Co-reporter:Donglin Zhao, Lili Chen, Mingwenchan Xu, Shaojie Feng, Yi Ding, M. Wakeel, Njud S. Alharbi, and Changlun Chen
ACS Sustainable Chemistry & Engineering November 6, 2017 Volume 5(Issue 11) pp:10290-10290
Publication Date(Web):October 3, 2017
DOI:10.1021/acssuschemeng.7b02316
Poly 3-aminopropyltriethoxysilane is a highly reactive high-molecular polymer because of the existence of abundant amino groups, which presents a strong affinity toward different metal cations. In view of this, the novel poly amino siloxane oligomer modified graphene oxide composite (PAS–GO) was fabricated by a facile cross-linking reaction and applied to capture U(VI)/Eu(III) ions from aqueous solution. The interaction mechanisms between the PAS–GO and U(VI)/Eu(III) were elaborated. The modification by NH2 increased the sorption sites and improved the sorption capacities because of the synergistic effect of chelation with U(VI)/Eu(III). X-ray photoelectron spectroscopy revealed that nitrogen groups are involved in the removal of U(VI)/Eu(III) since nitrogen atoms of amine groups provided the lone pair of electrons with U(VI)/Eu(III) species. The maximum sorption capacity of U(VI) and Eu(III) on the PAS–GO at 298 K calculated by the Langmuir isotherm model was 310.63 and 243.90 mg/g, respectively. The PAS–GO could be repeatedly used for more than five cycles with slight degradation of sorption. High sorption efficiency and excellent reusability make the PAS–GO composite an ideal candidate for the capture of U(VI)/Eu(III) from aqueous solution.Keywords: Eu(III); Graphene oxide; Sorption; U(VI);
Co-reporter:Yang Gao;Xianlong Wang;Ahmed Alsaedi;Tasawar Hayat;Ke Chen;Xiaoli Tan
ACS Sustainable Chemistry & Engineering March 6, 2017 Volume 5(Issue 3) pp:2163-2171
Publication Date(Web):January 27, 2017
DOI:10.1021/acssuschemeng.6b02317
Zirconium oxide archored onto reduced graphene oxides (ZrO2@rGO) was fabricated via a hydrothermal method and used for Re(VII) removal from aqueous solutions. Scanning electron microscopy, Fourier transferred infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy were used to characterize the as-prepared ZrO2@rGO. The results indicated that ZrO2 was successfully decorated on rGO. The maximum sorption capacity of ZrO2@rGO toward Re(VII) was 43.55 mg/g. ZrO2@rGO exhibited enhanced sorption capacity for Re(VII) in comparison with bare ZrO2 or rGO. The sorption kinetics could be described by the pseudo-second-order equation. The sorption process of Re(VII) on ZrO2@rGO was endothermic and spontaneous. X-ray photoelectron spectroscopy indicated the formation of an ionic bond of Zr–O with Re(VII). According to the density functional theory calculations, ORe–Zr bonds on the surface of the monoclinic ZrO2 plane (m-ZrO2) (111) plane and tetragonal ZrO2 (t-ZrO2) (111) plane were formed when Re(VII) sorbs. The sorption energy of Re(VII) onto the t-ZrO2 (111) plane was 3.87 eV, being higher than that of Re(VII) onto m-ZrO2 (1.26 eV).Keywords: Interaction mechanism; Re(VII); Sorption; ZrO2@rGO;
Co-reporter:Jie Li, Xuede Li, Tasawar Hayat, Ahmed Alsaedi, and Changlun Chen
ACS Sustainable Chemistry & Engineering December 4, 2017 Volume 5(Issue 12) pp:11496-11496
Publication Date(Web):October 24, 2017
DOI:10.1021/acssuschemeng.7b02720
Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency standards for antimony can be reached by using NU-1000 as an adsorbent. Additionally, the effects of coexisting anions such as As(III), As(V), PO43–, SO42–, NO3–, and F– on the antimony adsorption onto NU-1000 were also studied. Finally, the Sb adsorption mechanism of NU-1000 was studied via X-ray photon spectroscopy and attenuated total reflection infrared spectroscopy techniques to explore the important characteristics that make NU-1000 a compelling candidate for wastewater management.Keywords: Adsorption mechanism; Antimony adsorption; NU-1000; Zr-MOFs;
Co-reporter:Kairuo Zhu, Changlun Chen, Huan Xu, Yang Gao, Xiaoli Tan, Ahmed Alsaedi, and Tasawar Hayat
ACS Sustainable Chemistry & Engineering August 7, 2017 Volume 5(Issue 8) pp:6795-6795
Publication Date(Web):July 5, 2017
DOI:10.1021/acssuschemeng.7b01036
A well-defined core-double-shell structured magnetic polydopamine@zeolitic idazolate frameworks-8 (MP@ZIF-8) hydrid microsphere consisting of the core of magnetic Fe3O4 nanoparticles, the inner shell of a polydopamine layer, and the outer shell of a porous ZIF-8 nanocrystal was prepared through a facile and green approach to achieve synergistic reduction and adsorptive removal of Cr(VI). The microsphere property was characterized methodically. The batch adsorption experiments showed that the MP@ZIF-8 exhibited high efficiency in the Cr(VI) removal from aqueous solutions, affording Cr(VI) removal capacity of 136.56 mg g–1, surpassing pristine MP (92.27 mg g–1). The pseudo-second-order model fitted the Cr(VI) removal kinetics well. Cr(VI) removal on the MP@ZIF-8 relied highly on pH values. More significantly, with the reduction of nitrogen atom group on ZIF-8 and PDA, Cr(VI) was easily converted into low toxicity Cr(III) and then immobilized on the MP@ZIF-8. Thus, the hybrid microspheres provided excellent adsorptive activity in treating Cr-contaminated wastewater.Keywords: Adsorption; Cr(VI); MP@ZIF-8 hydrid microsphere; Reduction;
Co-reporter:Lili Chen, Shaojie Feng, Donglin Zhao, Shaohua Chen, Feifei Li, Changlun Chen
Journal of Colloid and Interface Science 2017 Volume 490(Volume 490) pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.jcis.2016.11.050
In this work, zero-valent iron-polyaniline-graphene aerogel composite (Fe-PANI-GA) was prepared and applied in the removal of U(VI) from aqueous solutions by batch sorption experiments. The experimental results showed that the Fe-PANI-GA composite had an excellent removal capacity for the removal of U(VI) in acidic solutions. The results also showed that the maximum removal capacity of the Fe-PANI-GA toward U(VI) was 350.47 mg/g at pH 5.5. The sorption kinetics data were well-described by pseudo-second-order. The sorption isotherms of U(VI) fitted well with Langmuir isotherm and exhibited better removal efficiency with the increase of temperature. The thermodynamic parameters (ΔG, ΔS, ΔH) indicated that the sorption of U(VI) on the Fe-PANI-GA was an endothermic and spontaneous process. Moreover, removal mechanisms were studied based on the results of XRD, FTIR and XPS. Both U(VI) sorption and partially reductive precipitation of U(VI) to U(IV) contributed to the removal of U(VI) on Fe-PANI-GA. Therefore, Fe-PANI-GA was an economic and effective material for the removal of uranium from nuclear waste in practical application.Download high-res image (202KB)Download full-size image
Co-reporter:Donglin Zhao, Qi Zhang, Han Xuan, Yan Chen, Kehua Zhang, Shaojie Feng, Ahmed Alsaedi, Tasawar Hayat, Changlun Chen
Journal of Colloid and Interface Science 2017 Volume 506(Volume 506) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.jcis.2017.07.057
In this study, a regenerable magnetic ligand material (EDTA-mGO) was fabricated by binding chelating groups (EDTA) onto Fe3O4/graphene oxide and applied to remove U(VI) from aqueous solution. The sorption experiments were investigated under different experimental conditions, such as temperature, contact time and pH. EDTA-mGO showed fast removal capacity for U(VI) (<1.5 h) with high sorption ability (277.43 mg/g). The removal mechanisms mainly attributed to the metal-binding organic ligand (EDTA) and the electrostatic attractions between U(VI) and oxygenic functional groups. In addition, the as-prepared EDTA-mGO dispersed in water could be easily collected after the sorption by the external magnetic field within 10 s. The removal of U(VI) by EDTA-mGO followed the pseudo-second-order rate better than the pseudo-first-order. The thermodynamic data indicated the endothermic and the spontaneous nature of U(VI) sorption. Furthermore, the reproducibility studies suggested that EDTA-mGO has a good reusability and a high stability.Download high-res image (125KB)Download full-size image
Co-reporter:Yubing Sun, Xiangxue Wang, Congcong Ding, Wencai Cheng, Changlun Chen, Tasawar Hayat, Ahmed Alsaedi, Jun Hu, and Xiangke Wang
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 9) pp:4608
Publication Date(Web):August 9, 2016
DOI:10.1021/acssuschemeng.6b00738
Bacteria-derived carbonaceous nanofibers (CNFs) can be directly synthesized by the pyrolysis of bacterial cellulose pellicles under N2 atmosphere. The batch adsorption experiments showed that the bacteria-derived CNFs displayed the excellent adsorption performance for radionuclides. The maximum adsorption capacities of the CNFs calculated from the Langmuir model at pH 4.5 and 293 K were 67.11 mg/g for Sr(II) and 57.47 mg/g for Cs(I). The adsorption of Cs(I) and Sr(II) on the CNFs decreased with increasing ionic strength at pH < 5.0, whereas no effect of ionic strength was observed at pH > 6.0, indicating that the outer-sphere surface complexation dominated the radionuclide adsorption at pH < 5.0 whereas the adsorption was attributed to inner-sphere surface complexation at pH > 6.0. The further evidence of surface complexation modeling indicated that Sr(II) and Cs(I) adsorption on the CNFs can be satisfactorily fitted by a double diffuse layer model with an outer-sphere (SOHSr2+/SOHCs+) and an inner-sphere complexes (SOSr+/SOCs). The X-ray photoelectron spectroscopy analyses demonstrated that the adsorption of Sr(II) and Cs(I) on the CNFs were ascribed to the combination of the oxygenated functional groups of the CNFs. These observations indicated that the CNFs, as inexpensive and available carbon-based nanomaterials, can be regarded as a promising adsorbent for the removal of radionuclides from aqueous solutions in environmental pollution cleanup.Keywords: CNFs; Modeling; Radionuclides; Removal; Spectroscopy analysis
Co-reporter:Yang Gao, Changlun Chen, Xiaoli Tan, Huan Xu, Kairuo Zhu
Journal of Colloid and Interface Science 2016 Volume 476() pp:62-70
Publication Date(Web):15 August 2016
DOI:10.1016/j.jcis.2016.05.022
Polyaniline (PANI) was modified onto 3D flower-like molybdenum disulfide (MoS2) to prepare a novel organic–inorganic hybrid material, PANI@MoS2. PANI@MoS2 was characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results indicate that PANI was modified onto MoS2. PANI@MoS2 was applied as an adsorbent to remove Cr(VI) from aqueous solutions, and the adsorption isotherms fit well to the Langmuir model; the maximum removal capacity of Cr(VI) by PANI@MoS2 was 526.3 and 623.2 mg/g at pH 3.0 and 1.5, respectively. PANI@MoS2 exhibited an enhanced removal capacity of Cr(VI) in comparison with bare MoS2 and other adsorbents. The adsorption of Cr(VI) on PANI@MoS2 might be attributed to the complexation between the amine and imine groups on the surface of PANI@MoS2 with Cr(VI). This study implies that the hybrid material PANI@MoS2 is a potential adsorbent for Cr(VI) removal from large volumes of aqueous solutions.
Co-reporter:Lili Chen, Donglin Zhao, Shaohua Chen, Xianbiao Wang, Changlun Chen
Journal of Colloid and Interface Science 2016 Volume 472() pp:99-107
Publication Date(Web):15 June 2016
DOI:10.1016/j.jcis.2016.03.044
Amino functionalized magnetic graphene oxide composite (AMGO), a good sorbent for U(VI), was fabricated and characterized. The AMGO was applied as a magnetic sorbent for the U(VI) removal from aqueous solutions. The AMGO can be easily recovered from the solution with the magnetic separation within one minute. The kinetic data were well-described by the pseudo-second-order equation. The Langmuir model fitted the sorption isotherm data better than the Freundlich model. The maximum sorption capacity of the AMGO for U(VI) was 141.2 mg/g, displaying a high efficiency for the removal of U(VI). It was found that the U(VI) sorption was accomplished mainly via chelation or ion exchange. The thermodynamic parameters illustrated that the sorption process was spontaneous and endothermic in nature. In addition, the excellent reproducibility indicate that the AMGO can be used as a potential sorbent for removal of U(VI) from large volumes of aqueous solution.
Co-reporter:Donglin Zhao, Xuan Gao, Changnian Wu, Rong Xie, Shaojie Feng, Changlun Chen
Applied Surface Science 2016 Volume 384() pp:1-9
Publication Date(Web):30 October 2016
DOI:10.1016/j.apsusc.2016.05.022
Highlights
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AMGO was synthesized through a facile one-step chemical route for adsorption of Cr(VI).
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Cr(VI) was reduced to the Cr(III) and thus improved the adsorption capacity.
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AMGO can be easily separated from aqueous solution by external magnetic field.
Co-reporter:Yang Gao, Changlun Chen, He Chen, Rui Zhang and Xiangke Wang
Dalton Transactions 2015 vol. 44(Issue 19) pp:8917-8925
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5DT01093D
The organic–inorganic hybrid material of polyaniline/titanium(IV) (PANI/Ti(HPO4)2) was synthesized by an oxidative polymerization reaction. The PANI/Ti(HPO4)2 was applied to remove Re(VII). The size of Ti(HPO4)2 nanoplates has no obvious effect on the sorption capacity. The effects of various environmental factors (such as pH, extra anions (NO3− and MO42−) and temperature) on Re(VII) sorption to PANI/Ti(HPO4)2 were investigated by batch experiments. The sorption kinetics followed a pseudo-second-order model. The nitrogen-containing functional groups of PANI promoted Re(VII) sorption. The PANI/Ti(HPO4)2 exhibited excellent maximum sorption capacity to Re(VII) (47.62 mg g−1), which was superior to that of PANI (10.75 mg g−1) and much higher than that of many other sorbents. The sorption isotherms of Re(VII) can be well fitted with the Langmuir model. Re(VII) sorption decreased with increasing solution pH at pH > 4.0, which implied that Re(VII) sorption on PANI/Ti(HPO4)2 might be attributed to the outer-sphere complexation between amine and imine groups on the surface of PANI/Ti(HPO4)2 and Re(VII). This study implies that the hybrid material of PANI/Ti(HPO4)2 can be regarded as a potential sorbent to remove Re(VII) and its analogues from large volumes of aqueous solutions.
Co-reporter:Congcong Shen, Changlun Chen, Tao Wen, Zhiwei Zhao, Xiangke Wang, Anwu Xu
Journal of Colloid and Interface Science 2015 Volume 456() pp:7-14
Publication Date(Web):15 October 2015
DOI:10.1016/j.jcis.2015.06.004
In this work, graphitic-C3N4 (g-C3N4) was synthesized by a simple and environmentally friendly salt melt method, and characterized by using field-emission scanning and transmission electron microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption–desorption analysis. The as-prepared g-C3N4 was used as an adsorbent to remove heavy metal ions from aqueous solutions. The adsorption kinetics of Pb(II) and Cu(II) followed the pseudo-second-order model. The g-C3N4 exhibited much higher adsorption capacity toward heavy metal ions (1.36 mmol/g for Pb(II), 2.09 mmol/g for Cu(II), 1.00 mmol/g for Cd(II) and 0.64 mmol/g for Ni(II)) than other adsorbents. The adsorption of Pb(II) and Cu(II) on g-C3N4 was slightly affected by ionic strength at pH < 5.0 and increased with the increase of ionic strength at pH > 5.0. The inner-sphere surface complexation mechanism was suitable to explain the interaction between heavy metal ions and the nitrogen- and carbon-containing functional groups of the g-C3N4. The experimental results reveal that g-C3N4 is a potential adsorbent for the removal of heavy metal ions from large volumes of aqueous solutions.
Co-reporter:Dr. Shubin Yang;Dr. Changlun Chen;Dr. Yue Chen;Jiaxing Li;Dr. Dongqi Wang;Dr. Xiangke Wang;Dr. Wenping Hu
ChemPlusChem 2015 Volume 80( Issue 3) pp:480-484
Publication Date(Web):
DOI:10.1002/cplu.201402284
Abstract
The individual and competitive adsorption of PbII, NiII, and SrII on graphene oxides (GOs) was investigated by experimental and density functional theory (DFT) studies. Experimental results indicate that 1) in all the single, binary, and ternary metal-ion adsorption systems, the sequence of maximum adsorption capacities is PbII>NiII>SrII on GOs; 2) the desorption hysteresis of metal ions from GOs shows the adsorption affinity in the same sequence: PbII>NiII>SrII. For the first time, DFT calculations indicate that 1) PbII and NiII prefer to interact with the COH group, whereas SrII interacts with COH and COC comparably, and 2) PbII can easily abstract the OH group from the GOs to form the much more stable Pb(OH)–GO complex. These findings are very important and useful for understanding the mechanisms of heavy-metal-ion adsorption on GOs and assessing the adsorption of coexisting heavy-metal ions on GOs.
Co-reporter:Mancheng Liu, Changlun Chen, Tao Wen and Xiangke Wang
Dalton Transactions 2014 vol. 43(Issue 19) pp:7050-7056
Publication Date(Web):24 Feb 2014
DOI:10.1039/C3DT53527D
The U(VI) magnetic ion-imprinted composite (MIIC) with a uniform core–shell structure for the selective separation and preconcentration of U(VI) was prepared by copolymerization of a ternary complex of uranyl ions with 4-vinylpyridine (4-VP) and acrylamide in the presence of 2,2′-azobisisobutyronitrile. The sorption of U(VI) on the MIIC from aqueous solution was evaluated. The maximum sorption capacity of MIIC for U(VI) was 354.85 mg g−1, which was much higher than that of the magnetic nonimprinted composite. The MIIC could be recovered by desorbing the U(VI)-loaded MIIC with 0.5 mol L−1 HNO3, and the surface morphology of MIIC after five consecutive sorption/desorption cycles was significantly damaged. The competitive sorption experiments showed that the MIIC had a desirable selectivity for U(VI) over a range of competing metal ions. The MIIC may be a promising sorbent material for the selective separation and preconcentration of U(VI).
Co-reporter:Jie Li, Zhenyi Shao, Changlun Chen and Xiangke Wang
RSC Advances 2014 vol. 4(Issue 72) pp:38192-38198
Publication Date(Web):26 Aug 2014
DOI:10.1039/C4RA05800C
Graphene oxides (GOs) decorated with Fe3O4 nanoparticles (GOs/Fe3O4) were modified by polyaniline (PANI). Selecting methyl orange (MO) as an organic pollutant model, the hierarchical GOs/Fe3O4/PANI magnetic composites showed high adsorption capacity toward MO (585.02 mg g−1), which was superior to that of other adsorbents. The nitrogen-containing functional groups of PANI decorated on GOs/Fe3O4/PANI provided numerous effective adsorption sites and thus increased the adsorption capacity for MO. Moreover, PANI protected the Fe3O4 nanoparticles from dissolution, and therefore improved the stability of GOs/Fe3O4/PANI in solution. The results show that the GOs/Fe3O4/PANI magnetic composites are promising magnetic nanomaterials for the preconcentration and separation of ionic dye pollutants from aqueous solutions for environmental pollution cleanup.
Co-reporter:Jie Li, Changlun Chen, Shouwei Zhang and Xiangke Wang
Environmental Science: Nano 2014 vol. 1(Issue 5) pp:488-495
Publication Date(Web):10 Jul 2014
DOI:10.1039/C4EN00044G
This study investigated the influence of the structure characteristics of carbon nanotubes (CNTs), such as surface oxygen-containing functional groups, specific surface area (SSA) and concentration of defects, on the adsorption–desorption hysteresis of a metal cation (Cu(II)) and two oxoanions (As(V) and Cr(VI)), from single, double and multi-walled CNTs (SWCNTs, DWCNTs and MWCNTs), and two oxidized MWCNTs with different oxygen concentrations (MWCNTs-O1, 2.51 wt% O and MWCNTs-O2, 3.5 wt% O). Oxygen-containing functional groups contributed to an increase in the adsorption capacity for Cu(II) from aqueous solutions, but a decrease in adsorption capacity for Cr(VI) and As(V). The order of adsorption capacities based on CNT SSA was MWCNTs-O2 > MWCNTs-O1 > MWCNTs > DWCNTs > SWCNTs, which was consistent with the order of CNT defect contents. Desorption hysteresis index (HI) values for Cu(II) increased as the number of functional groups increased. For Cr(VI) and As(V), however, HI values decreased as the number of functional groups increased. HI values decreased with an increase in metal ion surface coverage on CNTs. There may be a shift in the mechanisms of metal ion adsorption by CNTs, from more irreversible to more reversible processes, with an increase in adsorbed metal ions. An understanding of the desorption hysteresis of heavy metal ions is important and useful for the application and risk assessment of CNTs in the natural environment.
Co-reporter:Dr. Jie Li;Dr. Changlun Chen;Dr. Shouwei Zhang;Dr. Xuemei Ren;Dr. Xiaoli Tan ; Xiangke Wang
Chemistry – An Asian Journal 2014 Volume 9( Issue 4) pp:1144-1151
Publication Date(Web):
DOI:10.1002/asia.201301475
Abstract
Single-, double-, and multi-walled carbon nanotubes (SWCNTs, DWCNTs, and MWCNTs), and two oxidized MWCNTs with different oxygen contents (2.51 wt % and 3.5 wt %) were used to study the effect of the wall number and surface functionalization of CNTs on their adsorption capacity and adsorption–desorption hysteresis for heavy metal ions (NiII, CdII, and PbII). Metal ions adsorbed on CNTs could be desorbed by lowering the solution pH. Adsoprtion of heavy metal ions was not completely reversible when the supernatant was replaced with metal ion-free electrolyte solution. With increasing wall number and amount of surface functional groups, CNTs had more surface defects and exhibited higher adsorption capacity and higher adsorption–desorption hysteresis index (HI) values. The coverage of heavy metal ions on the surface of CNTs, solution pH, and temperature affect the metal ion adsorption–desorption hysteresis. A possible shift in the adsorption mechanism from mainly irreversible to largely reversible processes may take place, as the amount of metal ions adsorbed on CNTs increases. Heavy metal ions may be irreversibly adsorbed on defect sites.
Co-reporter:Ying Zhao, Donglin Zhao, Changlun Chen, Xiangke Wang
Journal of Colloid and Interface Science 2013 Volume 405() pp:211-217
Publication Date(Web):1 September 2013
DOI:10.1016/j.jcis.2013.05.004
•Reduced graphene oxide decorated with TiO2 nanoparticles was synthesized.•TiO2-RGO exhibited an improved photocatalytic performance in Cr(VI) reduction.•The adsorption and photocatalytic reduction of Cr(VI) decreased with increasing pH.•TiO2-RGO is a promising material for Cr(VI) photocatalytic reduction.Reduced graphene oxide decorated with TiO2 nanoparticles (TiO2-RGO) was synthesized and characterized by scanning and transmission electron microscopy, powder X-ray diffraction, ultraviolet–visible spectroscopy, photoluminescence excitation and emission spectroscopy, and X-ray photoelectron spectroscopy. Photo-reduction and removal of Cr(VI) from an aqueous solution using the material were investigated under visible light irradiation. Compared to pure TiO2, the TiO2-RGO exhibited an improved photocatalytic performance in the reduction of Cr(VI) under visible light irradiation, with a maximum removal of 86.5% vs 54.2% due to the increased light absorption intensity and wavelength range as well as the reduction in electron–hole pair recombination in TiO2 with the addition of RGO. The adsorption and photocatalytic reduction of Cr(VI) decreased with increasing pH, due to the decrease in the electrostatic attraction between anionic Cr(VI) and TiO2-RGO and the decrease in the thermodynamic driving force of Cr(VI) reduction to Cr(III).Graphical abstract
Co-reporter:Donglin Zhao, Xin Yang, Changlun Chen, Xiangke Wang
Journal of Colloid and Interface Science 2013 Volume 398() pp:234-239
Publication Date(Web):15 May 2013
DOI:10.1016/j.jcis.2013.02.017
A visible-light photocatalyst of multiwalled carbon nanotubes decorated with TiO2 nanoparticles (MWCNT/TiO2) was synthesized by a two-step method, in which TiO2 was first mounted on MWCNT surfaces by hydrolysis of tetrabutyl titanate and further crystallized into anatase nanocrystal in a vacuum furnace at 500 °C. The photocatalytic degradation of methylene blue over the ultraviolet (UV) and visible-light spectrum regions was investigated. The MWCNT/TiO2 was able to absorb a high amount of photo energy in the visible-light region, driving effectively photochemical degradation reactions. There were more OH radicals produced by the MWCNT/TiO2 (1:3) than by pure TiO2 under UV and visible-light irradiation. In the photodegradation of methylene blue, as a model reaction, a signification enhancement in the reaction rate was observed with the MWCNT/TiO2 (1:3), compared to bare TiO2 and the physical mixture of MWCNTs and TiO2. MWCNTs can improve the photocatalytic activity of TiO2 in two aspects, namely e− transportation and adsorption. This work provides new insight into the fabrication of MWCNT/TiO2 as a high performance visible-light photocatalyst and facilitates its application in photocatalytic degradation of organic compounds.Graphical abstractHighlights► A visible-light photocatalyst of MWCNT/TiO2 was synthesized. ► MWCNT/TiO2 can absorb a high amount of photo energy in the visible-light region. ► The photocatalytic degradation of organic compounds on MWCNT/TiO2 is improved. ► MWCNTs can improve the photocatalytic activity of TiO2 in two aspects, namely e− transportation and adsorption.
Co-reporter:Mancheng Liu, Tao Wen, Xilin Wu, Changlun Chen, Jun Hu, Jie Li and Xiangke Wang
Dalton Transactions 2013 vol. 42(Issue 41) pp:14710-14717
Publication Date(Web):07 Jun 2013
DOI:10.1039/C3DT50955A
A composite of porous Fe3O4 hollow microspheres/graphene oxide (Fe3O4/GO) has been fabricated through a facile self-assembly approach. Driven by the mutual electrostatic interactions, the amine-functionalized Fe3O4 microspheres prepared by a hydrothermal method and then modified by 3-aminopropyltrimethoxysilane were decorated with negatively-charged GO sheets. The Fe3O4 microspheres were hollow with porous surfaces and the surfaces were successfully modified with the amine, which was confirmed by Fourier transform infrared spectroscopy. The specific saturation magnetization of Fe3O4/GO was 37.8 emu g−1. The sorption performance of Fe3O4/GO for Cr(VI) was evaluated. The maximum sorption capacity for Cr(VI) on Fe3O4/GO was 32.33 mg g−1, which was much higher than that of Fe3O4 microspheres. The GO sheets could not only prevent agglomeration of the Fe3O4 microspheres and enable a good dispersion of these oxide microspheres, but also substantially enhance the specific surface area of the composite. The Fe3O4/GO composite may be a promising sorption material for the separation and preconcentration of heavy metal ions from aqueous solutions in environmental pollution cleanup.
Co-reporter:Jie Li, Shouwei Zhang, Changlun Chen, Guixia Zhao, Xin Yang, Jiaxing Li, and Xiangke Wang
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 9) pp:4991
Publication Date(Web):September 5, 2012
DOI:10.1021/am301358b
Graphene oxide/Fe3O4 (GO/Fe3O4) composites were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The removal of Cu(II) and a natural organic macromolecule (fulvic acid (FA)) by GO/Fe3O4 was investigated. The mutual effects of FA/Cu(II) on Cu(II) and FA sorption onto GO/Fe3O4, as well as the effect of pH, ionic strength, FA/Cu(II) concentrations, and the addition sequences of FA/Cu(II) were examined. The results indicated that Cu(II) sorption on GO/Fe3O4 were strongly dependent on pH and independent of ionic strength, indicating that the sorption was mainly dominated by inner-sphere surface complexation rather than outer-sphere surface complexation or ion exchange. The presence of FA leads to a strong increase in Cu(II) sorption at low pH and a decrease at high pH, whereas the presence of Cu(II) led to an increase in FA sorption. The adsorbed FA contributes to the modification of sorbent surface properties and partial complexation of Cu(II) with FA adsorbed. Different effects of FA/Cu(II) concentrations and addition sequences on Cu(II) and FA sorption were observed, indicating the difference in sorption mechanisms. After GO/Fe3O4 adsorbed FA, the sorption capacity for Cu(II) was enhanced at pH 5.3, and the sorption capacity for FA was also enhanced after Cu(II) sorption on GO/Fe3O4. These results are important for estimating and optimizing the removal of metal ions and organic substances by GO/Fe3O4 composites.Keywords: Cu(II); Fe3O4 nanoparticles; fulvic acid; graphene oxide; sorption; thermodynamic data;
Co-reporter:Xin Yang, Changlun Chen, Jiaxing Li, Guixia Zhao, Xuemei Ren and Xiangke Wang
RSC Advances 2012 vol. 2(Issue 23) pp:8821-8826
Publication Date(Web):26 Jul 2012
DOI:10.1039/C2RA20885G
Graphene oxide (GO) and reduced graphene oxide (RGO) were both decorated with iron oxide nanoparticles and were characterized by scanning and transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorption of Pb(II), 1-naphthol, and 1-naphthylamine, as representatives of inorganic and organic pollutants, on GO-iron oxides and RGO-iron oxides was investigated. The results showed that the GO-iron oxide material was a good adsorbent for Pb(II) but not for 1-naphthol and 1-naphthylamine due to oxygen-containing groups on the surface, whereas the RGO-iron oxide material was a good adsorbent for 1-naphthol and 1-naphthylamine but not for Pb(II). The adsorption of 1-naphthol and 1-naphthylamine on RGO-iron oxides was an endothermic and spontaneous process. Both materials can be easily separated by magnetic separation.
Co-reporter:Shubin Yang, Jun Hu, Changlun Chen, Dadong Shao, and Xiangke Wang
Environmental Science & Technology 2011 Volume 45(Issue 8) pp:3621-3627
Publication Date(Web):March 11, 2011
DOI:10.1021/es104047d
This paper examines the adsorption of Pb(II) and a natural organic macromolecular compound (humic acid, HA) on polyacrylamide (PAAM) -grafted multiwalled carbon nanotubes (denoted as MWCNTs/PAAM), prepared by an N2-plasma-induced grafting technique. The mutual effects of HA/Pb(II) on Pb(II) and HA adsorption on MWCNTs/PAAM, as well as the effects of pH, ionic strength, HA/Pb(II) concentrations, and the addition sequences of HA/Pb(II) were investigated. The results indicated that Pb(II) and HA adsorption were strongly dependent on pH and ionic strength. The presence of HA led to a strong increase in Pb(II) adsorption at low pH and a decrease at high pH, whereas the presence of Pb(II) led to an increase in HA adsorption. The adsorbed HA contributed to modification of adsorbent surface properties and partial complexation of Pb(II) with the adsorbed HA. Different effects of HA/Pb(II) concentrations and addition sequences on Pb(II) and HA adsorption were observed, indicating different adsorption mechanisms. After adsorption of HA on MWCNTs/PAAM, the adsorption capacity for Pb(II) was enhanced at pH 5.0; the adsorption capacity for HA was also enhanced after Pb(II) adsorption on MWCNTs/PAAM. These results are important for estimating and optimizing the removal of metal ions and organic substances by use of MWCNT/PAAM composites.
Co-reporter:Mancheng Liu ; Changlun Chen ; Jun Hu ; Xilin Wu ;Xiangke Wang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 51) pp:25234-25240
Publication Date(Web):November 28, 2011
DOI:10.1021/jp208575m
A magnetite/graphene oxide (M/GO) composite was synthesized via a chemical reaction with a magnetite particle size of 10–15 nm and was developed for the removal of heavy metal ions from aqueous solutions. The composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The sorption of Co(II) on the M/GO composite was carried out under various conditions, that is, contact time, sorbent content, pH, ionic strength, foreign ions, and temperature. The sorption isotherms of Co(II) on the M/GO composite could be described well by the Langmuir model. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) calculated from the temperature-dependent isotherms indicated that the sorption reaction of Co(II) on the M/GO composite was an endothermic and spontaneous process. M/GO can be separated and recovered by magnetic separation. Results show that the magnetic M/GO composite is a promising sorbent material for the preconcentration and separation of heavy metal ions from aqueous solutions.
Co-reporter:Dadong Shao ; Jun Hu ; Changlun Chen ; Guodong Sheng ; Xuemei Ren ;Xiangke Wang
The Journal of Physical Chemistry C 2010 Volume 114(Issue 49) pp:21524-21530
Publication Date(Web):November 11, 2010
DOI:10.1021/jp107492g
Aniline molecules were grafted onto multiwalled carbon nanotubes (MWCNTs) by using a plasma-induced grafting technique. The polyaniline (PANI) grafted MWCNTs (PANI/MWCNTs) were characterized by using ultraviolet−visible spectrophotometry, X-ray photoelectron spectroscopy, Raman spectroscopy, thermogravimetric analysis−differential thermal analysis, and field-emission scanning electron microscopy. The results indicated that the magnetic composite consisting of PANI/MWCNTs was synthesized. The application of PANI/MWCNTs for the removal of aniline and phenol from aqueous solutions was investigated under ambient conditions. The grafted PANI on MWCNTs contributed to the enhancement of the adsorption capacity because of the strong conjugate effect between PANI and organic pollutants. PANI/MWCNTs can be separated and recovered from aqueous solution by magnetic separation. The results show that PANI/MWCNTs are a promising magnetic material for the preconcentration and separation of organic pollutants from large volumes of aqueous solutions in environmental pollution cleanup.
Co-reporter:Xiaoli Tan, Ming Fang, Changlun Chen, Shaoming Yu, Xiangke Wang
Carbon 2008 Volume 46(Issue 13) pp:1741-1750
Publication Date(Web):November 2008
DOI:10.1016/j.carbon.2008.07.023
Batch experiments were conducted to elucidate the adsorption of a widely used anionic surfactant (sodium dodecylbenzene sulfonate (SDBS)) and nickel on multiwalled carbon nanotubes (MWCNTs). Counterion effect on the removal of SDBS and nickel by using MWCNTs was also studied. The microscopic changes of MWCNTs before and after nickel and SDBS adsorption were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray photoelectron spectroscopy (XPS) was performed to study the adsorption mechanism of nickel at a molecular level. The spectroscopic analysis indicated that the adsorption mechanism was mainly attributed to chemical interaction between nickel and the surface functional groups of MWCNTs and surface adsorbed SDBS. The adsorbed SDBS on MWCNTs could lead to the modification of the MWCNT surfaces and partial complexation of nickel with SDBS adsorbed on MWCNTs. MWCNTs are efficient material in the removal of SDBS and nickel from large volume of wastewater.
Co-reporter:Changlun Chen, Jianbo He, Di Xu, Xiaoli Tan, Xiang Zhou, Xiangke Wang
Sensors and Actuators B: Chemical 2005 Volume 107(Issue 2) pp:866-871
Publication Date(Web):29 June 2005
DOI:10.1016/j.snb.2004.12.037
A novel electrochemical sensor based on nano-Au colloid modified on Pt disk microelectrode was developed for determination of carbon monoxide (CO). The catalytic activation of nano-Au colloid modified on Pt disk microelectrode as substrate was investigated in different supporting electrolyte solutions by cyclic voltammetry and constant potential transient method. The result shows that nano-Au colloid modified on Pt disk microelectrode exhibited strong catalytic effect toward the electrochemical oxidation of CO in 0.5 mol l−1 HClO4. As compared with the bare Pt disk microelectrode, the nano-Au colloid modified on Pt disk microelectrode can greatly decrease the overpotential and obviously increase the current of CO oxidation. The current–time curve recorded under conditions of constant potential and various CO concentrations suggests that current response depends linearly on CO concentration. A linear equation I (μA) = 0.00917 (μg ml−1) + 0.151 with a correlation coefficient of 0.9938 is obtained over the concentration range 0.756 μg ml−1 at potential +800 mV relative to Ag/AgCl reference electrode. The detection limit is 0.65 μg ml−1 and the relative standard deviation is 5.3% (n = 5) at room temperature.
Co-reporter:Xiaoli Tan, Changlun Chen, Shaoming Yu, Xiangke Wang
Applied Geochemistry (September 2008) Volume 23(Issue 9) pp:
Publication Date(Web):1 September 2008
DOI:10.1016/j.apgeochem.2008.07.008
Sorption of Ni2+ on Na-rectorite as a function of contact time, temperature, pH and fulvic acid (FA)/humic acid (HA) was studied under ambient conditions. A pseudo-second-order rate equation was used to simulate the kinetic sorption. The removal of Ni2+ increased with increasing pH. The presence of FA/HA enhanced the sorption of Ni2+ at low pH values, whereas no drastic effect of FA/HA on Ni2+ uptake to rectorite was found at high pH values. The diffuse layer model (DLM) fitted the experimental data of Ni2+ sorption in the absence and presence of FA/HA very well with the aid of FITEQL 3.2. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were used to simulate the sorption isotherms of Ni2+ at different temperatures. The thermodynamic data (ΔH0, ΔS0, ΔG0) were calculated from the temperature dependent sorption isotherms and the results suggested that the sorption process of Ni2+ on rectorite was spontaneous and endothermic. The sorption and species of Ni2+ on rectorite in the presence and absence of FA/HA was also investigated and characterized by XPS. The spectroscopic analysis indicated no drastic structural changes of Na-rectorite and the sorption of Ni2+ mainly occurred on the surface and at the edge position of Na-rectorite.
Co-reporter:D.L. Zhao, S.J. Feng, C.L. Chen, S.H. Chen, D. Xu, X.K. Wang
Applied Clay Science (September 2008) Volume 41(Issues 1–2) pp:17-23
Publication Date(Web):September 2008
DOI:10.1016/j.clay.2007.09.012
Co-reporter:Ying Zhao, Zhenyi Shao, Changlun Chen, Jun Hu, Hongli Chen
Applied Clay Science (January 2014) Volume 87() pp:1-6
Publication Date(Web):January 2014
DOI:10.1016/j.clay.2013.11.021
Co-reporter:S.M. Yu, C.L. Chen, P.P. Chang, T.T. Wang, S.S. Lu, X.K. Wang
Applied Clay Science (February 2008) Volume 38(Issues 3–4) pp:219-226
Publication Date(Web):February 2008
DOI:10.1016/j.clay.2007.03.008
Co-reporter:Changlun Chen, Xiangke Wang
Applied Radiation and Isotopes (February 2007) Volume 65(Issue 2) pp:155-163
Publication Date(Web):February 2007
DOI:10.1016/j.apradiso.2006.07.003
Co-reporter:Di Xu, Changlun Chen, Xiaoli Tan, Jun Hu, Xiangke Wang
Applied Geochemistry (December 2007) Volume 22(Issue 12) pp:
Publication Date(Web):1 December 2007
DOI:10.1016/j.apgeochem.2007.08.003
The sorption of Th(IV) on Na-rectorite as a function of pH, ionic strength, temperature, soil humic acid (HA) and foreign ions was studied by using a batch technique under ambient conditions. The results indicated that the sorption of Th(IV) on Na-rectorite is strongly depended on pH, ionic strength and temperature. The presence of HA enhanced Th(IV) sorption at low pH and had no obvious effect on Th(IV) sorption at high pH. The sorption of Th(IV) decreased with increasing temperature, indicating that the sorption process of Th(IV) on rectorite was exothermic. Sodium-rectorite and HA were characterized by acid–base titration to obtain the pKa, and the constant capacitance model (CCM) modeled the sorption data very well with the aid of FITEQL 3.2. HA/Th(IV) addition sequences affected Th(IV) sorption in the ternary systems. The sorption of Th(IV) on Na-rectorite may be dominated by surface complexation, while cation exchange also contributes partly to the sorption.
Co-reporter:Jie Li, Changlun Chen, Shouwei Zhang and Xiangke Wang
Environmental Science: Nano 2014 - vol. 1(Issue 5) pp:NaN495-495
Publication Date(Web):2014/07/10
DOI:10.1039/C4EN00044G
This study investigated the influence of the structure characteristics of carbon nanotubes (CNTs), such as surface oxygen-containing functional groups, specific surface area (SSA) and concentration of defects, on the adsorption–desorption hysteresis of a metal cation (Cu(II)) and two oxoanions (As(V) and Cr(VI)), from single, double and multi-walled CNTs (SWCNTs, DWCNTs and MWCNTs), and two oxidized MWCNTs with different oxygen concentrations (MWCNTs-O1, 2.51 wt% O and MWCNTs-O2, 3.5 wt% O). Oxygen-containing functional groups contributed to an increase in the adsorption capacity for Cu(II) from aqueous solutions, but a decrease in adsorption capacity for Cr(VI) and As(V). The order of adsorption capacities based on CNT SSA was MWCNTs-O2 > MWCNTs-O1 > MWCNTs > DWCNTs > SWCNTs, which was consistent with the order of CNT defect contents. Desorption hysteresis index (HI) values for Cu(II) increased as the number of functional groups increased. For Cr(VI) and As(V), however, HI values decreased as the number of functional groups increased. HI values decreased with an increase in metal ion surface coverage on CNTs. There may be a shift in the mechanisms of metal ion adsorption by CNTs, from more irreversible to more reversible processes, with an increase in adsorbed metal ions. An understanding of the desorption hysteresis of heavy metal ions is important and useful for the application and risk assessment of CNTs in the natural environment.
Co-reporter:Mancheng Liu, Changlun Chen, Tao Wen and Xiangke Wang
Dalton Transactions 2014 - vol. 43(Issue 19) pp:NaN7056-7056
Publication Date(Web):2014/02/24
DOI:10.1039/C3DT53527D
The U(VI) magnetic ion-imprinted composite (MIIC) with a uniform core–shell structure for the selective separation and preconcentration of U(VI) was prepared by copolymerization of a ternary complex of uranyl ions with 4-vinylpyridine (4-VP) and acrylamide in the presence of 2,2′-azobisisobutyronitrile. The sorption of U(VI) on the MIIC from aqueous solution was evaluated. The maximum sorption capacity of MIIC for U(VI) was 354.85 mg g−1, which was much higher than that of the magnetic nonimprinted composite. The MIIC could be recovered by desorbing the U(VI)-loaded MIIC with 0.5 mol L−1 HNO3, and the surface morphology of MIIC after five consecutive sorption/desorption cycles was significantly damaged. The competitive sorption experiments showed that the MIIC had a desirable selectivity for U(VI) over a range of competing metal ions. The MIIC may be a promising sorbent material for the selective separation and preconcentration of U(VI).
Co-reporter:Yang Gao, Changlun Chen, He Chen, Rui Zhang and Xiangke Wang
Dalton Transactions 2015 - vol. 44(Issue 19) pp:NaN8925-8925
Publication Date(Web):2015/04/02
DOI:10.1039/C5DT01093D
The organic–inorganic hybrid material of polyaniline/titanium(IV) (PANI/Ti(HPO4)2) was synthesized by an oxidative polymerization reaction. The PANI/Ti(HPO4)2 was applied to remove Re(VII). The size of Ti(HPO4)2 nanoplates has no obvious effect on the sorption capacity. The effects of various environmental factors (such as pH, extra anions (NO3− and MO42−) and temperature) on Re(VII) sorption to PANI/Ti(HPO4)2 were investigated by batch experiments. The sorption kinetics followed a pseudo-second-order model. The nitrogen-containing functional groups of PANI promoted Re(VII) sorption. The PANI/Ti(HPO4)2 exhibited excellent maximum sorption capacity to Re(VII) (47.62 mg g−1), which was superior to that of PANI (10.75 mg g−1) and much higher than that of many other sorbents. The sorption isotherms of Re(VII) can be well fitted with the Langmuir model. Re(VII) sorption decreased with increasing solution pH at pH > 4.0, which implied that Re(VII) sorption on PANI/Ti(HPO4)2 might be attributed to the outer-sphere complexation between amine and imine groups on the surface of PANI/Ti(HPO4)2 and Re(VII). This study implies that the hybrid material of PANI/Ti(HPO4)2 can be regarded as a potential sorbent to remove Re(VII) and its analogues from large volumes of aqueous solutions.
Co-reporter:Mancheng Liu, Tao Wen, Xilin Wu, Changlun Chen, Jun Hu, Jie Li and Xiangke Wang
Dalton Transactions 2013 - vol. 42(Issue 41) pp:NaN14717-14717
Publication Date(Web):2013/06/07
DOI:10.1039/C3DT50955A
A composite of porous Fe3O4 hollow microspheres/graphene oxide (Fe3O4/GO) has been fabricated through a facile self-assembly approach. Driven by the mutual electrostatic interactions, the amine-functionalized Fe3O4 microspheres prepared by a hydrothermal method and then modified by 3-aminopropyltrimethoxysilane were decorated with negatively-charged GO sheets. The Fe3O4 microspheres were hollow with porous surfaces and the surfaces were successfully modified with the amine, which was confirmed by Fourier transform infrared spectroscopy. The specific saturation magnetization of Fe3O4/GO was 37.8 emu g−1. The sorption performance of Fe3O4/GO for Cr(VI) was evaluated. The maximum sorption capacity for Cr(VI) on Fe3O4/GO was 32.33 mg g−1, which was much higher than that of Fe3O4 microspheres. The GO sheets could not only prevent agglomeration of the Fe3O4 microspheres and enable a good dispersion of these oxide microspheres, but also substantially enhance the specific surface area of the composite. The Fe3O4/GO composite may be a promising sorption material for the separation and preconcentration of heavy metal ions from aqueous solutions in environmental pollution cleanup.
