共查询到20条相似文献,搜索用时 31 毫秒
1.
《分离科学与技术》2012,47(7):1437-1452
Abstract Nylon 4, which possesses high mechanical strength and good affinity for water, can be considered as a liquid separation membrane. To improve the hydrophilicity of a Nylon 4 membrane for pervaporation and evapomeation processes, and to overcome the hydrolysis of polyvinyl alcohol (PVA), this study attempts to prepare a PVA-g-Nylon 4 membrane by γ-ray irradiation grafting of vinyl acetate (VAc) onto Nylon 4 membrane, followed by hydrolysis treatment. The effects of down-stream pressure, irradiation dose, VAc monomer concentration, degree of grafting, feed composition, and size of alcohols on the separation of water–alcohol mixtures were studied. The surface properties of the prepared membrane were characterized by FTIR, ESCA, and a contact angle meter. A separation factor of 13.8 and a permeation rate of 0.352 kg/m2·h can be obtained for a PVA-g-Nylon 4 membrane with a degree of grafting of 21.2% for a 90-wt% ethanol feed concentration. Compared to the pervaporation process, the evapomeation process has a significantly increased separation factor with a decreased permeation rate for the same PVA-g-Nylon 4 membrane. 相似文献
2.
A novel hydrophilic poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofiber membrane for heavy metal ions removal was fabricated by the solid phase synthesis of iminodiacetic acid (IDA) on nanofiber membrane surfaces. The hydrophilic PVA-co-PE nanofiber membranes were activated with cyanuric chloride. The IDA was then covalently linked to the activated PVA-co-PE nanofiber membranes. The chemical structures of activated and functionalized PVA-co-PE nanofiber membranes were confirmed with FTIR–ATR. The morphology of PVA-co-PE nanofiber membranes were characterized with SEM. The increase in the amount of IDA on functionalized PVA-co-PE nanofiber membranes significantly improved the adsorption amount of Cu2+. The IDA functionalized PVA-co-PE nanofiber membranes demonstrated excellent adsorption capability of Cu2+, Co2+, Zn2+ and Ni2+. The adsorption of above heavy metal ions could be repeatedly regenerated by desorbing the ions adsorbed on nanofiber membranes. The novel IDA functionalized PVA-co-PE nanofiber membranes have great potential in the application of industry and drinking water treatment. 相似文献
3.
A novel method was proposed to fabricate hollow and surface porous polystyrene (PS) fibrous membranes for the removal of oil from water. Spinning solutions were prepared by using camphene and tetraethoxysilane (TEOS) as pore-forming agents, and hollow PS fibers with 100–400 nm pores on the surface were fabricated by electrospinning and freeze-drying. The distribution and volatilization of camphene and TEOS, as well as the drying behavior of solvents in high relative humidity, were important factors in forming the porous structure of PS fibers. The specific surface area of obtained PS fibrous membranes was twice that of conventional electrospun PS fibrous membranes and displayed superhydrophobic properties. Moreover, the large adsorption storage space was formed due to the hollow structure and porous surface of PS fibers. The maximum oil adsorption capacity of the porous PS fibrous membrane was 105.4 g g−1, and was larger than that of the conventional PS fibrous membrane after repeated five times, thus making it a promising tool for oil spill cleanups. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47262. 相似文献
4.
A condensation-coupling reaction through esterification is performed between the hydroxy groups of poly(vinyl alcohol) (PVA) and the anhydride groups of methyl methacrylate (MMA)-co-maleic anhydride (MA) copolymer to produce the PVA-g-MMA/MA graft terpolymer. The MMA-co-MA copolymer was obtained by copolymerization of MA and MMA in dimethyl sulfoxide by using azobisisobutyronitrile as initiator. The structure of reaction products was confirmed by infrared analysis, and the dependence of composition, viscosity, and yield of the graft terpolymer on the MA content in MMA-co-MA as well as the concentration of the reactants fed were investigated. Mechanical properties, water content, and gel content of the membranes of terpolymers were measured over a wide range of compositions. PVA-g-MMA/N-ethylol maleimide was also synthesized by reacting the residual anhydride groups on PVA-g-MMA/MA with ethanol amine, this reaction proceeds through the PVA-g-MMA/N-ethylol maleamic acid intermediate. 相似文献
5.
Poly(methacrylic acid) (PMAA) grafted porous PE membranes (PE‐g‐PMAA) were studied. It was found that (1) a wide range of graft yields can be achieved by varying irradiation time (20–240 min) and monomer concentration (0.22M–0.66M), (2) the grafted membrane exhibits reversible permeability response, (3) the membrane shows a maximum permeability response at an intermediate permeant molecular weight due to size exclusion effect, and (4) depending on the graft yield, two types of permeability response can be obtained. These observations are consistent with our earlier study on poly(N‐isopropylacrylamide) (PNIPAAm)–grafted porous polyethylene membranes. In addition, it was observed that the solvent used during grafting may influence the graft location—presumably due to variations in pore wetting. Specifically, compared to water solvent, methanol can increase grafting inside membrane pores, an observation inferred from membrane swelling, thickness measurement, and SEM characterization. Moreover, preferential grafting inside the membrane pores, as affected by increasing methanol content in the grafting solvent, results in lower membrane permeability and a greater pore graft‐controlled type of permeability response. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 778–786, 2000 相似文献
6.
In this study, the graft copolymerization of N-hydroxymethylacrylamide (NHMAAm) with poly(vinyl alcohol) (PVA) was carried out by using potassium persulfate/N,N,N,N-tetramethylethylenediamine (K2S2O8) to improve physicochemical properties and functionality of PVA. The structures of PVA-g-poly-NHMAAm (PNHMAAm) copolymers were characterized by Fourier transform infrared, elemental analysis, nuclear magnetic resonance (1H-NMR), 13C-NMR, and size exclusion chromatography. Their thermal behaviors were investigated by differential scanning calorimetry and thermogravimetric analysis (TGA). The TGA results indicated that the graft copolymers show better thermal stability then PVA. The effects of reaction time, temperature, NHMAAm, and K2S2O8 concentrations on grafting parameters were examined. The maximum grafting yield (34.01%) was provided when reaction was carried out under optimum conditions (time = 2 hr, T = 40°C, [NHMAAm] = 0.25 M, [K2S2O8] = 4.56 × 10−3 M). Moreover, PVA-g-PNHMAAm membranes were prepared and their swelling behaviors were studied. The results demonstrated that swelling degree of graft membranes increased almost 3.5-fold compared to PVA membrane. 相似文献
7.
Yue Wu Yu Liu Ruidi Dou Wenjie Tang Bin Sun Tingting Gao Zhizhou Yang Guowei Zhou 《应用聚合物科学杂志》2020,137(16):48572
Synthesis of covalently linked porous polymers with high surface area and larger pore volume for two or more task-specific functionalities is always a big challenge. In this article, the facile Friedel–Crafts reaction is employed to construct the hierarchical hybrid porous polymers (HPPs) from tetraphenyladamantane and octavinylsilsesquioxane. The resulting polymers, HPP-1 to HPP-3, possessed the surface areas from 1356 to 1511 m2 g−1, and the pore volumes from 2.05 to 2.67 cm3 g−1. All these polymers feature micropores, mesopores, and macropores in nature. The resultant polymers exhibit high CO2 adsorption capacity up to 2.0 mmol g−1 (8.82 wt %), at 273 K, 1.0 bar, and the maximum Rhodamine B (RB) sorption capacity of 653.6 mg g−1. To illustrate the adsorption process, the effects of factors, contact time, initial concentration, temperature, and pH value on the adsorption capacity of RB were studied. The adsorption equilibrium data displayed a better fitting to the Langmuir isotherm model than the Freundlich model and the adsorption kinetics fitted well with the pseudo-second-order kinetic model. The recycle experiments displayed that the capacity recovery was still higher than 95% after four cycles. Theses polymers are promising to be the adsorbents for capturing CO2 and removing RB. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 136, 48572. 相似文献
8.
Loose nanofiltration membrane emerges as required recently, since it is hard for conventional nanofiltration membrane to fractionate mixture of dyes and salts in textile wastewater treatment. However, the polymeric membranes unavoidably suffer from membrane fouling, which was caused by the adsorption of organic pollutants (like dyes). Normally, the dye fouling layer will shrink membrane pore size, thus resulting in flux decline and rejection increase. It is thought that membrane fouling may be a double-edged sword and can be an advantage if properly utilized. Thereby, loose nanofiltration membranes were constructed here by a green yet effective method to fractionate dyes/salt mixture by taking advantage of membrane fouling without using poisonous ingredients. A commercially available polyacrylonitrile (PAN) ultrafiltration membrane with high permeability was chosen as the substrate, and dyes were used to contaminate PAN substrate and formed a stable barrier layer when adsorption of dyes reached dynamic equilibrium. The resultant PAN-direct red 80 (DR80) composite membranes displayed superior permeability (~128.4 L m−2 h−1) and high rejection (~99.9%) to DR80 solutions at 0.4 MPa. Moreover, PAN-DR80 membranes allowed fast fractionation of dyes/sodium chloride (NaCl) mixture, which maintained a negligible dye loss and a low NaCl rejection (~12.4%) with high flux of 113.6 L m−2 h−1 at 0.4 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47438. 相似文献
9.
LIXIONG ZHANG KATHERINE E. GILBERT ROBERT M. BALDWIN J. DOUGLAS WAY 《Chemical Engineering Communications》2013,200(5):665-681
Methods for preparation of carbon/silicalite-1 composite membranes have been developed. First, silicalite-1 membranes were prepared by in-situ hydrothermal synthesis on both porous alumina and metal disks. Preparation of the carbon/silicalite-1 composite membranes was accomplished by polymerizing furfuryl alcohol on the surface of the silicalite-1 membrane, followed by carbonizing the polymer layer in an inert atmosphere at 773 K. The pure silicalite-1 membrane showed no selectivity for single gases, indicating the presence of intercrystalline diffusion and viscous flow as the dominant transport mechanism. The carbon/zeolite composite membrane exhibited ideal selectivities for He/N2, CO2/N2, and N2/CH4 of 11.99, 17.12, and 3.58 at room temperature. No permeation of n-butane and i-butane for the composite membrane was detected up to temperatures of 453 K, indicating that the pore size for the composite membrane was approximately 0.4 nm. By carefully oxidizing the carbon layer in air at 623 K, the pore size of the composite membrane was adjusted such that n-butane permeation could be detected. No permeation of i-butane was apparent, suggesting that the pore size of the composite membrane had been enlarged to approximately 0.5 nm. Further oxidation of the carbon layer produced a finite n-/i-C4H4 ideal selectivity, indicating that the pore size of the membrane was now larger than 0.55 nm. Therefore, selective oxidation of the carbon layer can be used to control the pore size of the composite membrane. 相似文献
10.
Poly(methacrylic acid)‐grafted chitosan membranes (chitosan‐g‐poly(MAA)) were prepared in two sequential steps: in the first step, chitosan membranes were prepared by phase‐inversion technique and then epichlorohydrin was used as crosslinking agent to increase its chemical stability in acidic media; in the second step, the graftcopolymerization of methacrylic acid onto the chitosan membranes was initiated by ammonium persulfate (APS) under nitrogen atmosphere. The chitosan‐g‐poly(MAA) membranes were first used as an ion‐exchange support for adsorption of trypsin from aqueous solution. The influence of pH, equilibrium time, ionic strength, and initial trypsin concentration on the adsorption capacity of the chitosan‐g‐poly(MAA) membranes have been investigated in a batch system. Maximum trypsin adsorption onto chitosan‐g‐poly(MAA) membrane was found to be 92.86 mg mL?1 at pH 7.0. The experimental equilibrium data obtained for trypsin adsorption onto chitosan‐g‐poly(MAA) membranes fitted well to the Langmuir isotherm model. The adsorption data was analyzed using the first‐ and second‐order kinetic models, and the experimental data was well described by the second‐order equation. More than 97% of the adsorbed trypsin was desorbed using glutamic acid solution (0.5M, pH 4.0). In addition, the chitosan‐g‐ poly(MAA) membrane prepared in this work showed promising potential for various biotechnological applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
11.
In recent years, organic nanofibrous membranes have received more attention because of their excellent performance in wastewater treatment. In this study, the soluble poly(dimethyldiallylammonium chloride-acrylamide) (P(DMDAAC-AM)) was first synthesized by aqueous copolymerization. Afterward, cellulose acetate (CA)/P(DMDAAC-AM) composite nanofibrous membranes were electrospun and utilized to remove acid black 172 from simulated wastewater. When the proportion of P(DMDAAC-AM) to CA was 20, 30, and 40 wt %, the equilibrium adsorption capacities were 116, 159, and 192 mg g−1, respectively. The adsorption capacity of CA/P(DMDAAC-AM) composite nanofibrous membrane showed a well linear relationship with the average fiber diameter. When the average fiber diameter was 185 nm, the adsorption capacity of 231 mg g−1 was achieved. The adsorption kinetics of CA/P(DMDAAC-AM) membranes with various fiber diameters was all consistent with the pseudo-second-order model. The rate-limiting step was primarily controlled by chemisorption. The adsorption isothermal data fitted well with the Langmuir isotherm model. The prepared CA/P(DMDAAC-AM) nanofibrous membrane was effective to remove the acid black 172 in the environmental interested pH range of 4.0–10.0. As an effective dye adsorbent, CA/P(DMDAAC-AM) nanofibrous membrane shows wide application prospect with its excellent adsorption performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48565. 相似文献
12.
Isabel Jesswein Sarah Uebele Alina Dieterich Silke Keller Thomas Hirth Thomas Schiestel 《应用聚合物科学杂志》2018,135(16)
Coating processes have become an important fabrication step in membrane production, either to form a separation layer on a porous substrate or to tune specific properties. The coating procedure depends to a large extent on the membrane properties which substantially impedes a prediction of the coating thickness. To give an insight into the coating properties of various hollow fiber membranes, a selection of membranes with different pore sizes was coated with aqueous poly(vinyl alcohol) solutions at various coating velocities. It was found that material properties and pore sizes of the membranes have great influence on coating thicknesses. An intrusion of coating material into the membrane structure was determined with increasing pore size. Pure intrusion without formation of a dense surface layer took place when using a membrane with a mean pore size of ca. 500 nm. Coating results were correlated with the theoretical LLD law and for some membranes the coating thickness can be predicted quite well by the LLD law and its enhancements. When a significant amount of coating material penetrated into the membrane structure the LLD law loses its validity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46163. 相似文献
13.
Bich Ngoc Hoang Thuong Thi Nguyen Quynh Phuong Thi Bui Long Giang Bach Dai-Viet N. Vo Chinh Dung Trinh Xuan-Thanh Bui Trinh Duy Nguyen 《应用聚合物科学杂志》2020,137(30):48904
In this study, we designed a novel hydrogel composite membrane based on the combination of polyvinyl alcohol (PVA), agar, and maltodextrin through a facile solution-casting router. From Fourier-transform infrared spectroscopy, contact angle, scanning electron microscopy, and swelling analyses, the formation of hydrogen bonds between surface functional groups of PVA, agar, and maltodextrin was confirmed. As a result, the PVA/agar/maltodextrin membranes exhibited a more hydrophobic nature compared with pure PVA. The thermal stability and integrity of such obtained composite membranes were also elucidated by the evaluation of thermogravimetric analysis and mechanical behavior. Besides, the composite membrane exhibited high selective adsorption for cationic dyes, namely 20.2 mg g−1 for methylene blue and 19.17 mg g−1 for crystal violet at initial dye concentration of 100 mg/L, an adsorbent dosage of 0.1 g, contact time of 180 min, and solution pH 7, while anionic dyes such as congo red and methyl orange are approximately zero. The adsorption kinetics and isotherm of the as-prepared composite membranes were well fitted to the pseudo-second-order and Temkin model. The effect of factors, including contact time, solution pH, PVA content, and initial dye concentration on the adsorption capacity of the as-prepared composite membrane was also investigated in detail. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48904. 相似文献
14.
Poly(vinyl chloride) (PVC) was irradiated by electron beam in vacuum at 20 KGy to produce living free radicals, and then reacted with acrylic acid (AA) in solution to obtain the PVC‐g‐AA copolymers. The copolymers were characterized by Fourier transform infrared spectroscopy. Porous membranes were prepared from copolymers by the phase inversion technique. The morphology of PVC‐g‐AA membranes was studied by field emission scanning electron microscopy. The mean pore size and pore size distribution were determined by a mercury porosimeter. The mean pore size was 0.19 μm, and the bulk porosity was 56.02%. The apparent static water contact angle was 89.0°. The water drop penetration rate was 2.35 times to the original membrane. The maximum stress was 4.10 MPa. Filtration experiments were carried out to evaluate the fouling resistance of the PVC‐g‐AA membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
15.
A continuous method to prepare porous polystyrene membranes with high adsorption ability for polycyclic aromatic hydrocarbons
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A convenient and continuous method to prepare porous polystyrene (PS) membranes via a microlayer coextrusion and template method is proposed. The porous PS membranes can be obtained via the acid etching of a CaCO3 template embedded in the membranes. Scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy of the porous PS membranes show that most of the CaCO3 particles can be etched away. The effects of etching time, CaCO3 content, and membrane thickness on the porous structures are investigated, which can be used to regulate and control the porous structure. To demonstrate the adsorption performance of porous PS membranes on polycyclic aromatic hydrocarbons, pyrene is used as the model compound. Compared with that of solid PS membranes, porous PS membranes exhibit much higher adsorption performance for trace pyrene. The adsorption kinetics and isotherm of porous PS membranes can be well fit by pseudo‐second‐order kinetics and a Freundlich isotherm model. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45917. 相似文献
16.
Porous polyphenylsulfone (PPSU) membranes are facilely prepared via the nonsolvent-induced phase separation method. The typical asymmetric structure of such prepared porous membranes can be controlled by optimizing the sulfonation degree of the sulfonated poly(ether ether ketone) to 84.7% in the casting solution. Scanning electron microscopy images show that the porous membrane comprises a thin dense top skin layer, a sublayer structure with distinct long finger-like pores and the large pores in the substructure. The porous PPSU membrane was then used in vanadium flow battery (VFB). The optimized porous membrane yields an admirable performance, including excellent selectivity, chemical stability, and high columbic efficiency. Furthermore, the low cost of porous PPSU membranes indicates the promise of this technology for use in VFB applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47752. 相似文献
17.
《Reactive and Functional Polymers》2012,72(11):839-845
Poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membranes were successfully fabricated and activated with glutaraldehyde (GA) to interact with enzyme molecules. A lipase isolated from Candida rugosa was employed as a model biocatalyst and successfully immobilized onto the membrane surfaces via covalent bonds with the aldehyde groups. Scanning electron microscopy images revealed that the membranes retained uniform nanofibrous and open porous structures after the treatments. The results indicated that the increment of the initial glutaraldehyde concentration induced an increase of the enzyme loading on the membrane surfaces but a decrease in the activity of the immobilized enzyme. Under an optimum condition, the glutaraldehyde activated PVA-co-PE nanofibrous membrane reached the highest enzyme activity at 676.19 U/g of the membrane. The pH tolerance, thermal and storage stability of the immobilized lipase were significantly improved. In addition, the immobilized lipase can be easily recovered and retained at 67% of its initial activity after 10 time uses. Therefore, the glutaraldehyde activated PVA-co-PE nanofibrous membrane is a promising solid support media for enzyme immobilization, and the immobilized enzymes could have broad biocatalytic applications. 相似文献
18.
Polypropylene (PP)–silicon dioxide (SiO2) compound microporous membranes were fabricated by a melt-stretching method. Although the permeability, porosity, and hydrophilicity values of the microporous membranes were found to be highest at an SiO2 content of 2 wt %, the heat resistance of the membranes was relatively low. To improve the heat resistance of the microporous membranes, a macromolecular coupling agent, PP-g-poly(α-methyl styrene-co-glycidyl methacrylate-co-γ-methacryloxypropyl trimethoxy silane) (PAGK), was introduced into the membrane. In the PP–PP-g-PAGK–SiO2 composite systems, the content of SiO2 was controlled at 2 wt %, and the proportion of PP-g-PAGK was varied. With increasing PP-g-PAGK content to 0.6%, the Gurley value decreased from 250 to 239 s, and the porosity increased from 50.8 to 51.6%. The hydrophilicity of the microporous membranes increased with the incorporation of PP-g-PAGK, and their water vapor transmission rate reached a maximum of 3360 g m−2/24 h at a PP-g-PAGK content of 0.6%. The heat resistance of the PP–PP-g-PAGK–SiO2 compound microporous membranes was slightly higher than that of the pure PP microporous membrane. Additionally, the cycle performance of a cell assembled with the PP–PP-g-PAGK–SiO2 membrane was better than that constructed with the pure PP membrane. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47937. 相似文献
19.
Guangqun Zhai 《应用聚合物科学杂志》2006,100(5):4089-4097
The copolymer poly(vinylidene fluoride)‐graft‐poly(4‐vinylpyridine) (PVDF‐g‐P4VP) was prepared through the graft copolymerization of poly(vinylidene fluoride) with 4‐vinylpyridine. Through the blending of the PVDF‐g‐P4VP copolymer with poly(N‐isopropylacrylamide) (PNIPAm) in an N‐methyl‐2‐pyrrolidone solution, PVDF‐g‐P4VP/PNIPAm membranes were fabricated by phase inversion in aqueous media. Elemental analyses indicated that the blend concentration of PNIPAm in the blend membranes increased with an increase in the blend ratio used in the casting solution. Scanning electron microscopy revealed that the membrane surface tended to corrugate at a low PNIPAm concentration and transformed into a smooth morphology at a high PNIPAm concentration. The surface morphology and pore size distribution of the microfiltration membranes could be regulated by the blend concentration of the casting solution, temperature, pH, and ionic strength of the coagulation bath. X‐ray photoelectron spectroscopy revealed a significant enrichment of PNIPAm on the membrane surface. The flux of aqueous solutions through the blend membranes exhibited a pH‐ and temperature‐dependent behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4089–4097, 2006 相似文献
20.
The nanostructured Si@S-doped C (Si/C) hybrid is synthesized via a mild hydrothermal process of glucose and the simultaneous polymerization of 3,4-ethylenedioxythiophene and poly(sodium-4-styrene sulfonate) on the surface of nano-Si powders, then followed by a calcination process. A new water soluble polymer of poly(vinyl alcohol) (PVA) grafted with poly(acrylic acid) (PAA) is synthesized via a free-radical polymerization of acrylic acid (AA) in a 1:1 weight ratio in PVA water solution. The Si/C anode using PVA-g-PAA binder, exhibits improved lithium storage properties and cycling stability than that of the parallel electrode with carboxymethyl cellulose binder, which exhibits an initial coulombic efficiency (82.0%), even a reversible capacity of 487 mAh g−1 after 300 cycles with 81.2% capacity retention at 0.4 A g−1. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48764. 相似文献