Co-reporter:Pengwu Zheng;Tiantian Ma
Industrial & Engineering Chemistry Research October 2, 2013 Volume 52(Issue 39) pp:14201-14207
Publication Date(Web):2017-2-22
DOI:10.1021/ie402220d
A novel method was used to prepare starch-grafted graphene nanosheets (GN-starch), in which graphene oxide was reduced with hydrazine hydrate in the presence of starch. The obtained GN-starch was characterized by electron microscopy, FTIR analysis, Raman spectra, thermogravimetric analysis, and UV–visible spectra, which confirmed that starch was effectively functionalized on the surface of graphene. Also, GN-starch exhibited high solubility and stability in water. The composites were also fabricated by using GN-starch as the filler in a plasticized-starch (PS) matrix. Because of the strong interaction between starch in GN-starch and the PS matrix, GN-starch can be well dispersed in the PS matrix and improve tensile strength to 25.4 MPa at a GN-starch content of 1.774 wt % and a moisture barrier even at a very low loading (0.248 wt %) of GN-starch fillers. PS/GN-starch composites could protect against UV light, and the conductivity of the composite could reach 9.7 × 10–4 S/cm at a GN-starch content of 1.774 wt %.
Co-reporter:Rufei Zhang, Pengwu Zheng, Xiaofei Ma
Journal of Alloys and Compounds 2017 Volume 690(Volume 690) pp:
Publication Date(Web):5 January 2017
DOI:10.1016/j.jallcom.2016.08.131
•REC-Fe3O4-CTS-Au was fabricated by orderly introducing Fe3O4, chitosan and AuNP.•The hydroxyl groups of chitosan prevented the aggregate of AuNPs to improve catalytic activity.•REC-Fe3O4-CTS-Au exhibited good catalytic capacity and recycle usage to the reduction of 4-NP and MO.A novel composite was assembled by introducing magnetic Fe3O4 nanoparticles, chitosan and Au nanoparticles (AuNPs) on rectorite (REC) surfaces. The obtained REC-Fe3O4-CTS-Au composite was characterized and used as the catalyst to remove 4-nitrophenol (4-NP) and methyl orange (MO) from water in the presence of NaBH4. The large surface of REC and the abundant hydroxyl group of chitosan on REC surface could restrain the agglomeration of AuNPs. REC-Fe3O4-CTS-Au exhibited the superiority in catalytic efficiency. At the catalyst dosage of 150 mg/L, it took only 15 min for 0.2 mM 4-NP solution to reach complete reduction, and 30 min for 1.0 mM 4-NP solution. This catalyst had the higher catalytic activity for 4-NP than MO reduction. Moreover, the catalyst could be conveniently separated and recycled from the reaction mixtures using an external magnetic field, and reused for 4-NP (or MO) reduction in fourteen cycles with retaining the original 99% (or 95%) conversion efficiency. This work indicates that REC-Fe3O4-CTS-Au can be a promising catalyst for the highly efficient degradation of organic dyes.Download high-res image (179KB)Download full-size image
Co-reporter:Wang Ning, Chen Xueyan, Lu Kezhen, Zhang Xingxiang, Xiaofei Ma
Materials Letters 2017 Volume 209(Volume 209) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.matlet.2017.07.125
•Zirconium-based carbon nanofibrous mats with three-dimensional macrostructures were prepared.•It exhibited elastic, flexible and fluffy characteristics.•Nano zirconium compounds were uniformly distributed in nanofibers ascribed to the chelation interaction.Zirconium-based carbon nanofibrous mats (ZrCFs) with three-dimensional macrostructures were prepared by the carbonization of the Polyacrynitrile (PAN) nonwoven mats containing zirconium oxychloride from air jet spinning. ZrCFs exhibited the elastic, flexible and fluffy characteristics, much different from the carbon nanofibres without zirconium. Nano zirconium compounds were uniformly distributed in carbon nanofibres, ascribed to the chelation interaction between Zr+ and PAN precursor. XRD showed that the ZrO2, ZrC and ZrN structures formed in carbon nanofibres of ZrCFs, which could prevent carbon nanofibres from fusing and shrinking. When nitrogen was introduced, ZrCFs could further reduce the charge transfer resistance. The flexible ZrCFs have the potential electric application, which can also be extended to the functional textiles and catalysis.
Co-reporter:Ning Wang, Zhitao Feng, Xiaofei Ma, Pengwu Zheng
Applied Clay Science 2017 Volume 146(Volume 146) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.clay.2017.05.044
•Carbon layer with oxygen containing groups formed on REC layers.•RECC reacted with STMP to introduce phosphate ester groups.•The adsorption process of Pb2 + was investigated.•Phosphate ester groups contributed to the Pb2 + advantageous selectivity and trace Pb2 + removal.At the presence of rectorite (Rec), starch was treated with hydrothermal carbonization to fabricate carbon layer with many oxygen containing groups on the surface of Rec layer, which were further reacted with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups on Rec. The obtained RecCPN were used to remove heavy metal ions from aqueous solution. The adsorption kinetics and isotherms could be described with the pseudo- second-order model and the Langmuir model. The maximum monolayer adsorption capacities could reach 258.40 mg/g for RecCPN at pH 5 and 303 K, in which the Pb2 + adsorption processes was spontaneous. The positive values of ΔH0 indicated that the interaction of Pb2 + with phosphate ester groups was endothermic. RecCPN still exhibited the good adsorption capacity in the adsorption-desorption cycles. In addition, RecCPN showed advantageous selectivity towards Pb2 + over other metal ions (Cu2 +, Ni2 +, Co2 + and Cd2 +) and still removed above 90% Pb2 + at the initial trace Pb2 + concentration (0.5 mg/L).
Co-reporter:Xiaoxuan Li, Xuan Jin, Xiaobin Yao, Xiaofei Ma, Yong Wang
Journal of Chromatography A 2016 Volume 1467() pp:279-287
Publication Date(Web):7 October 2016
DOI:10.1016/j.chroma.2016.06.074
•Four single thioether bridged cationic CD-CSPs are fabricated by mild thiol-ene click chemistry.•p-Methylphenylcarbamoylated CD-CSP can be readily prepared by a post-synthetic carbamoylation approach with a high surface loading.•The complementarity between native and phenylcarbamoyl CD significantly broadens the separation profile of CD-CSPs.•CD-CSPs with well-defined structures afford better enantioseparation ability.The preparation and evaluation of four single thioether bridged cationic cyclodextrin (CD) chiral stationary phases (CSPs) with different spacer length, selector concentration and rim functionalities are reported. Mono-6-(1-vinyl/allyl/butenylimidazolium)-β-CDs chloride were synthesized and clicked onto thiol silica to form three novel cationic native-CD-CSPs (CSP1, CSP2 and CSP3) and a post-synthetic phenylcarbamoylation of CSP2 was performed affording CSP4. The enantioseparation ability of the as-prepared CSPs were evaluated in high performance liquid chromatography (HPLC) by separating over forty enantiomers including isoxazolines, dansyl amino acids, flavonoids, tröger’s base, 4-chromanol, bendroflumethiazide and styrene oxide. Most of the enantiomers were well resolved with the resolution (Rs) of 4NPh-OPr reaching 12.68. The effects of spacer length, selector concentration and rim functionalities on the enantioseparation were investigated. A comparison of the current CSP with a commercial column (Cyclobond I 2000) was also conducted to reveal the superiors enantioselectivity of the as-prepared CSPs.
Co-reporter:Nan Wang, Pengwu Zheng, Xiaofei Ma
Powder Technology 2016 Volume 301() pp:1-9
Publication Date(Web):November 2016
DOI:10.1016/j.powtec.2016.05.051
•CSs, OCNTs and GOs with many oxygen-containing groups were prepared.•CS2 reacted with CSs, OCNTs and GOs to obtain xanthate groups.•The effect of CS2 dosage on Pb2 + adsorption was investigated.•These modified carbon materials were competitive for Pb2 + adsorption.Carbon spheres (CSs) were prepared with hydrothermal method, and multiwall carbon nanotubes (MWCNTs) and graphites were oxidized with Hummer's method. The obtained CSs, oxidized CNTs (OCNTs) and graphene oxides (GOs) included the oxygen-containing functional groups on these zero, one and two dimensional carbon materials. Carbon disulfide (CS2) was used to react with oxygen-containing groups for the formation of xanthate groups, which could produce the chelation structure with Pb2 +. The effect of CS2 dosage on the Pb2 + adsorption kinetic and isotherm of the modified CSs, OCNTs and GOs was investigated. The kinetic adsorption fit the pseudo-second-order model and the isotherm data followed the Langmuir model well. The maximum adsorption capacities for Pb2 + were 250.0, 357.1 and 500.0 mg/g for the modified CSs, OCNTs and GOs, respectively. These CS2-modified carbon materials were competitive with other absorbents for the heavy metal ions. Although the Pb2 + adsorption decreased much with the increasing of adsorption-desorption cycle times, these carbon materials still exhibited the good Pb2 + adsorption capacity.
Co-reporter:Pengwu Zheng, Yuanyuan Du, Peter R. Chang, Xiaofei Ma
Applied Surface Science 2015 Volume 329() pp:256-261
Publication Date(Web):28 February 2015
DOI:10.1016/j.apsusc.2014.12.158
Highlights
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The amylose–HNT–TiO2 with high dispersion of TiO2 was fabricated.
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The amylose–HNT–TiO2 was characterized.
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The photodegradation of MB and 4-NP was investigated.
Co-reporter:Fei Wang, Peter R. Chang, Pengwu Zheng, Xiaofei Ma
Applied Surface Science 2015 Volume 349() pp:251-258
Publication Date(Web):15 September 2015
DOI:10.1016/j.apsusc.2015.05.013
Highlights
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The monolithic rectorite/starch composites were fabricated.
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Two modifications of the composites were treated.
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The adsorptions of MB and Pb(II) were studied.
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The adsorption/desorption cycles of the modified composites were researched.
Co-reporter:Pengwu Zheng, Yuanyuan Du, Xiaofei Ma
Materials Chemistry and Physics 2015 Volume 151() pp:14-17
Publication Date(Web):1 February 2015
DOI:10.1016/j.matchemphys.2014.11.075
•Fe3O4@HNT was prepared.•Fe3O4@HNT was characterized.•Fe3O4 particles were selectively synthesized in the lumen of HNT.As the adsorbents or the supports of photocatalysts, halloysite nanotubes (HNT) were expected to have intact external surface for adsorption or catalyst immobilization, when Fe3O4 particles was introduced to prepare magnetic HNTs for easy separation. The negatively charged urease was loaded inside positively charged HNT lumen, and urease catalyzed the hydrolysis of urea and resulted in the alkaline environment in HNT lumen. When Fe3+ and Fe2+ diffused in, Fe3O4 particles were selectively synthesized in the lumen of HNT. The obtained Fe3O4@HNT is characterized by transmission electron microscopy and Fourier transform infrared spectroscopy, X-ray diffraction and hysteresis loops. The obtained magnetic Fe3O4@HNT can be magnetically collected with intact external surface, which can support photocatalysts or remove the pollutants.
Co-reporter:Ning Wang, Peter R. Chang, Pengwu Zheng, Xiaofei Ma
Diamond and Related Materials 2015 Volume 55() pp:117-122
Publication Date(Web):May 2015
DOI:10.1016/j.diamond.2015.03.017
•CD was grafted onto CNTs.•CNT–CD can be dispersed well in water.•The electrochemical recognition of TA was researched.•The linear dependence of ΔI on CL is ΔIL = 2.00 CL-5.62•The enantiomeric ratio of L-TA in TA samples can be calculated by testing ΔI.Since β-Cyclodextrin (CD) is the chiral selector, and carbon nanotube (CNT) is a good adsorbent and a good conductor for electron transfer, CD was covalently attached on CNT during the reduction of oxidized CNT with hydrazine hydrate for electrochemical recognition of the chiral enantiomers. The obtained CNT–CD could disperse well in water because of the hydrophilic groups from CD. A modified electrode — composed of CNT–CD, methylene blue (MB), and a glassy carbon electrode (GCE), was designed for electrochemical recognition of chiral tartaric acid (TA). Since β-CD selectively holds L-TA, this stable complex inhibited electron transfer and linearly decreased the redox current of MB. The concentrations of L-TA or D-TA in aqueous solution could be estimated from the linear equation between the difference of the redox peak current (ΔI) and the concentration, and the enantiomeric ratio of L-TA in TA samples could be calculated by determining ΔI because of the linear relationship, ΔI (μA) = 0.068 × (L-TA ratio × 100%) + 8.2.
Co-reporter:Jing Cheng, Peter R. Chang, Pengwu Zheng, and Xiaofei Ma
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 4) pp:1415-1421
Publication Date(Web):January 9, 2014
DOI:10.1021/ie402658x
β-Cyclodextrin (CD) grafted carbon nanotube (CNT) composites were prepared by the reduction of oxidized CNT with hydrazine hydrate in the presence of CD. The obtained reduced CNT-CD (RCNT-CD) was attached to iron oxide particles in preparation of magnetic RCNT-CD (M-RCNT-CD). These composites were characterized by Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TG). About 17 wt % CD was grafted onto RCNT, and about 23.5 wt % iron oxide particles were attached to the RCNT-CD. The kinetic adsorption fit the pseudo-second-order model, and the isotherm data followed the Langmuir model. The maximum adsorption capacity reached 196.5 mg/g for M-RCNT-CD, indicating that it is a good adsorbent for methylene blue. The positive free energy change (ΔG°) and negative enthalpy change (ΔH°) illustrated that the adsorption process was spontaneous and endothermic. M-RCNT-CD can be easily separated from solution in the magnetic field.
Co-reporter:Tiantian Ma, Peter R. Chang, Pengwu Zheng, Feng Zhao, Xiaofei Ma
Materials Chemistry and Physics 2014 Volume 146(Issue 3) pp:446-451
Publication Date(Web):14 August 2014
DOI:10.1016/j.matchemphys.2014.03.051
•GO gels were fabricated in the simple process.•GO–SA gel was reduced to GN–SA gel by glucose.•GO–SA and GN–SA gels were characterized.•Three liquids with different polarity were adsorbed by GO–SA and GN–SA gels.•Electrochemical properties of GN–SA gel were studied.Ultra-light porous 3D network graphene oxide (GO) gels were prepared using a simple process of aqueous gel precursor freezing, solvent exchange, and ethanol drying rather than supercritical drying technology. The GO sheets were consolidated by cross-linked sodium alginate (SA) and the obtained GO–SA gel was reduced by glucose to prepare graphene nanosheet–SA (GN–SA) gel. The gels were characterized by FTIR, XRD, SEM, and nitrogen adsorption–desorption measurements. SA was proven to attach to GO or GN surfaces to form gels composed of macropores and mesopores. GO–SA gel exhibited a bulk density of 16.79 mg cm−3, and adsorbed water 17.4 times, ethanol 20.5 times, and soybean oil 22.4 times the weight of GO–SA gel, while GN–SA gel exhibited a lower bulk density of 12.93 mg cm−3, and adsorbed water 12.2 times, ethanol 16.9 times and soybean oil 32.3 times the weight of GN–SA gel. The electrochemical performance of the GN–SA gel was analyzed using cyclic voltammetry, electrochemical impedance spectrometry, and chronopotentiometry. The results revealed that GN–SA gel displayed superior capacitive performance with large capacitance (114.12 F g−1) and excellent cyclic performance.
Co-reporter:Tiantian Ma, Peter R. Chang, Pengwu Zheng, Xiaofei Ma
Carbohydrate Polymers 2013 Volume 94(Issue 1) pp:63-70
Publication Date(Web):15 April 2013
DOI:10.1016/j.carbpol.2013.01.007
The graphite was oxidized to prepare graphene oxide (GO), and GO was reduced by glucose to obtain reduced graphene oxide (RGO) sheet. There were abundant and residual oxygen-containing groups on GO and RGO, respectively. Compared to graphite, the GO and RGO sheets appeared flat and transparent, and the aqueous suspensions followed the Lambert–Beer's law well. The composites were also fabricated by using GO and RGO as the filler in plasticized-starch (PS) matrix. Because of more oxygen-containing groups, GO could form the stronger interaction with PS matrix than RGO. And GO/PS composites exhibited better tensile strength, elongation at break and moisture barrier than RGO/PS composites, but lower thermal stability. GO/PS composites could protect against UV light, while the conductivities of RGO/PS composites could reach 1.07 × 10−4, 6.92 × 10−4 and 0.01 S/cm, respectively stored at RH50, 75 and 100%.Highlights► The graphite was oxidized to obtain GO, and GO was reduced to obtain RGO sheet. ► GO and RGO were characterized. ► GO and RGO were used as the fillers of PS matrix in the casting process. ► The properties of GO/PS and RGO/PS composites were researched. ► GO endowed PS with UV shielding, and RGO endowed PS with electrical conductivity.
Co-reporter:Pengwu Zheng, Peter R. Chang, and Xiaofei Ma
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 14) pp:5066
Publication Date(Web):March 19, 2013
DOI:10.1021/ie3027372
The mineral clay rectorite (REC) was used successfully to prepare ultralight gels by the simple process of freezing the aqueous gel precursor, exchanging the solvent (ice–ethanol), and performing ethanol drying rather than employing supercritical drying technology. The light bulk density of the rectorite (REC) gel was only 18.95 mg/cm3. Three-dimensional networks in REC gels were composed of REC sheets. Cationic guar gum could intercalate into the REC layers or attach on the REC surface and consolidate the REC gel networks. This novel porous REC gel material contained many macropores and a few mesopores. The REC gel could adsorb ethanol and soybean oil as much as 5.62 and 15.8 times the weight of the gel, respectively. In addition, the adsorptions of methylene blue dye and stearic acid (phase-change material) could reach 95.24 mg/g and 39.7 g/g, respectively. REC gels thus have potential for applications in wastewater treatment and thermal energy storage.
Co-reporter:Peter R. Chang, Dayan Qian, Debbie P. Anderson, Xiaofei Ma
Carbohydrate Polymers 2012 Volume 88(Issue 2) pp:604-608
Publication Date(Web):2 April 2012
DOI:10.1016/j.carbpol.2012.01.001
Porous starch (PS) was prepared by replacing ice crystals in frozen starch gel with ethanol using a solvent exchange technique. It was then modified by succinic anhydride (SA) in a solvent/catalyst-free medium, and the obtained SA-modified PSs (SAPSs) were characterized. The degrees of substitution (DSs) of SA could be controlled by changing the SA/starch molar ratios. A high linear relationship (>0.99) between the DS and molar ratio was found. The effect of different DSs (0–1.90) on the pore size, apparent density, moisture adsorption, oil adsorption capacity and methylene blue (MB) adsorption of SAPSs was investigated. Apparent density, oil adsorption capacity and methylene blue (MB) adsorption of SAPSs increased gradually with the increasing DSs. SAPSs exhibited higher moisture content at equilibrium than PS. In addition, the adsorption of MB by SAPSs could be described well by a pseudo second-order model.Highlights► PS was prepared using a freezing-solvent exchange technique. ► The reactive PS was modified by SA in a solvent/catalyst-free medium. ► The linear relation DS = 0.0224 + 1.3099 (molar ratio). ► Effect of DS on pore structure, apparent density, moisture, oil and dye adsorption. ► The MB adsorption process fitted the pseudo second-order model.
Co-reporter:Peter R. Chang, Dongliang Wu, Debbie P. Anderson, Xiaofei Ma
Carbohydrate Polymers 2012 Volume 89(Issue 2) pp:687-693
Publication Date(Web):20 June 2012
DOI:10.1016/j.carbpol.2012.03.076
Sodium rectorite clay (REC) was attached to cationic guar gum (CGG) using a cationic-exchange reaction to obtain CGG modified-REC (CREC). It was found that CGG appeared on the surface of REC's layered structure and represented about 30.1% wt. in CREC. REC and CREC were, respectively, used as fillers in a plasticized starch (PS) matrix to prepare PS/REC and PS/CREC composites using the casting process. Rapid Visco Analyser and scanning electron microscopy revealed that an interaction existed between the REC (or CREC) filler and the matrix. Both REC and CREC had obvious reinforcing effects on the matrix. Compared to the neat matrix, REC or CREC improved the thermal stability of the composites. By increasing the filler content from 0 to 10 wt%, water vapor permeability (WVP) values of PS/REC composites obviously decreased, while WVP values of PS/CREC composites decreased slightly.Highlights► CREC was firstly prepared by modifying REC with CGG in the cationic-exchange reaction. ► REC and CREC were used as the fillers of PS matrix in the casting process. ► The interaction existed between REC (or CREC) filler and PS matrix. ► The dispersion of CREC agglomeration in the matrix was not as good as REC filler. ► REC and CREC improved thermal stability, tensile strength and water vapor barrier.
Co-reporter:Dayan Qian, Peter R. Chang, Pengwu Zheng, and Xiaofei Ma
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 23) pp:7941-7947
Publication Date(Web):May 25, 2012
DOI:10.1021/ie3001666
The carbon black-oxide (CBO) particles were prepared by oxidizing carbon black (CB) in a modified Hummer’s method to improve the dispersion of CBO in water. The carboxylic acid, epoxide groups, and hydroxyl groups were formed in the resulting golden CBO particles, which in the size of about 30–50 nm were smaller than CB particles. And the dispersion of CBO particles was so good in distilled water that CBO particles in aqueous solution followed the Lambert–Beer’s law well. The nanocomposites were also prepared using CBO or CB particles as the fillers in glycerol-plasticized starch (GPS) matrix by the casting process. CBO fillers had good dispersion in GPS matrix and exhibited an obvious reinforcing effect. Both tensile strength and Youngs modulous of GPS/CBO composites were higher than GPS/CB composites. In views of the values of water vapor permeability (WVP), GPS/CBO composites exhibited better water resistance than GPS/CB composites.
Co-reporter:Peter R. Chang, Yanfang Xie, Dongliang Wu, Xiaofei Ma
Carbohydrate Polymers 2011 Volume 84(Issue 4) pp:1426-1429
Publication Date(Web):2 April 2011
DOI:10.1016/j.carbpol.2011.01.038
Amylose was isolated from starch-rich yam, Dioscorea opposita Thunb. and used to prepare a halloysite nanotubes (HNTs) supramolecular structure by mechanical force. The thus obtained amylose wrapped halloysite nanotubes (amylose-HNTs) were characterized subsequently. Transmission electron microscopy and thermogravimetric analysis showed that the walls of the HNTs were wrapped with an amylose component (about 44.1 wt%). FTIR indicated that structural changes to amylose were related to the C–O–C groups of amylose in the interaction between amylose and the outer surface of the HNTs. Good dispersion of amylose-HNT in the DMSO/H2O solution also illustrated that an interaction existed between amylose and the HNT outer surface.
Co-reporter:Dayan Qian, Peter R. Chang, Xiaofei Ma
Carbohydrate Polymers 2011 Volume 86(Issue 3) pp:1181-1186
Publication Date(Web):30 August 2011
DOI:10.1016/j.carbpol.2011.06.012
Porous starch (PS) was created by replacing ice crystals in frozen starch gel with ethanol using a solvent exchange technique. In the single freezing process, the porous structures of PSs were controlled by changing the starch paste concentrations. With the increasing of concentrations from 5 to 20%, pore size, moisture adsorption, oil adsorption capacity and methylene blue (MB) adsorption of PSs decreased greatly, while the apparent density increased from 0.093 to 0.689 g/cm3. In the dual freezing process, the porous structures of citric acid-modified PS (CAPS0) were full of starch pastes with different concentrations (1.5, 2.5 and 3.5%), and then frozen again. Compared to CAPS0, PSs from the dual freezing process exhibited larger apparent density and MB adsorption, but lower moisture adsorption and oil adsorption capacity. And the starch paste concentrations (1.5–3.5%) had few effects on the properties of PSs in the second freezing process.Highlights► In SFP, the porous structures of PSs were controlled by changing the starch paste concentrations. ► In DFP, starch pastes were filled in the pores of citric acid modified PS from SFP, and then frozen again. ► The effects of starch concentrations on pore structure, apparent density, moisture, oil and dye adsorption were investigated.
Co-reporter:Peter R. Chang, Jiugao Yu, Xiaofei Ma, Debbie P. Anderson
Carbohydrate Polymers 2011 Volume 83(Issue 2) pp:640-644
Publication Date(Web):10 January 2011
DOI:10.1016/j.carbpol.2010.08.027
In this study, superparamagnetic Fe3O4 nanoparticles were individually prepared with one of three polysaccharides as stabilizer, i.e. soluble starch, carboxymethyl cellulose sodium (CMC) and agar. Since polysaccharides present the dynamic supramolecular associations facilitated by inter- and intra-molecular hydrogen bonding, they can act as templates for the growth of nanosized Fe3O4. The resultant polysaccharide–Fe3O4 were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetic properties. TEM revealed that Fe3O4 was encapsulated by polysaccharides. The particle size of starch–Fe3O4 (SF) was obviously smaller than those from CMC–Fe3O4 (CF) and agar–Fe3O4 (AF). TG analysis was used to calculate the Fe3O4 contents of SF, CF and AF—62.7, 47.8 and 57.4%, respectively. The saturation magnetization (20.43 emu/g) of AF was much lower than that of SF (36.16 emu/g) and CF (35.75 emu/g). The polysaccharide–Fe3O4 exhibited an extremely small hysteresis loop and low coercivity.
Co-reporter:Yanfang Xie, Peter R. Chang, Shujun Wang, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2011 Volume 83(Issue 1) pp:186-191
Publication Date(Web):1 January 2011
DOI:10.1016/j.carbpol.2010.07.039
A traditional Chinese medicine, Dioscorea opposita Thunb. is rich in starch, which was isolated and used to prepare the plasticized starch (PS). And PS was composited with halloysite nanotube (HNT) by the casting process. Amylose content of native starch was about 24.5%, and the granules were in the size of about 20 μm. The starch showed the typical B-type with relative crystallinity of 26.9%. According to the characterization of the composites with scanning electron microscope, mechanical tensile testing, rapid visco-analyser, thermogravimetric analysis and water vapor permeability, HNT could obviously improve the pasting viscosity, mechanical properties, thermal stability and water vapor barrier of the composites. When HNT contents varied from 0 to 9 wt%, the tensile strength increased from 3.9 to 9.7 MPa, and the water vapor permeability decreased from 8.48 × 10−10 to 6.61 × 10−10 g m−1 s−1 Pa−1 at RH 75% and from 14.54 × 10−10 to 11.7 × 10−10 g m−1 s−1 Pa−1 at RH 100%.
Co-reporter:Peter R. Chang, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2011 Volume 83(Issue 2) pp:1016-1019
Publication Date(Web):10 January 2011
DOI:10.1016/j.carbpol.2010.08.076
In this communication, a facile and green method is introduced for the preparation of porous starch (PS), citric acid-modified PS (CAPS) and porous ZnO. PS was created by replacing ice crystals in frozen starch gel with selected solvent using a solvent exchange technique. The porosity of PS was greatly affected by the ethanol/water volume ratios. PS was further modified with citric acid (CA) in order to preserve or maintain its porous state, especially upon contact with aqueous solution. CAPS was subsequently used as a structure-directing agent to prepare ZnO with a porous network structure. The thus obtained PS, CAPS and porous ZnO may find their niche in applications such as adsorbent, structure-directing agents for porous metal oxides or as sensors.
Co-reporter:Dongliang Wu, Peter R. Chang, Xiaofei Ma
Carbohydrate Polymers 2011 Volume 86(Issue 2) pp:877-882
Publication Date(Web):15 August 2011
DOI:10.1016/j.carbpol.2011.05.030
The Zn–Al layered double hydroxide (LDH) was fabricated using carboxymethyl-cellulose sodium (CMC) as the stabilizer in aqueous solution, and then used as the filler to prepare LDH–CMC/glycerol plasticized-starch (GPS) nanocomposites in the casting process. Transmission electron microscopy exhibited the platelets of LDH–CMC with a lateral size of 30–60 nm and the thickness of 5–10 nm. X-ray diffraction showed that the presence of CMC decreased the thickness of LDH. The chemical formulas of LDH was [Zn0.64·Al0.36·(OH)2]Cl0.36·nH2O, and the content of CMC was about 37.5 wt%. LDH–CMC possessed the good stability in water because of hydrophilic CMC components and the smaller size of each LDH stack. A low loading of LDH–CMC (below 6 wt%) could obviously improve mechanical properties and water vapor barrier of the nanocomposites, because LDH–CMC could form the good interaction with GPS matrix.Highlights► The Zn–Al LDHs were firstly prepared with CMC as the stabilizer. ► CMC exhibited the good stability of LDH in water because of hydrophilic CMC and the smaller LDH stack. ► The uniform dispersion of LDH–CMC fillers improved mechanical properties and water vapor barrier of GPS matrix.
Co-reporter:Xiaochi Ma, Peter R. Chang, Pengwu Zheng, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2010 Volume 82(Issue 1) pp:148-152
Publication Date(Web):2 August 2010
DOI:10.1016/j.carbpol.2010.04.057
Starches were isolated from three traditional Chinese medicines (TCMs), Angelica dahurica (AD), Trichosanthes kirilowii (TK) and Polygonum multiflorum (PM), which were investigated for amylose content, morphological, thermal, crystal, swelling factor, and pasting properties. Amylose contents of AD, TK and PM were 20.8%, 30.3% and 31.8%, respectively. The granule lengths were in the size of 5–30 μm, 10–22.5 μm and 8.7–18.7 μm, respectively. The decomposition temperatures were similar at about 325 °C. The AD and PM starches showed the typical B-type, while TK starch was the C-type. The degrees of crystallinity for AD, PM and TK were 38.33%, 43.10% and 36.71%. In differential scanning calorimetry analysis of starches, the transition temperatures, transition range, and enthalpies of gelatinization (ΔHgel) were determined. The pasting properties were also analyzed by using a Rapid Visco Analyzer. The dependence of swelling factor for three starches on temperature was tested at 10 °C intervals between 50 °C and 90 °C.
Co-reporter:Peter R. Chang, Ruijuan Jian, Jiugao Yu, Xiaofei Ma
Food Chemistry 2010 Volume 120(Issue 3) pp:736-740
Publication Date(Web):1 June 2010
DOI:10.1016/j.foodchem.2009.11.002
Chitosan nanoparticles (CNs), obtained by physical crosslinking between tripolyphosphate and protonised chitosan, were used as filler in a glycerol plasticised-starch (GPS) matrix to be used in food packaging. In GPS/CN composites, the chemical structures of the matrix and the filler are similar because they are both polysaccharides. The influences of the filler content on the morphology, viscosity, mechanical properties, dynamic mechanical properties, water vapour permeation and thermal degradation of GPS/CN composites were studied. It was shown that the obvious improved effect on the tensile strength, storage modulus, glass transition temperature, water vapour barrier and thermal stability could be attributed to the filler/matrix interactions, which occurred when CN was dispersed uniformly in the GPS matrix at low content. However, higher CN loads (8 wt.%) resulted in the aggregation of CN in the composites.
Co-reporter:Peter R. Chang, Ruijuan Jian, Pengwu Zheng, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2010 Volume 79(Issue 2) pp:301-305
Publication Date(Web):20 January 2010
DOI:10.1016/j.carbpol.2009.08.007
In this paper, cellulose nanoparticles (CN) were coagulated from a NaOH/urea/H2O solution of microcrystalline cellulose (MC) using an ethanol/HCl aqueous solution as the precipitant. CN ranged in size from about 50 to 100 nm. Compared to MC, CN formed a new crystalline lattice of cellulose II. The glycerol plasticized-wheat starch (GPS)/CN nanocomposites were prepared using CN as filler in GPS matrix by a casting process. At a low loading level, CN was dispersed evenly in the GPS matrix. The tensile strength increased from 3.15 to 10.98 MPa when CN content went from 0 to 5 wt.%. CN may increase the thermal stability of GPS/CN composites. Moreover, water vapor permeability decreased from 5.75 × 10−10 to 3.43 × 10−10 g m−1 s−1 Pa−1. The improvements in these properties may be attributed to the good interaction between CN filler and GPS matrix because of the similar polysaccharide structures of cellulose and starch.
Co-reporter:Jiugao Yu, Peter R. Chang, Xiaofei Ma
Carbohydrate Polymers 2010 Volume 79(Issue 2) pp:296-300
Publication Date(Web):20 January 2010
DOI:10.1016/j.carbpol.2009.08.005
Dialdehyde starch (DAS) is prepared by periodate oxidation of starch, and DAS with different aldehyde contents is plasticized by glycerol to obtain thermoplastic DAS (TPDAS). DAS is characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystalline starch is destroyed and oxidized to form amorphous DAS, while amorphous starch inside of starch granules is degraded. As a result, DAS containing 93.05% aldehyde content formes a ring shape. Compared to thermoplastic native starch, the re-crystallization of DAS can not take place in TPDAS during the storage period, because periodate oxidation has destroyed the crystallization of starch. With the increasing of aldehyde contents of DAS, the tensile strength and the resistance of both moisture absorption and water vapor permeability of TPDAS are improved. It is ascribed to the cross-linking of aldehyde groups in TPDAS.
Co-reporter:Peter R. Chang, Ruijuan Jian, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2010 Volume 80(Issue 2) pp:420-425
Publication Date(Web):12 April 2010
DOI:10.1016/j.carbpol.2009.11.041
Contrary to the most recognizable whiskers of slender parallelepiped rods, unique nanoparticles of about 50–100 nm were obtained from chitin after consecutive acid hydrolysis and mechanical ultrasonication treatments. Chitin nanoparticles (CNP) exhibited lower crystallinity when compared to conventional chitin whisker. Glycerol plasticized-potato starch (GPS) was combined with CNP to prepare all-natural nanocomposites by casting and evaporation. The morphology, structural, thermal and mechanical properties of the nanocomposites were evaluated by electron microscopy, X-ray diffraction, dynamic mechanical thermal analysis, and tensile tests. At low loading levels, CNP were uniformly dispersed in the GPS matrix and had good interaction between the filler and matrix, which led to improvements in tensile strength, storage modulus, glass transition temperature, and water vapor barrier properties of the GPS/CNP composites. However, at higher loading (greater than 5 wt.%), aggregation of CNP had a negative effect on these properties.
Co-reporter:Pengwu Zheng, Peter R. Chang, Jiugao Yu, Xiaofei Ma
Carbohydrate Polymers 2009 Volume 78(Issue 2) pp:296-301
Publication Date(Web):5 September 2009
DOI:10.1016/j.carbpol.2009.03.044
As a plasticizer of starch, 2-hydroxy-N-[2-(2-hydroxy-propionylamino)-ethyl] propionamide (HPEP) is synthesized by the reaction of lactic acid and ethylenediamine. Melt extrusion processing is used to prepare thermoplastic starch by the mixed plasticizers of formamide and HPEP (FHTPS). Fourier Transform Infrared proves that the mixed plasticizers can form the interaction with CO group of starch in FHTPS. Scanning Electron Microscope shows that formamide and original water are necessary to from the homogeneous FHTPS containing formamide/HPEP/original water (20/10/10). X-ray diffraction exhibits that the mixture of formamide and HPEP can effectively suppress starch re-crystallization, and the original water has no effect on starch re-crystallization when FHTPS are stored at RH 50% for 50 days. Water absorption testing shows that the more HPEP is, the better water resistance of FHTPS is. With the increasing of HPEP ratios, the tensile strength of FHTPS is increased while the elongation is decreased at the whole range of water contents.
Co-reporter:Peter R. Chang;Jiugao Yu
Macromolecular Materials and Engineering 2009 Volume 294( Issue 11) pp:762-767
Publication Date(Web):
DOI:10.1002/mame.200900138
Co-reporter:Xiaofei Ma, Peter R. Chang, Jiugao Yu, Peilin Lu
Carbohydrate Polymers 2008 Volume 74(Issue 4) pp:895-900
Publication Date(Web):21 November 2008
DOI:10.1016/j.carbpol.2008.05.015
As electrically conductive polymer composites, glycerol plasticized-starch (GPS)/carbon black (CB) membranes are respectively prepared by melt extrusion and microwave radiation. Scanning electron microscopy shows that the electrical conductance network of CB is formed in GPS/CB membranes, prepared by microwave radiation (GPS/CB-MR). However, the agglomerates of CB particles are isolated in GPS/CB membranes, prepared by melt extrusion (GPS/CB-ME). Fourier Transform Infrared (FTIR) spectroscopy reveals that CB and GPS matrix can form the interaction in GPS/CB membranes. According to Nicholais–Narkis models, the reinforcing effect of CB is more obvious in GPS/CB-MR membranes than in GPS/CB-ME membranes. GPS/CB-MR membranes exhibit a low electrical percolation threshold of 2.398 vol% CB loading and the conductivity of the membrane containing 4.236 vol% CB reaches 7.08 S/cm, while GPS/CB-ME membranes shows a very low conductivity of 10−8 S/cm at the high CB content. In addition, GPS/CB-MR membranes have better water vapor barrier than GPS/CB-ME membranes.
Co-reporter:Xiaofei Ma, Peter R. Chang, Jiugao Yu, Ning Wang
Carbohydrate Polymers 2008 Volume 71(Issue 2) pp:229-234
Publication Date(Web):24 January 2008
DOI:10.1016/j.carbpol.2007.05.033
The biodegradable poly(propylene carbonate) (PPC)/glycerol-plasticized thermoplastic dried starch (GPTPS) composites are prepared in a screw extruder. The dried starch is used, because the moisture in native starch easily induces the degradation of PPC during the processing. The effects of succinic anhydride (SA) on the morphology, thermal properties, dynamic mechanical thermal analysis, as well as mechanical properties of PPC/GPTPS composites, are investigated. Scanning Electron Microscope (SEM) shows that SA improves interfacial adhesion between PPC and GPTPS. Fourier Transform Infrared (FTIR) Spectroscopy reveals that SA can improve the interaction between PPC and GPTPS. Thermogravimetric Analysis (TGA) results show that SA leads a significant improvement of thermal stability for PPC/GPTPS composites. Mechanical testing illustrates that SA can increase mechanical properties of PPC/GPTPS composites. The tensile strength and elongation at break of PPC/GPTPS/SA(75/25/1) composite can reach 19.4 MPa and 88.5%, respectively.
Co-reporter:Jiugao Yu, Ning Wang and Xiaofei Ma
Biomacromolecules 2008 Volume 9(Issue 3) pp:
Publication Date(Web):February 22, 2008
DOI:10.1021/bm7012857
By using acetyl tributyl citrate (ATBC) as the plasticizer of poly(lactic acid) (PLA) and carbon black (CB) as conductive filler, electrically conductive polymer composites (CPC) with different CB and ATBC contents were prepared. FTIR revealed that the interaction existed between PLA/ATBC matrix and CB filler and ATBC could improve this interaction. The rheology showed that ATBC could obviously decrease the shear viscosity and improve the fluidity of the composites but just the reverse for CB. With the increasing of CB contents, the enforcement effect, storage modulus, and glass-transition temperature increased but the elongation at break decreased. PLA/ATBC/CB composites exhibited the low electrical percolation thresholds of 0.516, 1.20, 2.46, and 2.74 vol % CB at 30, 20, 10, and 0 wt % ATBC. The conductivity of the composite containing 3.98 vol % CB and 30 wt % ATBC reached 1.60 S/cm. Scanning electron microscopy revealed that the addition of ATBC facilitated the dispersion of the CB in the PLA matrix. Water vapor permeability (WVP) showed that, at the same CB contents, the more ATBC contents there were, the less the values of WVP were.
Co-reporter:Xiaofei Ma;Jiugao Yu;Kang He;Ning Wang
Macromolecular Materials and Engineering 2007 Volume 292(Issue 4) pp:503-510
Publication Date(Web):11 APR 2007
DOI:10.1002/mame.200600445
Plasticizers with amide groups (urea and formamide) and polyols (glycerol, glucose, and sorbitol) were used to prepare thermoplastic starch (TPS) containing NaCl salt as solid polymer electrolytes (SPE). Fourier Transform infrared (FT-IR) spectroscopy revealed that both plasticizers and Na+ could form the interaction with starch, and plasticizers containing amide groups had stronger hydrogen bond-forming abilities with starch than polyols. These interactions prevented starch molecules from crystallizing again, indicated by X-ray diffraction (XRD). Scanning electron microscope (SEM) showed that starch granules were in a molten state and a continuous phase of TPS was formed. Among TPS as SPE, formamide-plasticized TPS (FPTPS) had the largest elongation at break and lowest tensile stress. The conductance of TPS was sensitive to water. TPS plasticized by solid plasticizers had the higher sensitivity of the conductance to water contents at the low water contents (<0.1). The relationship of the conductance and water contents was in agreement with the second-order polynomial correlation when water contents were below 0.45. FPTPS had the best conductance as a whole. At the medium water content (0.2), the conductance of FPTPS containing NaCl was about 10−3 S · cm−1.
Co-reporter:Yajing Lu, Peter R. Chang, Pengwu Zheng, Xiaofei Ma
Applied Clay Science (April 2015) Volume 107() pp:21-27
Publication Date(Web):April 2015
DOI:10.1016/j.clay.2015.01.020
Co-reporter:Fei Wang, Dan Liu, Pengwu Zheng, Xiaofei Ma
Journal of Industrial and Engineering Chemistry (25 September 2016) Volume 41() pp:165-174
Publication Date(Web):25 September 2016
DOI:10.1016/j.jiec.2016.07.017
•Rectorite/Fe3O4-CTAB composite was fabricated.•Rectorite/Fe3O4-CTAB composite was characterized by XRD, FTIR, TGA, VSM, SEM, TEM and EDS mapping.•The removals of NO3− and PO43− were studied including kinetic and isotherm adsorption.•The order of Fe3O4 and CTAB introduction affected the adsorption capacity of NO3− and PO43−.The rectorite/Fe3O4-CTAB composite (REC/Fe3O4-CTAB) was fabricated by introducing cetyl trimethyl ammonium bromide (CTAB) and Fe3O4 onto the layers of raw rectorite (REC). The layers of rectorite were intercalated or exfoliated, and CTAB enhanced the electrostatic attraction by quaternary ammonium cations towards nitrate and phosphate anions. The order of Fe3O4 and CTAB introduction had great effect on the adsorption. When Fe3O4 was loaded before CTAB on REC, the obtained composites exhibited better adsorption. The maximum adsorption capacities could reach 182.1 mg/g for NO3− and 174.5 mg/g for PO43−. Besides, REC/Fe3O4-CTAB composite could be easily regenerated with NaOH solution.Download high-res image (288KB)Download full-size image
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