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1.
A novel hydrophilic nanocomposite additive(TiO2-g-PNIPAAm) was synthesized by the surface modification of titanium dioxide(TiO2) with N-isopropylacrylamide(NIPAAm) via "graft-from" technique. And the nanocomposite membrane of poly(vinylidene fluoride)(PVDF)/TiO2-g-PNIPAAm was fabricated by wet phase inversion. The graft degree was obtained by thermo-gravimetric analysis(TGA). Fourier transform infrared attenuated reflection spectroscopy(FTIR-ATR) and X-ray photoelectronic spectroscopy(XPS) characterization results suggested that TiO2-g-PNIPAAm nanoparticles segregated on membrane surface during the phase separation process. Scanning electron microscopy(SEM) was conducted to investigate the surface and cross-section of the modified membranes. The water contact angle measurements confirmed that TiO2-g-PNIPAAm nanoparticles endowed PVDF membranes better hydrophlilicity and thermo-responsive properties compared with those of the pristine PVDF membrane. The water contact angle decreased from 92.8° of the PVDF membrane to 61.2° of the nanocompostie membrane. Bovine serum albumin(BSA) static and dynamic adsorption experiments suggested that excellent antifouling properties of membranes was acquired after adding TiO2-gPNIPAAm. The maximum BSA adsorption at 40 °C was about 3 times than that at 23 °C. The permeation experiments indicated the water flux recover ratio and BSA rejection ratio were improved at different temperatures.  相似文献   

2.
Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm−2h−1 and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability.  相似文献   

3.
《中国化学快报》2022,33(8):3859-3864
Superwetting membranes have emerged as promising materials for the efficient treatment of oily wastewater. Typically, superwetting membranes can be developed by ingeniously chemical modification and topographical structuration of microporous membranes. Herein, we report the hierarchical assembly of metal-phenolic-polyplex coating to manipulate membrane surface superwettability by integrating metal-phenolic (FeIII-tannic acid (TA)) assembly with polyplex (tannic acid-polyethylenimine (PEI)) assembly. The proposed Fe-TA-PEI coating can be deposited on microporous membrane via simply dipping into FeIII-TA-PEI co-assembly solution. Based on the catechol chemistry, the coordination complexation of FeIII and TA develops metal-phenolic networks to provide hydrophilic chemistries, and the electrostatic complexation of TA and PEI generates nanoconjugates to impart hierarchical architectures. Benefiting from the synergy of hydrophilic chemistries and hierarchical architectures, the resulting PVDF/Fe-TA-PEI membrane exhibits excellent superhydrophilicity (~0°), underwater superoleophobicity (~150°) and superior anti-oil-adhesion capability. The superhydrophilicity of PVDF/Fe-TA-PEI membrane greatly promotes membrane permeability, featuring water fluxes up to 5860 L m?2 h?1. The underwater superoleophobicity of PVDF/Fe-TA-PEI membrane promises potential flux (3393 L m?2 h?1), high separation efficiency (99.3%) and desirable antifouling capability for oil-in-water emulsion separation. Thus, we highlight the reported hierarchical metal-phenolic-polyplex assembly as a straightforward and effective strategy that enables the synchronous modulation of surface chemistry and topography toward superwetting membranes for promising high-flux and antifouling oil-water separation.  相似文献   

4.
Min Shang  Baoli Shi 《Chemical Papers》2018,72(12):3159-3167
Cellulose acetate (CA) forward osmosis (FO) membranes were prepared via a phase inversion process. CA was used as membrane material for FO. Acetone and 1,4-dioxane were employed as solvent. Polyvinylpyrrolidone (PVP), maleic acid, and methanol were applied as additives. An orthogonal experiment was performed to optimize the ratio of every component in the casting solution. The membrane with best performance was selected to concentrate an anthocyanin solution. Saturated sucrose solution (about 60°Brix) was fit for using as draw solution in the concentration experiment. Water flux, porosity, and rejection rate were measured to evaluate the membrane properties. Reverse water rinsing was used in cleaning membrane that was fouled by anthocyanin solution. Results showed that under membrane thickness of 100 μm, coagulation temperature at room temperature, and evaporation time of 30 s, the optimum components in casting solution were 13% CA, 45% 1,4-dioxane, 31% acetone, 2% maleic acid, 3% PVP, and 6% methanol. In the concentration experiment, the prepared FO membrane showed water flux of 2.04 L m?2 h?1 and rejection rate of 98.61%. In the membrane cleaning experiment, the water flux of the FO membrane recovered 87.51% after rinsing for 1 h. The prepared membranes and previously published membranes were compared which showed the prepared membrane could significantly improve the rejection rate for anthocyanin solution.  相似文献   

5.
Although water supplies are prominently dependent on desalination technology, desalination plant facing severe issues of discharged brine concentrate. Membrane distillation crystallization is an emerging synergistic technology that resolves the issue of brine concentrate by recovering clean water and value-added minerals simultaneously. In the present study, properties of polyvinylidene fluoride (PVDF) membrane were modified by incorporation of exfoliated fillers of hexagonal boron nitride and polyethylene glycol. The changes in morphology, surface roughness, hydrophobicity, thermal stability, and chemical composition of the prepared membranes were evaluated by scanning electron microscopy, atomic force microscopy, contact angle, thermogravimetric analysis, Fourier-transform infrared spectroscopy, respectively. Membrane distillation crystallization experiments were conducted to observe the effect of modified membranes on the permeate flux and salts recovery at different feed temperatures. The results showed a significant improvement in the permeate flux with modified membranes compared with pure PVDF membrane. It was found that hexagonal boron nitride/polyethylene glycol200 incorporated PVDF membrane gave the higher permeate flux (3.41 kg/m2 h for K2SO4 and 2.62 kg/m2 h for KNO3) at a temperature of 80 °C along with higher salts recovery than pure PVDF membranes. A 100 h long run test was conducted on modified membranes, which showed consistency in permeate flux with a marginal increase in conductivity.  相似文献   

6.
徐又一 《高分子科学》2013,31(7):994-1001
A novel method for the surface modification of PVDF porous membranes was introduced. Styrene-(N-(4-hydroxyphenyl) maleimide) alternating copolymer SHMI-Br was blended with PVDF to fabricate SHMI-Br/PVDF membranes. The C-Br bond on the SHMI-Br/PVDF membrane was served as initial site of ATRP, and P(PEGMA) brush was grafted on the PVDF membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR/FTIR) was used to prove the P(PEGMA) brushes were successfully grafted onto the SHMI-Br/PVDF membrane surface. Introduction of P(PEGMA) brushes on the PVDF membrane surface enhanced the hydrophilicity effectively. When the PEGMA degree of grafting was 16.7 wt%, the initial contact angle of PVDF membrane decreased from 98° to 42°. The anti-fouling ability of PVDF membrane was improved significantly after P(PEGMA) brush was grafted. Taking the PEGMA degree of grafting 16.7 wt% as an example, the flux of protein solution was about 151.21 L/(m2 h) when the pH value of the BSA solution was 4.9. As the pH value was increased to 7.4, the flux was changed to 180.06 L/(m2 h). However, the protein solution flux of membrane M3 (PEGMA: 0 wt%) was only 73.84 L/(m2 h) and 113.52 L/(m2 h) at pH 4.9 and 7.4, respectively.  相似文献   

7.
New membrane distillation configurations and a new membrane module were investigated to improve water desalination. The performances of three hydrophobic microporous membranes were evaluated under vacuum enhanced direct contact membrane distillation (DCMD) with a turbulent flow regime and with a feed water temperature of only 40 °C. The new configurations provide reduced temperature polarization effects due to better mixing and increased mass transport of water due to higher permeability through the membrane and due to a total pressure gradient across the membrane. Comparison with previously reported results in the literature reveals that mass transport of water vapors is substantially improved with the new approach. The performance of the new configuration was investigated with both NaCl and synthetic sea salt feed solutions. Salt rejection was greater than 99.9% in almost all cases. Salt concentrations in the feed stream had only a minor effect on water flux. The economic aspects of the enhanced DCMD process are briefly discussed and comparisons are made with the reverse osmosis (RO) process for desalination.  相似文献   

8.
Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10?6 S cm?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (Tg) of the ion conductive phase by ~5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10?6 S cm?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the Tg of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007  相似文献   

9.
Herein, we study the preparation and characterization of a new kind of proton exchange membrane. In the proton‐conducting membrane of poly(vinylidene fluoride) (PVDF)/poly(ethylene oxide) (PEO)/dodecyl benzenesulfonic acid (DBS‐H), we use PEO as “proton solvent” due to its flexible molecular chain. Moreover, the electronegativity of the O atom on PEO may be used to attract protons under anhydrous conditions. The membranes are thermally stable up to 200 °C with less than 3 % mass loss. At 150 °C, without extra humidification, the proton conductivity of 60 % PVDF/22 % PEO/18 % DBS‐H membrane is approximately 10 ?3 S cm?1.  相似文献   

10.
Modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid was carried out in order to prepare thermally stable polymers as membrane materials having increased hydrophilicity and potentially improved fouling-resistance. The sulfonated poly(phthalazinone ether sulfone ketone)s (SPPESK) were fabricated into ultrafiltration (UF) and nanofiltration (NF) asymmetric membranes. The effects of SPPESK concentration and the type and concentration of additives in the casting solution on membrane permeation flux and rejection were evaluated by using an orthogonal array experimental design in the separation of polyethyleneglycol (PEG12000 and PEG2000) and Clayton Yellow (CY, MW 695). One UF membrane formulation type had a 98% rejection rate for PEG12000 and a high pure water flux of 867 kg m−2 h−1. All the NF membranes made in the present study had rejections of ≥96%, and one had a high water flux of 160 kg m−2 h−1. Several of the NF membrane formulation types had ∼90% rejection for CY. When the membranes were operated at higher temperatures (80°C), the rejection rates declined slightly and pure water flux was increased more than two-fold. Rejection and flux values returned to previous values when the membranes were operated at room temperature again. Mono- and divalent salt rejections and fluxes were studied on an additional NF membrane set.  相似文献   

11.
A facile preparation strategy was proposed for preparation of compact zeolite LTA membranes on polyethyleneimine(PEI) modified substrates without seeding.Through the functionalization of substrates by using PEI,compact LTA membranes can be formed on various kinds of substrates.A well-intergrown and phase-pure LTA membrane with a thickness of about 3.0 μm is successfully prepared on the a-Al_2 O_3 disk after crystallization for 24 h at 60℃.Besides LTA membrane,wellintergrown zeolite FAU membranes can also be formed on PEI-modified a-Al_2 O_3 substrates,suggesting the universality of this strategy.The zeolite LTA membranes synthesized on PEI-modified a-Al_2 O_3 tubes we re evaluated fo r the separation of alcohols/water mixture through pervaporation.The as-synthesized zeolite LTA membranes display high pervaporation performances.For the separation of 10 wt% isopropanol/water solution at 90℃,a high separation factor of44991 and a water flux of 1.73 kg m ~2 h ~1 are achieved.  相似文献   

12.
Metal–organic frameworks (MOFs) are made up of metal centers and organic binders with larger surface area and distinct pore structures. Particularly significant advancement in MOF membranes has been achieved in three different directions: preparation of MOF membranes with larger surface area, improving the membrane performance by surface modification, and its usage with added features. However, its significance has not been completely known and concluded yet. MOF membranes are used in a variety of membrane-based separation like gas permeation, nanofiltration, pervaporation, membrane distillation, etc. This research aims to synthesize MOFs (ZIF-8 and ZIF-67) and MOF membranes (ZIF-8/PVDF and ZIF-67/PVDF) and used them in the pervaporative separation of the methanol/water mixture. MOFs and MOF membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetry analysis. Methanol/water mixtures were be used to study the performance of the prepared membranes. A study on the process parameters such as temperature (40, 45, 50, and 55°C), feed pressure (4, 8, 12, and 16 psi), and feed composition (10%, 20%, 30%, and 40% of water) was carried out to examine the effect of each process parameters for pure membrane. In contrast, Taguchi screening design was used to screen the most influential process variable. The optimized conditions based on Taguchi screening method were 55°C, 12 psi, and 40 %vol of water in feed. The obtained total flux of 425 L/m2h was observed for M3 membrane. As feed temperature increased, the total flux of all three membranes was increased.  相似文献   

13.
Calcium alginate-chitosan (CA/CS) blended membranes were prepared and crosslinked with maleic anhydride (MA) for the pervaporation (PV) separation of ethylene glycol (EG)/water mixtures at 30°C. The structure and properties of blend membranes were studied with the aid of FTIR, XRD, TGA, and SEM. The effect of experimental parameters such as feed composition, membrane thickness, and permeate pressure on separation performance of the MA crosslinked membranes were determined in terms of flux, selectivity, and pervaporation separation index. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the blend membranes in pure, as well as in binary mixtures. The experimental results suggested that the crosslinked membrane (M-CA/CS) exhibited a good selectivity of 302 at a normalized flux of 0.38 kg.m? 2.h? 1.10 μ m at 30°C for 96.88 wt% EG aqueous solution.  相似文献   

14.
Multi-layer PDMS/PVDF composite membrane with an alternative PDMS/PVDF/non-woven-fiber/PVDF/PDMS configuration was prepared in this paper. The porous PVDF substrate was obtained by casting PVDF solution on both sides of non-woven fiber with immersion precipitation phase inversion method. Polydimethylsiloxane (PDMS) was then cured by phenyltrimethoxylsilane (PTMOS) and coated onto the surface of porous PVDF substrate one layer by the other to obtain multi-layer PDMS/PVDF composite membrane. The multi-layer composite membrane was used for ethanol recovery from aqueous solution by pervaporation, and exhibited enhanced separation performance compared with one side PDMS/PVDF composite membranes, especially in the low ethanol concentration range. The maximum separation factor of multi-layer PDMS/PVDF composite membrane was obtained at 60 °C, and the total flux increased exponentially along with the increase of temperature. The composite membrane gave the best pervaporation performance with a separation factor of 15, permeation rate of 450 g/m2h with a 5 wt.% ethanol concentration at 60 °C.  相似文献   

15.
In this study, temperature-sensitive membranes were prepared by phase transition of the mixture of the temperature-sensitive poly(N-isopropylacrylamides) (PNIPAAM) microgels and poly(vinylidene fluoride). The results of Fourier transformed infrared spectrometer, X-ray photoelectron spectroscopy, elemental analysis, and scanning electron microscope photographs indicate that the PNIPAAM microgels are distributed more in the inner membrane than on the surface. The scanning electron microscope photographs reveal the blend membranes having porous surfaces with nanometer sizes and porous cross-sections with micrometer sizes. The addition of the PNIPAAM microgels is found to improve the porosity, the pore size, water flux, as well as to enhance the hydrophilicity and anti-fouling property of the blend membranes. The blend membrane shows temperature-sensitive permeability and protein rejection with the most dramatic change at around 32 °C which is the lower critical solution temperature of PNIPAAM, when water or bovine serum albumin solution flow through. Specifically, below 32 °C, the blend membrane shows a high protein rejection ratio which decreases with increasing temperature and a low water flux which increases with increasing temperature; above 32 °C, the blend membrane shows a low protein rejection ratio which decreases with increasing temperature and a high water flux which increases with increasing temperature.  相似文献   

16.
Thermally induced phase separation (TIPS) has been developed to prepare porous membranes. The porous structures are mainly dependent on diluents adopted in the TIPS process. We obtained two typical morphologies of poly(vinylidene fluoride) (PVDF) membranes using cyclohexanone (CO) and propylene carbonate (PC) as diluents, respectively. SEM observation displays that porous spherulites are formed from PVDF/CO system, whereas smooth particles result from PVDF/PC system. The TIPS processes of these two systems have been investigated in detail by optical microscope observation and temperature‐dependent FTIR combined with two‐dimensional infrared correlation analysis. Rapid crystallization of PVDF can be seen around 110 °C in the PVDF/CO system, which is consistent with the results of temperature‐dependent FTIR spectra. The spectral evolution indicates a transform of PVDF from amorphous to α‐phase after 110 °C. The νs(C?O) band at 1712 cm?1 narrows and the νs(C? F) band at 1188 cm?1 shifts to 1192 cm?1 before crystallization, which implies the destruction of interaction between PVDF and CO. In contrast, the PVDF/PC system shows slow crystallization with all‐trans conformation assigned to β‐phase and γ‐phase below 60 °C but no obvious change of polymer?diluent interaction. We propose two mechanisms for the different phase behaviors of PVDF/CO and PVDF/PC systems: a solid?liquid phase separation after destruction of polymer?diluent interaction in the former, and a liquid?liquid phase separation process coupled with rich‐phase crystallization in the later. This work may provide new insight into the relationship among morphologies, crystal forms, and phase separation processes, which will be helpful to adjust membrane structure. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1438–1447  相似文献   

17.
Alkaline fuel cells potentially offer improved conversion efficiency and the prospect of using non‐noble metal catalysts; however, low conductivity and fast degradation of anion exchange membranes (AEMs) prevent their widespread application. In this work, a series of novel composite AEMs were synthesized by incorporating guanidinium‐based polymers into a porous polytetrafluoroethylene (PTFE) film. The guanidinium‐based polymers were polymerized using a condensation process between a guanidinium salt and two different diamines so that the guanidinium cations were tethered to the polymer backbone to enhance both conductivity and durability. In addition, polymer crosslinking was conducted to further reinforce the mechanical strength of the membranes and interlock the guanidinium moieties to the porous PTFE. It was found that the ionic conductivity of the synthesized membrane reached up to approximately 80 mS cm?1 at 20°C in deionized water. These membranes also exhibited superior stability compared to commercial quaternary ammonium AEMs after being exposed in 5 M KOH solution at 55°C for 50 h. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

18.
The composite polymer electrolyte membranes were prepared from sulfonated poly (ether sulfone) (SPES), silicotungstic acid (STA) and fly ash (FA). Post sulfonation process was adopted to synthesize SPES using sulphuric and chlorosulfonic acid. The prepared electrolyte membranes were examined by water uptake capacity, swelling ratio, ion-exchange ability, proton conductivity, thermal stability and electrochemical performance for evaluating the pertinence of these membranes in fuel cell applications. As such the pristine membrane restricts with the proton conductivity of 0.042?S cm?1 at 30?°C and 0.060?S cm?1 at 90?°C while the polymer composite membrane, SP-STA-FA-10 reveals the maximum conductivity of 0.054?S cm?1 at 30?°C and 0.073?S cm?1 at 90?°C. It also exhibits good thermal stability than that of the pure membrane. The membrane electrode assemblies (MEAs) have been successfully developed from SPES as well as SP-STA-FA-10 membranes and their electrochemical performance were studied the wide range of current density. Herein, the composite membranes derived from SPES, STA and FA can be viable candidates for fuel cell applications.  相似文献   

19.
A silver nanoparticles-poly(carboxybetaine methacrylate)(AgNPs-PCBMA) nanocomposite was prepared on poly(vinylidene fluoride)(PVDF) membrane surface to improve its hydrophilicity and antifouling properties. Firstly, the PVDF membranes were grafted by PCBMA via physisorbed free radical grafting technique. Then Ag+ coordinated to the carbonyl group on PCBMA andsubsequently was reduced to silver nanoparticles. The hydrophilicity of the PVDF-gPCBMA/Ag membrane wasenhanced with the increasing fixed degree(FD) of AgNPs, and the original water contact angle of membrane was reduced to 33.97°. Additionally, water flux recovery ratio(FRR) andbovine serum albumin(BSA) rejection ratio of PVDF-g-PCBMA/AgNPs membrane wereimproved from 52% to 93.32% and 28.12% to 91.12%, respectively. Further, the PVDF-g-PCBMA/AgNPs membranes exhibited the more pronounced inhibition zone. The study demonstrated that compared with pure AgNPs or the PCBMA polymer brush, the synergistic effect of PCBMA and AgNPs made PVDF membranes havebetter hydrophilicity and anti-bacterialperformances.  相似文献   

20.
《先进技术聚合物》2018,29(1):254-262
Membrane technology has been successfully applied for the removal of dyes from wastewater in the textile industry. A novel poly(vinylidene fluoride) (PVDF) membrane was prepared via blending with different dosages of Ag‐TiO2‐APTES composite for dyeing waste water treatment in our study. And the effect of Ag‐TiO2‐APTES blended into the PVDF membrane was discussed, including the rejection rate of methylene blue (MB) dye, membrane morphology, surface hydrophilicity, antibacterial activity, and a certain photocatalytic self‐cleaning performance. X‐ray diffraction and Fourier transform infrared characterization confirmed that Ag‐TiO2 was functionalized by amount of hydroxyl group (−OH) and amino group (NH−), which provided by APTES. Contact angle measurement certified that the hydrophilicity of the membrane surface increased, with the contact angle decrease to 61.4° compared with 81.8° of original PVDF membrane. MB rejection rate was also increased to 90.1% after addition of Ag‐TiO2‐APTES, and the rejection of original membrane was only 74.3%. The morphologies of membranes were observed by scanning electron microscope, which indicated that Ag‐TiO2‐APTES had a good dispersion in membrane matrix and also improved the microstructure of membranes. Besides, UV irradiation experiments were performed on the composite films contaminated by MB, and the result showed that Ag‐TiO2‐APTES nanoparticle provided PVDF membrane with a certain photodegradation capacity under UV irradiation. Moreover, antibacterial activity of the composite membrane was also demonstrated through antibacterial experiment, Escherichia coli as the representative bacteria. Perhaps, this research may provide a new way for PVDF blending modification.  相似文献   

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