Co-reporter:Yuting Geng;Pan Zhang;Qiutong Wang;Yangxiu Liu
Journal of Materials Chemistry B 2017 vol. 5(Issue 27) pp:5390-5396
Publication Date(Web):2017/07/12
DOI:10.1039/C7TB00929A
Materials with Janus structures have attracted significant attention in recent years. Here, we fabricated a novel type of Janus ultrafine fiber membrane (UFM) by designing a spinneret via electrospinning and polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) Janus ultrafine fibers were successfully obtained at a large scale. The morphology, chemical composition, and solubility of the PAN/PVP Janus UFM in water were studied in detail via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR). Compared to a PAN/PVP composite UFM, the Janus UFM exhibited significant self-supporting properties when the PVP side was dissolved in water, which was attributed to the PAN side still maintaining the required net structure. Two fluorescent molecules were added to the Janus UFM to enable further characterization. The applicability of this PAN/PVP Janus UFM as a drug carrier was investigated. The results indicated ideal biphasic drug release features in the Janus UFM and that the addition of fluorescent dyes can be used to track the process of drug release. The good self-supporting properties and the biphasic drug release feature indicate the broad applicability of the PAN/PVP Janus UFM.
Co-reporter:Kai Sun;Lifang Wang;Chunzhi Wu;Jianping Deng
Advanced Materials Interfaces 2017 Volume 4(Issue 24) pp:
Publication Date(Web):2017/12/01
DOI:10.1002/admi.201700845
AbstractThe treatment of dye polluting water is one of the most important tasks that are concerned with water resources. Herein, a nanofiber composite membrane (NCM) is fabricated with an aim to effectively degrade organic dyes. First, α-Fe2O3 nanoparticles are loaded on the surface of graphene oxide (GO) sheets through hydrothermal method. Then the as-prepared α-Fe2O3@rGO sheets are deposited on polyacrylonitrile (PAN) nanofiber mat via vacuum filtration to obtain α-Fe2O3@rGO/PAN NCM. Thus, the NCM has a double-layer structure with α-Fe2O3@rGO as the upper layer and PAN nanofiber as the lower layer (support layer), providing structural advantages in photocatalytic degradation in solution. The composition, morphology, and structure of the NCM are characterized in detail. Photocatalytic experiments show that the NCM can effectively degrade a variety of organic dyes, among which the degradation rate of methylene blue is as high as 98.5% within 2 h. Moreover, the degradation rate still remains at high level after 5 cycles and the NCM remains intact, indicating the reusability of the NCM. It is in particular worth highlighting that high degradation efficiency is obtained even under natural sunlight, demonstrating great potential applications of the NCM in industrial dye wastewater treatment.
Co-reporter:Zhen Qin;Lifang Wang;Wenzheng Zhang
RSC Advances (2011-Present) 2017 vol. 7(Issue 85) pp:54213-54221
Publication Date(Web):2017/11/21
DOI:10.1039/C7RA11088J
In this study, a novel procedure of fabricating a high performance graphene oxide (GO) composite membrane with high water permeability and selectivity was developed. The GO-based composite membrane, which was fabricated by assembling GO nanosheets on a polyacrylonitrile (PAN) ultrafiltration substrate using vacuum filtration method, was cross-linked by 1,3,5-benzenetricarbonyl trichloride (TMC). Intriguingly, the cross-linking reaction that just occurred at the surface of the GO layer not only provides a stable spacing of the surface GO nanosheets, which ensures the separation accuracy of the composite membrane, but also keeps a high water transport efficiency when passing through the uncross-linked interlamination channels of the GO layer. Pervaporation performance testing, using a water/ethanol feed solution, demonstrated that the separation accuracy and water flux for the optimized surface cross-linked GO composite membrane (TGOm) were significantly better or at least comparable to the values from the GO composite membrane (GOm), and the separation factor of TGOm was enhanced almost several fold. Additionally, with the increasing temperature of the feed solution, the TGOm still maintained an “ideal” separation accuracy, indicating the fine thermostability of the cross-linked membrane.
Co-reporter:Lijing Ma, Kelan Liu, Meizhen Yin, Jiao Chang, Yuting Geng, Kai Pan
Sensors and Actuators B: Chemical 2017 Volume 238() pp:120-127
Publication Date(Web):January 2017
DOI:10.1016/j.snb.2016.07.049
•A novel fluorescent nanofibrous membrane for mercuric ion (II) detection.•The detection of mercuric ion (II) with high sensitivity and selectivity.•Good durability of the sensor contributes to economic and environmental benefits.A highly sensitive and selective fluorescent nanofibrous membrane (FNFM) for the detection of mercuric ions (II) was prepared via electrospinning and subsequent immobilization. In this process, fluorescent chemosensor dithioacetal-modified perylenediimide (DTPDI) was introduced on the surface of polyacrylonitrile (PAN) nanofibers with high stability under mechanical force by electrostatic interaction. Because DTPDI can be detached from PAN nanofibers due to the hydrolysis of dithioacetals in the presence of Hg2+ and form an oil-soluble fluorescence dye AL. According to the linear correlation between AL and Hg2+, the obtained FNFM could be employed for the detection of Hg2+. Results reveal that the FNFM exhibits high sensitivity for the detection of Hg2+ and no interference from other metal ions. The limit of detection for Hg2+ can reach as low as 1 ppb. In addition, the strong fluorescence of FNFM still can be observed even after the repeated use for 7 times. Therefore, FNFM can be developed as a rapid, portable and stable sensor for the detection of Hg2+. Moreover, FNFM can execute other functions by changing the probe immobilized on the surface of nanofiber.
Co-reporter:Jianqiang Wang, Pan Zhang, Bin Liang, Yuxuan Liu, Tao Xu, Lifang Wang, Bing Cao, and Kai Pan
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 9) pp:6211
Publication Date(Web):February 5, 2016
DOI:10.1021/acsami.5b12723
A novel graphene oxide (GO)-based nanofiltration membrane on a highly porous polyacrylonitrile nanofibrous mat (GO@PAN) is prepared for water treatment applications. GO with large lateral size (more than 200 μm) is first synthesized through an improved Hummers method and then assembled on a highly porous nanofibrous mat by vacuum suction method. The prepared GO@PAN membrane is characterized by scanning electron microscopy, transmission electron microscopy, Raman spectrum, X-ray diffraction, and so forth. The results show that graphene oxide can form a barrier on the top of a PAN nanofibrous mat with controllable thickness. The obtained graphene oxide layer exhibits “ideal” pathways (hydrophobic nanochannel) for water molecules between the well-stacked GO nanosheets. Water flux under an extremely low external pressure (1.0 bar) significantly increased due to the unique structure of the GO layer and nanofibrous support. Furthermore, the GO@PAN membrane shows high rejection performance (nearly 100% rejection of Congo red and 56.7% for Na2SO4). A hydrophilic–hydrophobic “gate”-nanochannel model is presented for explaining the water diffusion mechanism through the GO layer. This method for fabrication of the GO membrane on a highly porous support may provide many new opportunities for high performance nanofiltration applications.Keywords: electrospun; graphene oxide; nanofibrous membrane; nanofiltration; water treatment
Co-reporter:Bin Liang, Pan Zhang, Jianqiang Wang, Jin Qu, Lifang Wang, Xiuxing Wang, Chunfeng Guan, Kai Pan
Carbon 2016 Volume 103() pp:94-100
Publication Date(Web):July 2016
DOI:10.1016/j.carbon.2016.03.001
Developing graphene-based membranes is important for a wide range of applications such as in desalination, wastewater treatment, separation and purification. Herein, a novel graphene-based nanofiltration (NF) membrane was fabricated by depositing the magnesium silicate modified reduced graphene oxide (MgSi@RGO) nanosheets on a polyacrylonitrile (PAN) ultrafiltration membrane via a vacuum filtration method. The MgSi@RGO/PAN composite membrane exhibits special selectivities for separation of organic molecules. Molecule permeation through the MgSi@RGO selective skin layer was observed with the broadened nanochannels propped up by MgSi nanosheets. The rejections of different PEG molecules (PEG200, PEG400, PEG600 and PEG1000) were tested, and the experimental results and theoretical calculations showed high consistency, which means the theoretical model can be effectively used for calculating the real diameter of “pore” in NF membrane. Additionally, three dye molecules were selected to investigate the NF membrane performance, and the MgSi@RGO/PAN composite membrane showed different separation characteristics of charged molecules.
Co-reporter:Chao Luo, Xiuxing Wang, Jianqiang Wang, Kai Pan
Composites Science and Technology 2016 Volume 133() pp:97-103
Publication Date(Web):14 September 2016
DOI:10.1016/j.compscitech.2016.07.021
A series of solvent resistant magnetic polyimide/Fe3O4 (PI/Fe3O4) nanofibers were prepared by electrospinning the polyamide acid/ferric acetylacetonate (PAA/Fe(acac)3) mixed solutions and followed by a thermal treatment procedure. Samples were fully characterized in terms of FTIR, SEM, TEM, XRD and vibrating sample magnetometer (VSM). PI/Fe3O4 nanofibers structure and performance can be tuned by varying the thermal treatment procedure and Fe(acac)3 loading amount as well. Results revealed the complete transformation from PAA to PI after thermal treatment procedure, and the Fe3O4 particles dispersed relatively well, and mainly in the outer sphere of PI nanofibers under optimal conditions. VSM results showed that the saturation magnetization of PI/Fe3O4 nanofibers with a Fe(acac)3 loading amount of 21% can reach up to 10.46 emu/g. The one-pot prepared magnetic PI/Fe3O4 nanofibers were stable in most common organic solvents. This methodology can be scaled up and the obtained nanofibers could be an encouraging candidate for the template of adsorption, separation and catalysis, especially in the organic solvent phase.
Co-reporter:Jianqiang Wang;Keying Song;Bing Cao;Li Li
Journal of Chemical Technology and Biotechnology 2016 Volume 91( Issue 3) pp:777-785
Publication Date(Web):
DOI:10.1002/jctb.4644
Abstract
BACKGROUND
Polyimide (PI) solvent-resistant nanofiltration (SRNF) membranes were prepared by a two-step method. The polyamic acid (PAA) precursor was synthesized first, and then PAA membranes were obtained via a non-solvent induced phase separation method. Finally, the PAA membranes were transformed into PI membranes by the thermal imidization method. The effect of molecular weight of precursor on the structure and performance of PI membranes was investigated in detail. In addition, the influence of other processing parameters, such as evaporation time and immersion time in the coagulation bath, on the performance of PI membranes prepared from PAA with different molecular weights was also investigated.
RESULTS
The results showed that the structure of PI membrane varied with PAA molecular weight. The PI membranes prepared from low molecular weight PAA failed to form a defect-free membrane with enough strength, and resulted in high flux but low rejection. Accordingly, PI membranes processed from PAA with high molecular weight retain rejection higher than 90% of FCF with decreased flux. The results also indicated that the optimized molecular weight of PAA should be between 1.23 × 105 g mol−1 and 2.44 × 105 g mol−1 to prepare defect-free PI membrane for nanofiltration. The results also showed that the performance of the PI membranes can be controlled by adjusting the evaporation time, immersion time, and also the operating pressure.
CONCLUSIONS
The PAA molecular weight has a great effect on the morphology and performance of PI membranes. A suitable PAA molecular weight is necessary for preparing defect-free PI nanofiltration membrane. © 2015 Society of Chemical Industry
Co-reporter:Peng Jia;Jiao Chang;Jianqiang Wang;Pan Zhang;Bing Cao;Yuting Geng;Xiuxing Wang ; Kai Pan
Chemistry – An Asian Journal 2016 Volume 11( Issue 1) pp:86-92
Publication Date(Web):
DOI:10.1002/asia.201500777
Abstract
We report a new simple method to fabricate a highly active SERS substrate consisting of poly-m-phenylenediamine/polyacrylonitrile (PmPD/PAN) decorated with Ag nanoplates. The formation mechanism of Ag nanoplates is investigated. The synthetic process of the Ag nanoplate-decorated PmPD/PAN (Ag nanoplates@PmPD/PAN) nanofiber mats consists of the assembly of Ag nanoparticles on the surface of PmPD/PAN nanofibers as crystal nuclei followed by in situ growth of Ag nanoparticles exclusively into nanoplates. Both the reducibility of the polymer and the concentration of AgNO3 are found to play important roles in the formation and the density of Ag nanoplates. The optimized Ag nanoplates@PmPD/PAN nanofiber mats exhibit excellent activity and reproducibility in surface-enhanced Raman scattering (SERS) detection of 4-mercaptobenzoic acid (4-MBA) with a detection limit of 10−10 m, making the Ag nanoplates@PmPD/PAN nanofiber mats a promising substrate for SERS detection of chemical molecules. In addition, this work also provides a design and fabrication process for a 3D SERS substrate made of a reducible polymer with noble metals.
Co-reporter:Jiao Chang, Jianqiang Wang, Jin Qu, Yan Vivian Li, Lijing Ma, Lifang Wang, Xiuxing Wang and Kai Pan
Environmental Science: Nano 2016 vol. 3(Issue 4) pp:894-901
Publication Date(Web):28 Jun 2016
DOI:10.1039/C6EN00088F
α-Fe2O3 nanoparticles have been widely used in water purification because of their effective adsorption performance. However, aggregation and difficulty in separation limit their practical application. Herein, we presented a polyacrylonitrile (PAN) nanofiber mat decorated with α-Fe2O3 as an adsorbent for effective removal of Pb2+ from contaminated water, which can solve the above problems easily. The α-Fe2O3/PAN nanofiber mats were prepared via electrospinning followed by a facile hydrothermal method and characterized by SEM, HRTEM, FTIR and XRD. We demonstrated that the formation mechanism of α-Fe2O3 anchored on the PAN nanofiber surface consists of the adsorption of iron ions on the surface of PAN, and then the nucleation and growth of α-Fe2O3. The pH value of FeCl3 solution has a great impact on the formation process of the α-Fe2O3/PAN nanofiber mat, which leads to the variation of morphology and quantity of the coating coverage. When the pH value was 2.4, polyhedral particles were coated on PAN nanofibers uniformly and the optimized α-Fe2O3/PAN nanofiber mat was obtained. Control experiments were carried out to quantify the adsorption capacities of different samples and adsorption kinetics. The isotherm data from our experiments fitted well to the Langmuir model and the adsorption process can be described using the pseudo-second-order model. Finally, the adsorption mechanism for Pb2+ was investigated and the results revealed that ion exchange between the proton of surface hydroxyl groups and Pb2+ accounted for the adsorption.
Co-reporter:Bin Liang, Wu Zhan, Genggeng. Qi, Sensen Lin, Qian Nan, Yuxuan Liu, Bing Cao and Kai Pan
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:5140-5147
Publication Date(Web):20 Jan 2015
DOI:10.1039/C4TA06573E
As an emerging technology, pervaporation (PV) has shown great promise in fresh water production from salty water. However, the low separation efficiencies of the present membranes hinder their practical applications. Here, thin graphene oxide (GO) films with 2D nanochannels were fabricated on polyacrylonitrile (PAN) ultrafiltration membranes using a vacuum filtration-assisted assembly method. The GO/PAN composite membrane exhibits a high water flux of up to 65.1 L m−2 h−1 with high rejection (about 99.8%) for desalination by pervaporation at 90 °C. It is noteworthy that the composite membranes show high performances in treating high-salinity water, even at salt concentrations of up to 100000 ppm. This makes it possible to use GO-based membranes for seawater desalination, brackish water desalination and reverse osmosis concentrate treatment.
Co-reporter:Peng Jia, Bing Cao, Jianqiang Wang, Jin Qu, Yuxuan Liu and Kai Pan
Analyst 2015 vol. 140(Issue 16) pp:5707-5715
Publication Date(Web):19 Jun 2015
DOI:10.1039/C5AN00716J
We report a facile method to synthesise flexible 3D surface-enhanced Raman scattering (SERS) substrates, using poly-m-phenylenediamine/polyacrylonitrile (PmPD/PAN) nanofiber mats as templates to self-assemble citrate-stabilized Ag nanocrystals (AgNCs), such as Ag nanoparticles (AgNPs), Ag nanotriangles (AgNTs) or Ag nanodisks (AgNDs). The SERS performances of AgNC@2D and AgNC@3D substrates were compared using 4-MBA as the probe molecule. The effect of the extinction wavelength as well as the density and morphology of the AgNCs on the SERS enhancement effect was explored. The results suggest that the 3D AgNT@PmPD/PAN nanofiber mat exhibits the highest SERS sensitivity and the lowest relative standard deviation (RSD) value. The detection limit of 4-MBA is as low as 10−8 M, making the nanofiber mat a promising candidate for the SERS detection of chemical molecules. In addition, this study provides a simple route for the fabrication of SERS substrates with different types of noble metals and materials with strong SERS enhancement performance.
Co-reporter:Peng Jia, Jin Qu, Bing Cao, Yuxuan Liu, Chao Luo, Junhu An and Kai Pan
Analyst 2015 vol. 140(Issue 15) pp:5190-5197
Publication Date(Web):15 May 2015
DOI:10.1039/C5AN00305A
We report chemical deposition of silver nanocrystals (AgNCs) of different sizes and morphologies, such as polyhedra and plates, on a polyacrylonitrile (PAN) nanofiber mat. High performance surface-enhanced Raman scattering (SERS) substrates are achieved. The effect of the experimental parameters, such as the temperature, concentration and pH of [Ag(NH3)2]OH aqueous solution, on the morphology evolution and density of AgNCs is systematically investigated. The results suggest that the optimized nanofiber mat exhibits a significant SERS performance with superior stability and reproduction, and the SERS enhancement factor (EF) can reach as high as 108 for 4-mercaptobenzoic acid (4-MBA). The optimized nanofiber mat also shows high SERS activity for p-aminothiophenol (4-ATP) over the whole nanofiber mat demonstrating the feasibility for detection of both analytes. The detection limit of 4-MBA and 4-ATP is as low as 10−9 M and 10−10 M respectively, making the nanofiber mat a promising candidate for SERS detection of chemical pollutants.
Co-reporter:Kai Pan;Haizhu Li;Bin Liang;Genggeng Qi;Bing Cao
Polymer International 2015 Volume 64( Issue 1) pp:138-145
Publication Date(Web):
DOI:10.1002/pi.4772
Abstract
A versatile method is described to synthesize a new family of solvent-responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2-bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track-etched membrane followed by room-temperature ATRP grafting of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) (P(HEMA-co-DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo-crosslinkable PET-g-PHEMA/CA membrane and PET-g-P(HEMA/CA-co-DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA-co-DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry
Co-reporter:Yuxuan Liu, Bing Cao, Peng Jia, Junhu An, Chao Luo, Lijing Ma, Jiao Chang, and Kai Pan
The Journal of Physical Chemistry A 2015 Volume 119(Issue 25) pp:6661-6667
Publication Date(Web):June 3, 2015
DOI:10.1021/acs.jpca.5b02325
Surface molecular imprinting in layer-by-layer (SMI-LbL) film is known as a facile and effective strategy to build imprinting sites that are more accessible to template molecules compared with molecular imprinting in polymers. Herein, we accomplished the formation of SMI-LbL film on electrospun nanofibers for the first time. The SMI-LbL nanofibers were prepared by a template-induced LbL process on the polyacrylonitrile (PAN) nanofiber substrates, followed by postinfiltrating and photo-cross-linking of photosensitive agent 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS). The obtained nanofiber mat maintained the nanofibrous structure and showed rapid absorption and extraction of template molecules of meso-tetra(4-carboxyphenyl)–porphine (Por). The binding capacity of Por reached 2.1 mg/g when 3.5 bilayers were deposited on the nanofibers. After six cycles of extraction and reabsorption, the binding capacity of Por remained at 83%. Moreover, the absorption results of the targeted templated molecule of Por and the control molecule of Fast Green, which had a very similar chemical structure and charge status to Por, indicated the specific absorption for template molecule of Por. Thus, a surface molecular imprinted nanofiber mat with high selectivity of the templated molecule has been demonstrated.
Co-reporter:Ting Qu, Kai Pan, Li Li, Bin Liang, Lei Wang, and Bing Cao
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 19) pp:8228
Publication Date(Web):April 28, 2014
DOI:10.1021/ie5012905
The morphology and crystallization properties of poly(vinylidene fluoride) ultrafiltration membranes prepared by the phase inversion method were investigated under ultrasound-assisted conditions in a coagulation bath. All the membranes showed improved performance compared with that of the pristine membrane, including preferable morphology, higher porosity, and higher flux for water and a Rose Bengal (RB) aqueous solution. With an increase in the ultrasonic intensity, the flux of membranes for both water and RB aqueous solution increased gradually, while the rejection by all membranes was nearly 80%. The porosity was measured by the percentage water content. Phase separation was accelerated and macrovoids developed with an increase in ultrasonic intensity, resulting in an improvement in membrane porosity. The crystalline structure was assessed by wide-angle X-ray diffractometry and attenuated total reflectance Fourier transform infrared spectroscopy. It was also shown that the β crystalline phase was partly converted to the α crystalline phase in the ultrasound-assisted phase inversion process. Membranes prepared by ultrasound-assisted phase inversion exhibited elongation greater than that of the pristine membrane.
Co-reporter:Jianqiang Wang, Chao Luo, Genggeng Qi, Kai Pan, Bing Cao
Applied Surface Science 2014 Volume 316() pp:245-250
Publication Date(Web):15 October 2014
DOI:10.1016/j.apsusc.2014.07.198
Highlights
- •
PAN/PPy core/shell nanofiber used for Cr(VI) removal.
- •
Adsorption mechanisms were investigated.
- •
Selective adsorption performances were investigated.
Co-reporter:Lei Wang, Kai Pan, Li Li, and Bing Cao
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 15) pp:6401-6408
Publication Date(Web):March 11, 2014
DOI:10.1021/ie4042388
The hydrophilic polyvinylidene fluoride (PVDF) material was prepared by ozone-induced grafting polymerization of acrylic acid on PVDF chains, and used for preparing oil/water separation ultrafiltration membranes by the nonsolvent induced phase separation method. The effect of membrane casting conditions was studied, and the results showed that N-methyl-2-pyrrolidone (NMP) present in the coagulation bath affected the membrane surface hydrophilicity as well as the membrane structure, and that casting solution concentration and air exposure time affected pore size but had little influence on surface hydrophilicity. The effect of material hydrophilicity and pore size was investigated, and the results indicated that improvement in hydrophilicity not only increased water flux itself, but also enabled high oil retention of membranes with larger pore sizes which had much higher water flux. The highest flux for the membranes with kerosene retention over 90% can reach over 300 L/m2h. The membranes showed good reusability under simple back flush.
Co-reporter:Kai Pan;Ruimin Ren;Bin Liang;Li Li;Haizhu Li;Bing Cao
Journal of Applied Polymer Science 2014 Volume 131( Issue 20) pp:
Publication Date(Web):
DOI:10.1002/app.40912
ABSTRACT
pH-responsive polyethylene terephthalate (PET) track-etched membranes were synthesized by grafting 2-hydroxyethyl-methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH-responsive characteristics of PET-g-poly(2-hydroxyethyl-methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH-response permeation to environmental pH values. Desired pH-responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40912.
Co-reporter:Ling Liu, Xiaojun Wang, Yuyu Wang, Li Li, Kai Pan, Jie Yang, Bing Cao
Materials Letters 2014 Volume 132() pp:11-14
Publication Date(Web):1 October 2014
DOI:10.1016/j.matlet.2014.05.154
•Polyarylene sulfide sulfone (PASS) was first used for preparing SRNF membranes.•PASS nanofiltration membranes treated by five solvents retained most properties.•PASS nanofiltration membranes have a high water flux of 59.5 L h−1 m−2 at 0.5 MPa.In this study, polyarylene sulfide sulfone (PASS) was first used for preparing asymmetric membranes by the non-solvent induced phase separation for organic nanofiltration. Structure of the PASS membrane was characterized by scanning electron microscopy (SEM) and the performance of the membranes were investigated by water permeability, dye rejection and solvent resistance measurement. Results showed that the PASS nanofiltration membranes had an asymmetric structure with a skin layer. Additionally, the PASS membranes had a high water flux of 59.5 L h−1 m−2 and an almost complete rejection of Rose Bengal. After treatment with five different solvents, the PASS membrane retained most initial properties. Especially, the membranes treated with ethyl acetate had the best performance with 64.9 L h−1 m−2 of water flux and a high rejection ratio (99.9%) of Rose Bengal.
Co-reporter:Kai Pan;Hongxia Gu;Bing Cao
Polymer Bulletin 2014 Volume 71( Issue 2) pp:415-431
Publication Date(Web):2014 February
DOI:10.1007/s00289-013-1068-z
A novel thin-film composite (TFC) nanofiltration membrane was prepared through interfacial polymerization on surface hydrophilic-modified polypropylene (PP) membrane. Firstly, PP membranes were hydrophilized to ensure the formation of separation layer on it by interfacial polymerization. In this work, the UV-induced grafting of acrylic acid (AAc) was applied to modify the surface of PP membranes. Secondly, the TFC membranes were fabricated on PP membranes with different grafting degrees of AAc via interfacial polymerization. Effects of the UV-induced graft polymerization conditions, such as benzophenone concentration, monomer concentration and UV irradiation time, were systematically investigated. The surface-modified PP membranes and the TFC membranes were characterized with water contact angle measurement, attenuated total reflectance infrared and scanning electron microscopy. Furthermore, the permeation experiments were employed to evaluate the membranes’ nanofiltration performance.
Co-reporter:Jianqiang Wang, Kai Pan, Emmanuel P. Giannelis and Bing Cao
RSC Advances 2013 vol. 3(Issue 23) pp:8978-8987
Publication Date(Web):18 Mar 2013
DOI:10.1039/C3RA40616D
Polyacrylonitrile/polyaniline core/shell nanofibers were prepared via electrospinning followed by in situ polymerization of aniline. Nanofibers with different morphology were obtained by changing the polymerization temperature. When used as absorbent for Cr(VI) ions, the core/shell nanofiber mats exhibit excellent adsorption capability. The equilibrium capacity is 24.96, 37.24, and 52.00 mg g−1 for 105, 156, and 207 mg L−1 initial Cr(VI) solution, respectively, and the adsorption capacity increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(VI) ions in the presence of competing ions albeit a small decrease in adsorption is observed. The mats can be regenerated and reused after treatment with NaOH making them promising candidates as practical adsorbents for Cr(VI) removal.
Co-reporter:Kai Pan;Ruimin Ren;Haizhu Li;Bing Cao
Polymers for Advanced Technologies 2013 Volume 24( Issue 1) pp:22-27
Publication Date(Web):
DOI:10.1002/pat.3044
A dual stimuli-responsive (pH and thermo) polyethylene terephthalate (PET) track-etched membrane has been prepared using atom transfer radical polymerization (ATRP). First, ATRP initiator 2-bromoisobutyryl bromide was anchored onto the membrane surface. Then, 2-hydroxyethyl-methacrylate (HEMA) and N-isopropylacrylamide (NIPAAm) were grafted onto the membrane surface using ATRP. X-ray photoelectron spectroscopy, ATR-Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were used to characterize the membrane structure and thermal properties; water flux measurement was used to investigate the double stimuli-responsive property of the obtained membrane. The results indicate that the PHEMA and PNIPAAm binary grafted PET track-etched membrane has double environmental responsiveness. This method provides a potential modification method for preparing functional membranes. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Bing Fang;Qinghan Meng ;Bing Cao
Polymer International 2012 Volume 61( Issue 1) pp:111-117
Publication Date(Web):
DOI:10.1002/pi.3154
Abstract
This study investigated the preparation of polyimide solvent-resistant nanofiltration membranes by a two-step method (casting the membrane first and then crosslinking by the thermal imidization method). The influences of polymer concentration, thickness of membranes, temperature of the imidization, phase inversion time and thermal imidization procedure were studied. The membranes with the highest rejection rate of Fast Green FCF (molecular weight 808.86 g mol−1) were prepared in the following conditions: polymer concentration 13 wt%, phase inversion time 1 h, membrane thickness 150 µm and thermal imidization procedure 200 °C for 2.5 h, 250 °C for 2 h and 300 °C for 2 h in a vacuum environment; the heating rate was 5 °C min−1. The membrane was stable in most of the solvents tested and the fluxes of some common solvents were equal to or higher than a number of commercial solvent-resistant nanofiltration membranes. A much higher rejection of dyes in water than in methanol was observed in the filtration experiments and a new way to explain it was developed. Copyright © 2011 Society of Chemical Industry
Co-reporter:Kai Pan;Xiaowei Zhang;Jie Zhu ;Bing Cao
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:1948-1952
Publication Date(Web):
DOI:10.1002/pat.1699
Abstract
Regenerated cellulose (RC) membranes which have pH modulated permeability have been prepared by anchoring the hydroxyl groups on the membrane surface with 2-bromoisobutyryl bromide, followed by grafting with acrylic acid (AA) using atom transfer radical polymerization (ATRP). The obtained membranes were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared attenuated total reflection spectrometer (ATR-FTIR), scanning electron microscopy (SEM), TGA and the results showed that AA had been grafted onto the membrane surfaces successfully. Then the pH modulated permeability properties were tested by water flux measurement. All results show that the pH modulated permeability properties of a RC membrane can be obtained by surface-initiated ATRP. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Kai Pan, Xiaowei Zhang, Ruimin Ren, Bing Cao
Journal of Membrane Science 2010 Volume 356(1–2) pp:133-137
Publication Date(Web):1 July 2010
DOI:10.1016/j.memsci.2010.03.044
Double stimuli-responsive regenerated cellulose membranes have been prepared using atom transfer radical polymerization (ATRP) method. Firstly, the ATRP initiator of 2-bromoisobutyryl bromide was anchored on the surface of regenerated cellulose membranes. Then acrylic acid (AAc) and N-isopropylacrylamide (NIPAAm) were grafted onto the membrane surface step by step using ATRP method. The grafted chain length could be controlled by polymerization time. The uniform chain length could make the grafted copolymer (P(AAc)-b-P(NIPAAm)) as clear and different aggregate phase. So, the double stimuli-responsive property of block copolymer grafted membrane was distinct. Also, the results showed that the stimuli-responsive property of membrane was not a simple adding of two different stimuli-responsive properties, such as pH-responsive and thermo-responsive but more complicated responses to the changes of pH values and temperatures because of the reciprocity of different molecules. In this paper, the membrane was characterized by XPS, ATR-FTIR, TGA and SEM. The double stimuli-responsive properties of grafted membranes were measured by water flux measurement.
Co-reporter:Kai Pan;Xiaowei Zhang ;Bing Cao
Polymer International 2010 Volume 59( Issue 6) pp:733-737
Publication Date(Web):
DOI:10.1002/pi.2773
Abstract
Using atom transfer radical polymerization (ATRP), thermo-responsive regenerated cellulose membranes were synthesized. Regenerated cellulose membranes were firstly modified by reacting the hydroxyl groups on the surface with 2-bromoisobutyryl bromide, followed by grafting with poly(N-isopropylacrylamide). The membranes had obvious thermally modulated permeability properties. Analysis was carried out by means of X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results showed that N-isopropylacrylamide had been grafted successfully on the surface of the regenerated cellulose membranes. The thermally modulated permeability properties of the grafted membranes were studied using water flux measurements. It was found that the thermally modulated permeability properties of a cellulose surface can be tailored by the use of the ATRP method. Copyright © 2010 Society of Chemical Industry
Co-reporter:Jianqiang Wang, Tianjie Wang, Li Li, Peixin Wu, Kai Pan, Bing Cao
Journal of Water Process Engineering (September 2014) Volume 3() pp:98-104
Publication Date(Web):1 September 2014
DOI:10.1016/j.jwpe.2014.05.015
Poly(glycidyl methacrylate-t-N-methyl-d-glucamine) (P(GMA-t-NMDG)) functionalized polyacrylonitrile (PAN) nanofibers were prepared via electrospinning followed by surface modification. The functionalized PAN nanofiber mat was used for boric acid removal from aqueous solutions. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of vicinal polyalcohol groups on the surface of these nanofibers. Surface morphology of PAN-P(GMA-t-NMDG) nanofiber mat was studied by SEM. The analysis results from inductively coupled plasma mass spectrometry show that the boron adsorption process is pH-dependent with a maximum adsorption removal ratio at a pH value of 6.0–7.0. The as-functionalized PAN-P(GMA-t-NMDG) nanofiber mat is very effective for boric acid removal at extremely low concentrations which may find the potential application for further boric acid removal from the RO permeates. Meanwhile, the PAN-P(GMA-t-NMDG) nanofiber mat also demonstrates outstanding reusability.
Co-reporter:Kai Pan, Peng Fang, Bing Cao
Desalination (15 May 2012) Volume 294() pp:36-43
Publication Date(Web):15 May 2012
DOI:10.1016/j.desal.2012.03.007
Interfacial polymerization (IP) is a powerful technique for the fabrication of thin film composite (TFC) membranes. In this work, porous polypropylene fiber films were used as a support to fabricate TFC nanofiltration membrane using IP technique. Firstly, the surface of polypropylene fiber film was hydrophilized by introducing peroxide onto the membrane surface using ozone treatment followed by grafting acrylamide. And then interfacial polymerization could be successfully proceeding on the hydrophilized PP membrane. The monomeric system chosen for IP was m-phenylenediamine (MPDA) and trimesoyl chloride (TMC). The ozone treatment time was investigated, and in the range of 5–10 min ozone treatment time, the PP fiber membrane had an available amount of peroxides for grafting while keeping the mechanical strength. The characteristics of the original membrane, grafted membrane and TFC membrane were studied with various analytical methods, such as SEM and FTIR-ATR. Meanwhile, the nanofiltration performance was evaluated with aqueous solutions of Na2SO4 (2 g/L) and Fast Green FCF (MW 808.84, 10 mg/L). The rejection rate of 60% and 90% were achieved for Na2SO4 and Fast Green FCF, respectively, at a transmembrane pressure of 0.5 MPa.Highlights► Hydrophilic modification of PP membrane. ► Thin film composite NF membrane by interfacial polymerization on PP support. ► Hydrophilicity of the support is the main factor.
Co-reporter:Bin Liang, Kai Pan, Li Li, Emmanuel P. Giannelis, Bing Cao
Desalination (15 August 2014) Volume 347() pp:199-206
Publication Date(Web):15 August 2014
DOI:10.1016/j.desal.2014.05.021
•A novel facile method for preparing pervaporation composite membranes•Pervaporation composite membrane for water desalination with high flux•Relationship between top dense layer thickness and mass transfer efficiencyA three-layer thin film nanofibrous pervaporation composite (TFNPVC) membrane was prepared by sequential deposition using electrospraying/electrospinning. The poly(vinyl alcohol) (PVA) top barrier layer was first electrosprayed on aluminum foil and its thickness can be easily controlled by adjusting the collecting time. Next a polyacrylonitrile (PAN) nanofibrous scaffold was deposited by electrospinning as a mid-layer support. A nonwoven PET layer is used to complete the composite membrane. The pervaporation desalination performance of TFNPVC membranes was tested using NaCl solutions at 100 Pa and at room temperature. The TFNPVC membranes show excellent desalination performance (high water flux and salt rejection > 99.5%) for different salt concentrations with virtually no change in performance after 50 h of operation.
Co-reporter:Bin Liang, Wu Zhan, Genggeng. Qi, Sensen Lin, Qian Nan, Yuxuan Liu, Bing Cao and Kai Pan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN5147-5147
Publication Date(Web):2015/01/20
DOI:10.1039/C4TA06573E
As an emerging technology, pervaporation (PV) has shown great promise in fresh water production from salty water. However, the low separation efficiencies of the present membranes hinder their practical applications. Here, thin graphene oxide (GO) films with 2D nanochannels were fabricated on polyacrylonitrile (PAN) ultrafiltration membranes using a vacuum filtration-assisted assembly method. The GO/PAN composite membrane exhibits a high water flux of up to 65.1 L m−2 h−1 with high rejection (about 99.8%) for desalination by pervaporation at 90 °C. It is noteworthy that the composite membranes show high performances in treating high-salinity water, even at salt concentrations of up to 100000 ppm. This makes it possible to use GO-based membranes for seawater desalination, brackish water desalination and reverse osmosis concentrate treatment.
Co-reporter:Jiao Chang, Jianqiang Wang, Jin Qu, Yan Vivian Li, Lijing Ma, Lifang Wang, Xiuxing Wang and Kai Pan
Environmental Science: Nano 2016 - vol. 3(Issue 4) pp:NaN901-901
Publication Date(Web):2016/06/28
DOI:10.1039/C6EN00088F
α-Fe2O3 nanoparticles have been widely used in water purification because of their effective adsorption performance. However, aggregation and difficulty in separation limit their practical application. Herein, we presented a polyacrylonitrile (PAN) nanofiber mat decorated with α-Fe2O3 as an adsorbent for effective removal of Pb2+ from contaminated water, which can solve the above problems easily. The α-Fe2O3/PAN nanofiber mats were prepared via electrospinning followed by a facile hydrothermal method and characterized by SEM, HRTEM, FTIR and XRD. We demonstrated that the formation mechanism of α-Fe2O3 anchored on the PAN nanofiber surface consists of the adsorption of iron ions on the surface of PAN, and then the nucleation and growth of α-Fe2O3. The pH value of FeCl3 solution has a great impact on the formation process of the α-Fe2O3/PAN nanofiber mat, which leads to the variation of morphology and quantity of the coating coverage. When the pH value was 2.4, polyhedral particles were coated on PAN nanofibers uniformly and the optimized α-Fe2O3/PAN nanofiber mat was obtained. Control experiments were carried out to quantify the adsorption capacities of different samples and adsorption kinetics. The isotherm data from our experiments fitted well to the Langmuir model and the adsorption process can be described using the pseudo-second-order model. Finally, the adsorption mechanism for Pb2+ was investigated and the results revealed that ion exchange between the proton of surface hydroxyl groups and Pb2+ accounted for the adsorption.
Co-reporter:Yuting Geng, Pan Zhang, Qiutong Wang, Yangxiu Liu and Kai Pan
Journal of Materials Chemistry A 2017 - vol. 5(Issue 27) pp:NaN5396-5396
Publication Date(Web):2017/06/15
DOI:10.1039/C7TB00929A
Materials with Janus structures have attracted significant attention in recent years. Here, we fabricated a novel type of Janus ultrafine fiber membrane (UFM) by designing a spinneret via electrospinning and polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) Janus ultrafine fibers were successfully obtained at a large scale. The morphology, chemical composition, and solubility of the PAN/PVP Janus UFM in water were studied in detail via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR). Compared to a PAN/PVP composite UFM, the Janus UFM exhibited significant self-supporting properties when the PVP side was dissolved in water, which was attributed to the PAN side still maintaining the required net structure. Two fluorescent molecules were added to the Janus UFM to enable further characterization. The applicability of this PAN/PVP Janus UFM as a drug carrier was investigated. The results indicated ideal biphasic drug release features in the Janus UFM and that the addition of fluorescent dyes can be used to track the process of drug release. The good self-supporting properties and the biphasic drug release feature indicate the broad applicability of the PAN/PVP Janus UFM.
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