicals and holes were the major active species. The Bi2MoO6/Zn–Al LDH heterostructure photocatalyst exhibited excellent stability and reusability. A detailed mechanism for its enhanced photocatalytic activity was discussed in this study. This work provides an effective way to fabricate a series of Bi-based and LDH-containing heterostructure photocatalysts.
Co-reporter:Jikuan Zhao, Yanfang Xie, Wenjie Yuan, Dongxiang Li, Shufeng Liu, Bin Zheng and Wanguo Hou
Journal of Materials Chemistry A 2013 - vol. 1(Issue 9) pp:NaN1269-1269
Publication Date(Web):2013/01/08
DOI:10.1039/C2TB00389A
Hierarchical rope-like structures based on Co–Fe layered double hydroxide (LDH) nanosheets were synthesized by the coprecipitation method from a hexagonal lyotropic liquid crystal (LLC) nanoreactor, and were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and inductively coupled plasma (ICP) analyses. It was found that the rope-like LDH structures were composed of LDH nanosheets with a lateral size of about 200–400 nm and an average thickness of 4.47 nm in the form of face-to-edge interactions. The length and the diameter of the rope-like assemblies were about 3–6 μm and 150–300 nm, respectively, and their aspect ratio was as high as 20. Interestingly, the LDH rope-like assemblies were ordered to form an array with the oriented directions parallel to each other. A formation mechanism for the hierarchical LDH structures in the LLC media was proposed. In addition, the catalytic activity of the hierarchical rope-like LDH assemblies for the oxidation reaction of the typical horseradish peroxidase (HRP) substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), was examined, and results revealed that they had a higher oxidase-like catalytic activity towards the oxidization of TMB by dissolved oxygen. We expect that the hierarchical rope-like LDHs can offer the potential applications in aqueous redox catalysts, biosensors, medical diagnostics and so on.
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