Co-reporter:Yuqing Zhang, Honglu Zhao
Journal of Membrane Science 2017 Volume 536(Volume 536) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.memsci.2017.04.061
•Phosphorylated ZrxSi1−xO2/Al2O3 (PZSA) particles are successfully prepared.•PZSA self-assembled membranes are formed using PZSA particles.•PZSA self-assembled membranes have a compact PZSA functional layer.•The membranes perform good separation and selective adsorption properties.•PZSA self-assembled membranes have a potential application in cleaning oily seawater.In order to deeply clean seawater containing oil, hydrolyzed polyacrylamide (HPAM) and suspended solids, phosphorylated ZrxSi1−xO2/Al2O3 (PZSA) particles were firstly prepared through co-hydrolysis, silanization and phosphorylation, followed by coating of Al2O3 and then employed as a functional layer to form PZSA self-assembled membranes on porous supports. PZSA particles were characterized by scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) while the self-assembled membranes were analyzed using SEM. Moreover, the optimum formation conditions of PZSA self-assembled membrane thickness were determined. The membranes formed under the optimal conditions were used to treat oily seawater and the quality of permeate water was investigated and analyzed. The results indicate that the particle size of PZSA is mainly distributed between 400 and 600 nm, Zr elements have been successfully doped into the lattice of SiO2 and γ-Al2O3 has been coated on the surface of ZrxSi1−xO2. Meanwhile, PZSA self-assembled membranes with desirable separation and selective adsorption properties perform attractive oil and COD retention ratio and water yield. Therefore, PZSA self-assembled membranes have the potential application in treating and cleaning oily seawater.In order to deeply clean seawater containing oil, hydrolyzed polyacryamide (HPAM) and suspended solids, phosphorylated ZrxSi1−xO2/Al2O3 (PZSA) particles were firstly prepared through co-hydrolysis, silanization and phosphorylation, followed by coating of Al2O3 and then employed as a functional layer to form PZSA self-assembled membranes on porous supports. PZSA self-assembled membranes with desirable separation and selective adsorption properties perform attractive oil retention ratio and water yield in treating oily seawater. Therefore, PZSA self-assembled membranes perform the potential application in treating and cleaning oily seawater.Download high-res image (239KB)Download full-size image
Co-reporter:Yuqing Zhang, Yufeng Zhai
Electrochimica Acta 2016 Volume 192() pp:328-339
Publication Date(Web):20 February 2016
DOI:10.1016/j.electacta.2016.01.175
To enhance the specific capacitance, cycling stability and material utilization of manganese dioxide (MnO2) for supercapacitor, MCM-41 (mesoporous silica) was firstly synthesized by hydrothermal method, and then FexSnyMn1-x-yO2 layer deposited on MCM-41 was formed through coprecipitation of MnCO3, SnCl4 and FeCl3, followed by calcination to finally obtain FexSnyMn1-x-yO2@MCM-41 electrodes (FS-MnO2@M electrodes). The structure and composition of FS-MnO2@M electrodes were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), nitrogen adsorption (BET), Fourier transform infrared spectroscopy (FT-IR) and X-Ray diffraction spectroscopy (XRD). These results of characterization about FS-MnO2@M particles show FS-MnO2 coatings are successfully deposited on the surface of MCM-41and the average coating thickness of FS-MnO2 is around 50 nm. The electrochemical performances of FS-MnO2@M electrodes are evaluated and researched by galvanostatic charge-discharge test, cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). The results show that FS-MnO2@M electrodes with porous structure display superior cycling stability at large current work condition in charge-discharge tests and good capacitance performance at high scanning rate in CV tests and FS-MnO2@M electrodes indicate the smaller internal resistance through EIS. And the specific capacitance of FS-MnO2@M reaches 319 F g−1 at current density of 2 A g−1 with the value remaining 88.37% after 10000 cycles. Therefore, the FS-MnO2@M electrode is desirable to become a novel MnO2 electrode for electrochemical supercapacitor.
Co-reporter:Yuqing Zhang and Yufeng Zhai
RSC Advances 2016 vol. 6(Issue 3) pp:1750-1759
Publication Date(Web):16 Dec 2015
DOI:10.1039/C5RA20543C
To enhance the cycling stability and conductivity of manganese dioxide (MnO2) electrodes for supercapacitors, yttrium (Y) doped zirconia (ZrO2) (denoted as Y/ZrO2) is coated on MnO2 supercapacitor electrodes (Y/ZrO2@MnO2 electrodes), so protecting the MnO2 electrodes in the electrolytes and enhancing the electrochemical performance of MnO2 electrodes in sodium sulfate electrolytes. The Y/ZrO2@MnO2 electrodes are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and XRD analysis. The electrochemical properties of the electrodes are tested and analyzed by galvanostatic charge/discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The Y/ZrO2@MnO2 electrodes achieve a specific capacity of 282.1 F g−1 with a specific capacity loss of only 6.3% after 100 cycles at the current density of 50 mA g−1. The results show that MnO2 particles are successfully deposited by Y-doped ZrO2 while the Y/ZrO2@MnO2 electrodes display better cycling stability and capacity performance. Therefore, this Y-doped ZrO2 coating is a potential choice to improve the cycling stability and conductivity of MnO2 electrodes.
Co-reporter:Yuqing Zhang and Pinjing Li
RSC Advances 2015 vol. 5(Issue 119) pp:98118-98129
Publication Date(Web):11 Nov 2015
DOI:10.1039/C5RA16319F
In order to enhance mass transfer based on immobilizing and recycling TiO2 in the process of photocatalysis, photocatalytic membranes (EC-ZSTP membranes) were prepared by embedding porous Zr-doped SiO2 shell/TiO2 core particles with expanded channels (EC-ZSTs) into polyvinylidene fluoride (PVDF). EC-ZSTs were characterized by TEM, BET, EDX and FT-IR while EC-ZSTP membranes were characterized by SEM. The preparation conditions and recycling of EC-ZSTP membranes were investigated and determined. The photocatalytic activities of EC-ZSTs and EC-ZSTP membranes were studied by the photodegradation of methyl orange solution and oil in wastewater containing oil, respectively. The results show that EC-ZSTs present better photocatalytic properties compared with the particles without expanded channels. In addition, EC-ZSTP membranes also have a better degradation rate due to improved mass transfer. Therefore, EC-ZSTP membranes will possess promising applications in the immobilization and recycling of TiO2 with better photacatalytic performance for cleaning wastewater.
Co-reporter:Yuqing Zhang, Yan Mo
Electrochimica Acta 2014 Volume 142() pp:76-83
Publication Date(Web):1 October 2014
DOI:10.1016/j.electacta.2014.07.097
•Sb-doped SnO2 coated MnO2 electrodes (SS-MnO2 electrodes) are prepared.•The capacitive property and stability of SS-MnO2 electrode is superior to uncoated MnO2 electrode and SnO2 coated MnO2 electrode.•Sb-doped SnO2 coating enhances electrochemical performance of MnO2 effectively.•SS-MnO2 electrodes are desirable to become a novel electrode material for supercapacitor.To enhance the specific capacity and cycling stability of manganese binoxide (MnO2) for supercapacitor, antimony (Sb) doped tin dioxide (SnO2) is coated on MnO2 through a sol-gel method to prepare MnO2 electrodes, enhancing the electrochemical performance of MnO2 electrode in sodium sulfate electrolytes. The structure and composition of SS-MnO2 electrode are characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-Ray diffraction spectroscopy (XRD). The electrochemical performances are evaluated and researched by galvanostatic charge-discharge test, cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). The results show that SS-MnO2 electrodes hold porous structure, displaying superior cycling stability at large current work condition in charge-discharge tests and good capacity performance at high scanning rate in CV tests. The results of EIS show that SS-MnO2 electrodes have small internal resistance. Therefore, the electrochemical performances of MnO2 electrodes are enhanced effectively by Sb-doped SnO2 coating.
Co-reporter:Yuqing Zhang, Guodong Zhang, Tingdong Du
Electrochimica Acta 2011 Volume 56(Issue 3) pp:1159-1163
Publication Date(Web):1 January 2011
DOI:10.1016/j.electacta.2010.10.027
To improve the stability of potassium ferrate(VI) (K2FeO4) cathode and its properties of charge transfer in alkaline battery system, K2FeO4 cathodes are coated by yttria (Y2O3) doped zirconia (ZrO2) composites, denoted as Y2O3–ZrO2 composite coatings. These composite coatings are derived from the conversion of yttrium nitrate (Y(NO3)3·6H2O) and Zirconium oxychloride (ZrOCl2·6H2O) in ether medium. Examinations by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) show that K2FeO4 cathodes are coated by Y2O3–ZrO2 overlayer. Alternatively, results of discharge properties and electrochemical impedance spectroscopes (EIS) indicate that when the molar ratio between Y2O3 and ZrO2 is 0.09, denoted as Y2O3 (9 mol%)–ZrO2, the stability and charge transfer of Y2O3 (9 mol%)–ZrO2 coated K2FeO4 cathodes are improved greatly compared to that of uncoated or ZrO2 coated K2FeO4 cathodes. Therefore, Y2O3–ZrO2 composite coatings are a potential choice to improve the stability and charge transfer of K2FeO4 cathodes in alkaline electrolyte.
Co-reporter:Yuqing Zhang, Xing Shan, Xiaoquan Gao
Separation and Purification Technology 2011 Volume 76(Issue 3) pp:337-344
Publication Date(Web):14 January 2011
DOI:10.1016/j.seppur.2010.10.024
The separation behavior of molecularly imprinted membrane (MIM) for flavonoids was investigated. The molecularly imprinted materials were prepared using luteolin as the template molecule and aminopropyltriethoxysilane (APTES) as the functional monomer, followed by dispersing into polysulfone (PSF) to form the MIM. The flux and the separation properties of the MIM were tested, and the Scatchard equation was used to analyze the chemical binding properties of the MIM. Experiments at different temperature were carried out and the corresponding thermodynamic parameters of separation processes in the MIM were acquired using Van’t Hoff equation. The results obtained using the Scatchard equation showed many chemical binding sites with functional groups inside the MIM's cavities. Further details of the separation processes of the MIM for flavonoids can be determined by investigating the type of pore channels in the MIM and the structure of template molecules.Graphical abstractResearch highlights▶ The MIM has some high selective channels. ▶ The MIM has excellent selective properties for separating luteolin. ▶ The equilibrium binging capacity of MIM for luteolin is larger than that for rutin.
Co-reporter:Yuqing Zhang;Yuefeng Zhang;Linru Tang
Journal of Chemical Technology and Biotechnology 2011 Volume 86( Issue 1) pp:115-120
Publication Date(Web):
DOI:10.1002/jctb.2490
Abstract
BACKGROUND: Lignocellulose is a large source of biomass. However, the conversion ratio of lignocellulose into fermentable sugars is quite low, and the saccharification process requires lots of enzyme. In order to improve biocatalysis efficiency of cellulase for lignocellulose, poly ethylene glycol (PEG4000) is added to the above process. The effect of the order of addition of PEG4000 and cellulase on lignocellulose saccharification processes, and the interaction between PEG4000 and eocellobiohydrolase I (CBH I) were investigated by DNS, UV absorption spectra and Fourier transform infrared (FTIR) spectroscopy.
RESULTS: Results show that different orders of addition of PEG4000 and cellulase have a strong influence on the saccharification process, and both orders of addition can improve the saccharification rate. In particular, the addition of PEG4000 before cellulase can reduce wasteful cellulase adsorption on the lignin, and the saccharification rate of lignocellulose can be significantly improved. Without corn stover (substrate) in the saccharification process, examinations by UV absorption spectra and FTIR demonstrate that the interactions between PEG4000 and CBH I are hydrogen bonds and hydrophobic interaction. In addition, it is found that the activity of CBH I is decreased with increasing interaction time and the amount of the PEG4000 added in the saccharification process.
CONCLUSION: The addition of PEG4000 before cellulase to lignocellulose saccharification processes is a reasonable way to improve the saccharification rate of lignocellulose. Copyright © 2010 Society of Chemical Industry
Co-reporter:Y. Zhang;C. Zhang;Y. Zhang;G. Zhang;S. Liu;Z. Xu
Chemical Engineering & Technology 2011 Volume 34( Issue 12) pp:2016-2021
Publication Date(Web):
DOI:10.1002/ceat.201100307
Abstract
To efficiently treat anionic polyacrylamide (APAM) with a linear structure in wastewater, an Al2O3 film on the surface of diatomite was prepared via the hydrolysis reaction of AlCl3. The Al2O3-coated diatomite was characterized by FT-IR, XRD, and SEM. The results show that the Al2O3 film can be coated on diatomite. The resulting Al2O3-coated diatomite was utilized to treat wastewater (pH = 7) that contained APAM of 60 mg L–1 and suspended solids of 90 mg L–1. Results show that after wastewater was treated using Al2O3-coated diatomite, the content of APAM and suspended solids in the filtrate can meet the standard for wastewater recycling. Therefore, Al2O3-coated diatomite can be used in treating wastewater containing APAM.
Co-reporter:Yuqing Zhang;Xuemin Xu;Yuyuan Zhang
Biotechnology and Bioprocess Engineering 2011 Volume 16( Issue 5) pp:
Publication Date(Web):2011 October
DOI:10.1007/s12257-011-0138-z
Fuel ethanol is one of the most important alternative fuels used as a substitute for fossil fuel. Lignocellulose is the most abundant biomass resource for the production of fuel ethanol. However, the hydrolysis of lignocellulose requires high enzyme loading. In order to strengthen the process of enzyme hydrolysis of lignocellulose, surfactant-polyethylene glycol (PEG) was applied to the catalysis of lignocellulose into fermentable sugars. The effect of PEG on both the enzymatic hydrolysis and adsorption of cellulose were investigated. The addition of surfactant obviously facilitated enzymatic hydrolysis. In particular, upon addition of PEG4000, the enzyme catalytic efficiency increased by 51.06%. Meanwhile, the adsorption quantity of cellulase decreased by 11.25%. In addition, the mechanism of the effect of PEG on enzymatic hydrolysis and cellulase adsorption is discussed.
Co-reporter:Yuqing Zhang, Zhenhua Jin, Yueling Wang, Ping Cui
Journal of Membrane Science 2010 Volume 361(1–2) pp:113-119
Publication Date(Web):30 September 2010
DOI:10.1016/j.memsci.2010.06.002
Polysulfone (PSF) membranes are broadly applied in the field of the treatment for wastewater containing oil owing to their good physicochemical stability, resistance to oxidation and chlorine. But they are easy to be contaminated by oil for its hydrophobic property, which limits their application in large scale. To enhance the capability of PSF membrane, such as hydrophilic property, anti-fouling ability and tensile strength, phosphorylated Zr-doped hybrid silica particles (SZP particles) were added to the porous matrix of PSF and a novel composite membrane (SZP/PSF) was prepared through a sol–gel process under optimum preparation conditions. The results of tensile strength and contact angle measurements show that the mechanical strength and hydrophilic property of composite membrane have been enhanced to a large extent respectively. SEM micrographs indicate that composite membrane with the asymmetry structure has both layers of compact layer and porous layer with SZP particles uniformly dispersed in PSF. The result shows that the oil concentration of 0.84 mg/L in permeation meets the standard for wastewater reuse (less than 10 mg/L). It can be concluded that the anti-fouling ability and hydrophilic property of composite membrane are significantly enhanced, and therefore, the novel composite membrane is desirable in the treatment of wastewater containing oil.
Co-reporter:Yuqing Zhang, Xiaoquan Gao, Ling Xiang, Yahui Zhang, João C. Diniz da Costa
Journal of Membrane Science 2010 Volume 346(Issue 2) pp:318-326
Publication Date(Web):15 January 2010
DOI:10.1016/j.memsci.2009.09.053
Flavonoids are natural products having several biological and physiological properties depending upon their molecular configurations. Flavonoids with similar configuration cannot be separated by traditional separation method and membrane separation technology whose selectivity is lower. This work investigates composite membranes with structural and functional molecular recognition properties prepared according to molecular imprinted technology. Functional silica sol was synthesized by taking luteolin as the template (or imprinting) molecule, γ-aminopropyltriethoxysilane (γ-APTS) as the functional monomer, and tetraethoxysilane (TEOS) as the cross-linker. The resultant functional silica sol was coated on Al2O3 microporous substrate followed by the removal of the template molecule. Scanning electron microscope micrographs showed a 5 μm thickness composite membrane with uniformly distributed porosity. Steady state flux was reached at ∼70 min at 215 L m−2 h−1 for the composite membrane, while a lower value of 168 L m−2 h−1 was measured for the blank membrane (i.e. non-templated). Further, in an aqueous mixture containing similar template molecules, the selectivity factor of luteolin to rutin was 14.1, thus suggesting that the imprinting process allowed for preferential permeance and affinity selectivity to the template molecule (i.e. luteolin). These results strongly suggest the formation of cavities, which are joined by channels to deliver the percolative effect for the permeation of luteolin. In addition to structural formation, further site recognition properties were accomplished by the functional silica sol in the composite matrix by electrovalent bonds. Considering the percolative effect in tandem with electrovalent bonds and under the influence of a concentration gradient (i.e. driving force), a mechanism of molecular recognition was proposed based on the molecular bond, followed by bond cutting and jumping to another site to form another molecular bond. The preparation method of the composite membrane was applied to other template molecules, and the template molecules can selectively permeate the membrane. So the method was universal for other substance. So it made it possible for the separation of the natural products exactly and efficiently. At the same time, it had great potential for the resolution of the chiral drugs and the preparation of the new membrane reactor.
Co-reporter:Yuqing Zhang, Guodong Zhang, Tingdong Du, Lizao Zhang
Electrochimica Acta 2010 Volume 55(Issue 20) pp:5793-5797
Publication Date(Web):1 August 2010
DOI:10.1016/j.electacta.2010.05.022
To improve the tensile strength and ionic conductivity of composite polymer films for lithium-ion batteries, molecular sieves of MCM-41 modified with sulfated zirconia (SO42−/ZrO2, SZ), denoted as MCM-41/SZ, were doped into a poly(vinylidene fluoride) (PVdF) matrix to fabricate MCM-41/SZ composite polymer films, denoted as MCM-41/SZ films. Examination by transmission electron microscope (TEM) shows that modified molecular sieves have lower aggregation and a more porous structure. Tensile strength tests were carried out to investigate the mechanical performance of MCM-41/SZ films, and then the electrochemical performance of batteries with MCM-41/SZ films as separators was tested. The results show that the tensile strength (σt) of MCM-41/SZ film was up to 7.8 MPa; the ionic conductivity of MCM-41/SZ film was close to 10−3 S cm−1 at room temperature; and the coulombic efficiency of the assembled lithium-ion battery was 92% at the first cycle and reached as high as 99.99% after the 20th cycle. Meanwhile, the charge–discharge voltage plateau of the lithium-ion battery presented a stable state. Therefore, MCM-41/SZ films are a good choice as separators for lithium-ion batteries due to their high tensile strength and ionic conductivity.
Co-reporter:Y. Zhang;T. Du;X. An;Z. Tu;G. Zhang
Chemical Engineering & Technology 2010 Volume 33( Issue 4) pp:676-681
Publication Date(Web):
DOI:10.1002/ceat.200900529
Abstract
Using the sol-gel method a series of nonstoichiometric nanosilica doped with the rare earth element Ce (CexSi1–xO2–δ, x = 0.0–0.14) were prepared in order to modify the physicochemical properties of the nanosilica surface and to enhance the strength of the Ce-nanosilica/polysulfone composite membranes. The CexSi1–xO2–δ samples were characterized by Fourier transform infrared spectra, X-ray diffraction and X-ray photoelectron spectra. The observations from these characterizations suggest that most Ce atoms enter the silica framework to form a Ce-O-Si solid solution while the cubic CeO2 phase is segregated when x >0.08. Transmission electron microscopy images show that CexSi1–xO2–δ particles are spherical with a uniform size distribution in the range of 30–50 nm and contain some inner pores with sizes up to a few nanometers. Specifically, Ce0.08Si0.92O2–δ-700 calcined at 700 °C shows the biggest surface area, the smallest pore size and the highest hydrophilicity, which makes the Ce0.08Si0.92O2–δ/polysulfone composite membranes (8.0 wt %) exhibit the strongest mechanical strength (3.223 MPa), which is enhanced by more than 100% in comparison with the pure polymer membrane.
Co-reporter:Yuqing Zhang, Xiaoquan Gao, Yueling Wang, Yahui Zhang, Gao Qing Lu
Journal of Membrane Science 2009 Volume 339(1–2) pp:100-108
Publication Date(Web):1 September 2009
DOI:10.1016/j.memsci.2009.04.035
A new accurate separate membrane (ASM) for highly specific binding and permeation of luteolin molecules from aqueous solutions has been developed by a molecular imprinting technique. Luteolin molecular imprinted materials were prepared with luteolin modified by acryloyl chloride as the template molecule, followed by dispersing into polysulfone (PSF) to form the ASM with continuous and highly selective pore channels by a phase inversion method. Thus prepared ASM was characterized and evaluated by scanning electron microscope (SEM), attenuated total reflectance infrared (ATR-FTIR) spectroscopy technique, and binding experiments. The results showed that continuous distributed pore channels matching with the template molecules in size and structure were present in the ASM. The selective binding amount reached at 28.6 mg/g for the ASM, while a lower value of 3.67 mg/g for the blank membrane (i.e. non-templated). Relative to the corresponding blank membrane, ASM had an excellent recognition to luteolin in aqueous solution. The permeation flux of ASM increased with the increase in the amount of the molecular imprinted materials. Separation of an aqueous mixture containing similar molecules (luteolin and rutin) indicated that the separation factor of luteolin and rutin is as high as 10.78. It is concluded that the molecular imprinting allowed for preferential permeance and high selectivity to the template molecule (i.e. luteolin). The results also showed the formation of pore channels created by interparticle cavities in the molecular imprinted materials. The size and structure of the channels matched well with luteolin molecules while the recognition functional groups in the pore channels of the ASM could selectively bond with the luteolin molecules by multi-hydrogen bonds. It is believed that bond cleavage and molecular hopping to another bonding site were involved in this separation process.
Co-reporter:Yuqing Zhang, Ping Cui, Tingdong Du, Libo Shan, Yueling Wang
Separation and Purification Technology 2009 Volume 70(Issue 2) pp:153-159
Publication Date(Web):10 December 2009
DOI:10.1016/j.seppur.2009.09.010
Polysulfone (PSF) is a kind of popular membrane material for treatment of wastewater containing oil, for it is easily fabricated into ultrafiltration membrane or composite membrane. When treated with wastewater, it has a tendency to be contaminated for its hydrophobicity. In order to enhance the hydrophilic and anti-fouling property of membrane, we added sulfated Y-doped nonstoichiometric zirconia (SO42−/ZrO2–Y2O3; SZY particles) to polysulfone and prepared a novel organic–inorganic composite membrane (SZY/PSF) by a sol–gel process. The optimum preparation conditions of composite membranes were: the ratio of solid (polysulfone and SZY particles), solvent and porogen (polyethylene glycol 400) was 1(g):5(mL):0.8(mL); the mass ratio of SZY particles to polysulfone was 15%; the evaporating time was 10 s and the coagulation bath temperature was 20 °C; intermittent ultrasound was on during the preparation process. Composite membranes were characterized by test of tensile strength, contact angel, porosity and pore diameter and scanning electron microscope (SEM). The results show that composite membrane is difficult to be compacted and approaches twice tensile strength of pure polysulfone membrane; contact angel reduces from 78.1° to 36.6°. SEM micrographs indicate that composite membrane owning the asymmetry structure has two layers of compact layer and porous layer with SZY particles uniformly dispersed in PSF. Wastewater containing oil (80 mg/L) was used to investigate the separation performance of composite membrane. The results reveal that oil retention is 99.16% and oil concentration in the permeation is 0.67 mg/L, which meet the requirement for discharge (<10 mg/L). It can be concluded that the composite membranes developed in the study are reasonably resistant to fouling and hence the developed PSF membranes are considered feasible in treating wastewater containing oil.
Co-reporter:Yuqing Zhang, Ling Xiang, Yahui Zhang, Xiaoquan Gao
Separation and Purification Technology 2009 Volume 65(Issue 2) pp:130-136
Publication Date(Web):23 February 2009
DOI:10.1016/j.seppur.2008.10.049
To enhance the selectivity of separation membrane in complex system, a composite membrane with molecule recognizing property is prepared according to the molecular imprinted technology. Firstly, functional silica sol was prepared by taking the luteolin as the template molecule, the γ-aminopropyltriethoxysilane (γ-APTS) as the functional monomer and the tetraethoxysilane (TEOS) as the cross-linker, and then the composite membrane was prepared through coating and grafting on the upper-side of the Al2O3 microporous membrane by using functional silica sol and removing of the template molecule. The composite membranes were examined by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), and otherwise. Meanwhile, the results showed that the functional silica gel film connected with the Al2O3 microporous membrane through chemical bond, and it had high selectivity for template molecule. The amounts of equilibrium binding are 1.87 mmol/g and 0.21 mmol/g for luteolin and rutin, respectively by binding analysis. Relative to corresponding blank membrane, the composite membrane had a more excellent recognition to luteolin in aqueous solution. The permeation and selectivity analysis showed that the selective separation of template was accomplished by using composite membrane from mixture aqueous solution containing rutin and luteolin. Evidence of the separation of the mixture indicated that the separation factor of luteolin and rutin was estimated as 14.12. The selective permeance mechanism was studied.
Co-reporter:Y. Zhang;L. Xiang;T. Du;Y. Zhang;M. Lu
Chemical Engineering & Technology 2009 Volume 32( Issue 10) pp:1512-1519
Publication Date(Web):
DOI:10.1002/ceat.200900134
Abstract
In order to selectively separate luteolin from its crude solution, we synthesized imprinted porous materials with high recognition specificity for luteolin, using an imprinting technique. Modified luteolin was used as template, vinyltriethoxysilane as the functional monomer, and tetraethyl orthosilicate (TEOS) as the cross-linking agent. The results showed the following optimum reaction conditions: The reaction ratio between luteolin and acryloyl chloride was 1 : 2 (0.10 g/0.20 g), adding 1.0 g precursor; the feasible elution time was 12 h; when the molar quantity of modified template molecule was 0.01 mol and ethenyltriethyloxy-silane (VTEO) was 0.04 mol, the maximum yield reached 91.6 %. All samples were tested by Brunauer-Emmett-Teller method, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy, equilibrium adsorption experiments and selective adsorption experiments. It was found that the imprinted porous materials showed excellent selectivity for luteolin in aqueous solution. Characterization by FTIR suggested that an addition reaction had occurred between the modified template molecule and VTEO while forming ester bonds in the functional precursor. Results from pore structure analysis indicated that the imprinted porous materials had good channels, and the average pore size of the prepared porous materials was between 35.85 and 95.82 Å. Adsorption dynamics analysis suggested that, when the adsorption time reached 3 h, the adsorption process had reached balance and the adsorption capacity was at steady state. These porous materials had highly selective recognition properties and high equilibrium adsorption capacity for the template molecule. The equilibrium adsorption capacity of the imprinted porous materials to the template molecule was 11.4 times that of the blank porous materials.
Co-reporter:Yuqing Zhang, Libo Shan, Zhengyu Tu, Yahui Zhang
Separation and Purification Technology 2008 Volume 63(Issue 1) pp:207-212
Publication Date(Web):1 October 2008
DOI:10.1016/j.seppur.2008.05.015
Polysulfone (PSF) is a kind of membrane material with better performance and broadly applied in water purification, biochemistry separation, Chinese traditional herb drugs extraction and concentration, etc. But PSF membrane has a tendency to be contaminated for its hydrophobicity, which can result in declining of flux and life of the membrane. To enhance the capability of PSF membrane, such as tensile strength, hydrophilic property, anti-fouling ability, novel organic–inorganic composite membranes were prepared by a process of adding modified nanosilica with higher activity and hydrophilic property to the porous matrix of PSF. Ce-doped nonstoichiometric nanosilica (modified nanosilica) was synthesized by doping the rare earth Ce element. Composite membranes were prepared by sol–gel process and characterized by test of tensile strength, contact angel, porosity, infrared spectroscope (IR), environment scanning electron microscope (ESEM) and performance for oil–water separation. The results show that tensile strength is improved to a large extent and contact angel reduces from 78.6° to 41.7°; porosity reaches 75%. IR spectrum of the composite membrane indicates that the cerium element has entered into the framework of nanosilica. ESEM micrographs indicate that the composite membrane owning the asymmetry structure has two layers of compact layer and porous layer and that modified nanosilica is uniformly dispersed in PSF. The flux in treatment of wastewater containing oil is greatly increased, so it indicates that the anti-fouling ability is significantly enhanced and treatment of wastewater containing oil using the composite membrane developed is feasible and desirable.
Co-reporter:Y. Q. Zhang;E. H. Fu;J. H. Liang
Chemical Engineering & Technology 2008 Volume 31( Issue 10) pp:1510-1515
Publication Date(Web):
DOI:10.1002/ceat.200700407
Abstract
The pretreatment and saccharification process of lignocellulose were subjected to ultrasonic waves to enhance the saccharification rate. The morphology, structure and crystal performance of the original and treated lignocellulose samples were characterized by SEM and FTIR. Moreover, the effect of different pretreatment methods on the structure of the raw materials and the influence of ultrasonic waves on the saccharification rate, were studied. SEM photographs show that the surface conformation of the granulated raw material is not changed, because the energy of the ultrasonic vibration is too low to cause changes to its structure. A FTIR spectrum shows that the ultrasonically assisted alkali pretreatment effectively destroys the intermolecular hydrogen bonding of lignocellulose and decreases its crystallinity. The catalytic efficiency of cellulase was increased by 70 % under ultrasonic treatment. Therefore, the ultrasonically assisted alkali pretreatment can improves the degradation rate of lignin and the saccharification rate of zymohydrolysis. The mechanism of the effect of ultrasonic waves on the enzymatic catalysis process is also discussed in detail.
Co-reporter:Yuqing Zhang;Yahui Zhang;Zhen Qin;Zhenrong Ma
Frontiers of Chemistry in China 2008 Volume 3( Issue 3) pp:
Publication Date(Web):2008 September
DOI:10.1007/s11458-008-0052-x
One kind of built-in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting technology by the following steps: synthesis of precursor from the reaction between water soluble rutin (as template molecule) and the functional monomer chloropropyltriethoxysilane, co-hydrolysis of the precursor and tetraethoxysilane (TEOS), sol-gel aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high adsorption capacity for rutin, and good adsorption selectivity towards rutin even under the interference of a flavone with a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR spectra indicate that new bond was generated during the recognition process.
Co-reporter:Y. Q. Zhang;J. H. Liang;E. H. Fu;B. X. Li
Chemical Engineering & Technology 2007 Volume 30(Issue 11) pp:
Publication Date(Web):21 SEP 2007
DOI:10.1002/ceat.200700234
Multi-enzymatic catalysis combined with acid hydrolysis is studied in order to enhance the efficiency of the enzymatic catalysis and reduce the mass transfer resistance from starch and cellulose in the extraction of diosgenin from Dioscorea zingiberensis C. H. Wright. The cellulase is modified by polyethylene to increase its optimal reaction temperature and pH value. The modified cellulase shows better thermostability and resistance to alkali. The modified cellulase, α-amylase and β-glycosidase are used to construct the multi-enzyme and multi-enzyme catalysis is used as a pretreatment process. Compared to primary industrial techniques including acid hydrolysis, spontaneous fermentation and enzymatic catalysis, conventional techniques are optimized by using multi-enzymatic catalysis together with acid hydrolysis because of the higher reaction efficiency and lower levels of manipulation required. The purity of the product is more than 96 % with this technique, and the melting point is 205–207 °C. The diosgenin yield rate and the extraction rate reached are 2.43 % and 98 %, respectively. IR and 1H NMR spectroscopy were used to confirm the structure of the product.
Co-reporter:Yuqing Zhang, Fanglong Liu, Yiren Lu, Lili Zhao, Lixin Song
Desalination (2 September 2013) Volume 324() pp:118-126
Publication Date(Web):2 September 2013
DOI:10.1016/j.desal.2013.06.007
•Phosphorylated TiO2–SiO2 (PTS) particles were successfully prepared.•PTS/PSF membrane was fabricated by doping PTS particles.•The PTS/PSF membrane shows good hydrophilicity and anti-compaction capability.•PTS/PSF membrane is desirable for treating wastewater containing oil.Phosphorylated TiO2–SiO2 (PTS) particles with good hydrophilicity were first synthesized by the sol–gel method and then added into a polysulfone (PSF) membrane to prepare a PTS/PSF composite membrane through a phase inversion process. The hydrophilic properties of the PTS particles were explained by a model proposed by Tanabe. The properties of the particles and membranes were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), contact angle of water, permeate flux, tensile strength and practical applications of membranes respectively. The results show that PTS particles are uniformly dispersed in the PTS/PSF composite membrane and the water contact angle of the membrane declines from 78.0° to 45.5°, which indicates the good hydrophilic nature of PTS particles. A comparison test of the PTS/PSF composite membrane demonstrates its higher hydrophilicity, anti-fouling and anti-compaction characteristics than other membranes, such as PSF, SiO2/PSF and phosphorylated Zr-doped hybrid silica (SZP)/PSF. Therefore, PTS/PSF composite membranes are desirable for treating wastewater containing oil.
Co-reporter:Simeng Zhang, Rongshu Wang, Shaofeng Zhang, Guoling Li, Yuqing Zhang
Desalination (2 January 2014) Volume 332(Issue 1) pp:109-116
Publication Date(Web):2 January 2014
DOI:10.1016/j.desal.2013.11.008
•PSNTs/PVDF composite membrane was successfully prepared.•PSNTs/PVDF composite membrane has the better integrative properties.•PSNTs/PVDF composite membrane has the better anti-fouling abilities.•PSNTs/PVDF composite membrane is desirable in the treatment of sewage.PVDF membranes are broadly applied in many fields owing to their good physicochemical stability, resistance to oxidation and chlorine. However when treating with wastewater, PVDF membranes are easily contaminated by pollutant, degrading their properties due to the hydrophobicity and poor anti-compaction capabilities, which can result in the decline of flux and lifespan of the membrane and limit their application in large scale. To enhance the integrative capabilities of PVDF membrane, phosphorylated silica nanotubes (PSNTs) were doped to PVDF to prepare a novel PSNTs/PVDF composite membrane through a phase inversion technique. The PSNTs/PVDF composite membranes were exposed to wastewater containing oil, and the effects of doped materials, operating pressure and operating temperature on fluxes were researched. The optimum parameters are: operating pressure is 0.1 MPa, operating temperature 25 °C. Through physical flushing and chemical cleaning, the PSNTs/PVDF membranes could still keep a high permeation flux and long lifetime. Finally, the interaction mechanism between PSNTs and PVDF membrane, the anti-fouling mechanism of PSNTs/PVDF composite membrane were explored and analyzed. The results show that the hydrophilicity, anti-fouling and anti-compaction properties of composite membrane can be obviously enhanced and hence the PSNTs/PVDF composite membrane is desirable in the treatment of wastewater containing oil and sewage.
Co-reporter:Yuqing Zhang, Lili Wang, Yan Xu
Desalination (16 February 2015) Volume 358() pp:84-93
Publication Date(Web):16 February 2015
DOI:10.1016/j.desal.2014.12.022
•ZVT are successfully prepared.•ZVT were dopped into PVDF to prepare ZVT/PVDF composite membranes.•Micro reaction locations (MRLs) are formed inside PVDF membranes.•ZVT can interact with PVDF chains by hydrogen bonds.In this paper, porous ZrO2 solid superacid shell/void/TiO2 core nanoparticles (ZVT) were firstly prepared and then doped them to polyvinylidene fluoride (PVDF) to prepare a novel composite membrane (ZVT/PVDF composite membrane) through a phase inversion process, enhancing the capabilities of anti-fouling, anti-compaction and hydrophilicity of PVDF membranes. ZVT were investigated through scanning electron microscope (SEM), transmission electron microscope (TEM) and Fourier transform infrared (FT-IR). The results indicate that ZVT with the diameter of around 500 nm are uniformly dispersed in PVDF membranes, the thickness of the ZrO2 shell are roughly 50 nm and the ZrO2 shell shows a porous structure, and a solid superacid ZrO2 shell on the TiO2 core is formed due to a stretching vibration peak of SO double bond at 1460 cm− 1 in FT-IR spectra; alternatively, ZrO2 solid superacid shell of ZVT with strong acidity can form hydrophilic surroundings on the surface of PVDF membranes, and abundant hydroxyl groups on the surface of ZVT interact with PVDF chains by hydrogen bonds; furthermore, micro reaction locations (MRL) existing inside channels and surface of PVDF membrane enhance its properties. Therefore, ZVT are desirable functional nanomaterials as fillers of PVDF membranes.
Co-reporter:Yuqing Zhang, Linru Tang, Xuan An, Erhong Fu, Chaofan Ma
Biochemical Engineering Journal (1 December 2009) Volume 47(Issues 1–3) pp:80-86
Publication Date(Web):1 December 2009
DOI:10.1016/j.bej.2009.07.006
Co-reporter:Yuqing Zhang, Yan Xu, Simeng Zhang, Yuyuan Zhang, Zhiping Xu
Desalination (1 August 2012) Volume 299() pp:63-69
Publication Date(Web):1 August 2012
DOI:10.1016/j.desal.2012.05.020
When treated with sewage, polysulfone (PSF) membranes have a tendency to be contaminated due to their hydrophobicity, which limits large scale applications. To enhance the hydrophilic and anti-fouling property of PSF membrane, a novel organic–inorganic composite membrane was prepared by adding sulfated Y-doped nonstoichiometric zirconia (zirconia with defects, ZD) to PSF through a sol–gel process. The composite membranes were exposed to sewage containing oil, and the effects of the added amount of ZD, oil concentration, operating pressure, temperature and time on properties of composite membrane were researched. The optimum parameters are: 15 wt.% added ZD; 80 mg/L oil concentration; 0.15 MPa operating pressure; operating temperature between 22 and 30 °C and up to 5 h of operating time. At 80 mg/L sewage containing oil, the oil retention is 99.16% and the oil concentration in the permeate is 0.67 mg/L, which meets the requirement for discharge (less than 10 mg/L). After backflushing and chemical cleaning, the composite membranes could still keep a high permeation flux. It can be concluded that the hydrophilic and anti-fouling property of composite membrane can be significantly enhanced and hence the novel composite membrane is desirable in the treatment of sewage containing oil.Highlights► Sulfated Y-doped nonstoichiometric zirconia particles (ZD) are prepared. ► ZD particles are doped into polysulfone to prepare a composite membrane. ► This composite membrane can be applied to the process of oil–water separation. ► This composite membrane has stronger hydrophilic property and anti-fouling ability.
