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1.
With the ever frequent of industrial organic solvent emissions and oil spillages, the development of high efficiency oil/water separation materials has attracted extensive attention. Here, PLA-based nanofiber membranes modified with metal oxides (SiO2, TiO2, Al2O3, and CeO2) are fabricated through blow spinning the mixed solution of polylactic acid (PLA) and metal oxide nanoparticles (NPs). Results shows that the addition of SiO2 NPs significantly increases the hydrophobicity of the membranes, while maintaining the excellent superoleophilicity. The PLA/SiO2 nanofiber membranes demonstrate a higher separation performance than pure PLA, PLA/TiO2, PLA/Al2O3, and PLA/CeO2 nanofiber membranes with high separation efficiency (~100%) and permeation flux (17,800 L m−2 h−1 for n-heptane), as well as prominent oil adsorption capacity (19.9 g/g for n-hexane). The successful fabrication of metal oxides modified PLA nanofiber membranes with high separation and adsorption ability, and excellent durability hold great application potential in the field of oily wastewater treatment.  相似文献   

2.
Coaxial electrostatic spinning (co-electrostatic spinning) technology has greatly expanded the versatility of the preparation of core–shell polymer nanofibers and has found a wide range of applications in the environmental and biological fields. Here we present a method for the preparation of coaxial nanofibers using polyacrylonitrile (PAN) and polyurethane (PU) as raw materials. It was found that the tensile strength ranges from 2.14 to 4.07 MPa with the increasing spinning speed of the nucleated PU layer, and the elongation at break was up to 95.09% for M6:4, which was three times higher than that of the original MPAN (30.54%), and the toughness of the nanofiber film was also significantly improved. Finally, the oil/water separation capacity of the coaxial nanofiber membrane was investigated, and the results showed that the separation fluxes for various oil compounds ranged from 2380.18 to 3130.17 L·m−2·h−1, with separation efficiencies above 99%. This study not only investigates the effect of different flow rates of core (PU)/shell (PAN) on the performance of coaxial electrostatic spun nanofiber membranes, but also provides a new insight into the coaxial electrostatic spinning process.  相似文献   

3.
Thiol-functionalized mesoporous poly (vinyl alcohol)/SiO2 composite nanofiber membranes and pure PVA nanofiber membranes were synthesized by electrospinning. The results of Fourier transform infrared (FTIR) indicated that the PVA/SiO2 composite nanofibers were functionalized by mercapto groups via the hydrolysis polycondensation. The surface areas of the PVA/SiO2 composite nanofiber membranes were >290 m2/g. The surface areas, pore diameters and pore volumes of PVA/SiO2 composite nanofibers decreased as the PVA content increased. The adsorption capacities of the thiol-functionalized mesoporous PVA/SiO2 composite nanofiber membranes were greater than the pure PVA nanofiber membranes. The largest adsorption capacity was 489.12 mg/g at 303 K. The mesoporous PVA/SiO2 composite nanofiber membranes exhibited higher Cu2+ ion adsorption capacity than other reported nanofiber membranes. Furthermore, the adsorption capacity of the PVA/SiO2 composite nanofiber membranes was maintained through six recycling processes. Consequently, these membranes can be promising materials for removing, and recovering, heavy metal ions in water.  相似文献   

4.
Design and preparation of membranes with ultrahigh separation performance and antifouling property for oil-in-water (O/W) emulsions remains challenging. In this study, a high flux mullite/TiO2 ceramic composite membrane was prepared via multi-precipitation of TiO2 on a whisker mullite hollow fiber support synthesized by combining phase inversion and high-temperature sintering techniques. The results showed that the generated whisker mullite structure improved the permeation flux, and the micro-nano structured TiO2 functional layer endowed the membrane surface with superhydrophility and stability. The retention of the optimal composite membrane (M20T13) that was soaked in the titanium solution 20 times for 13 min each time for the O/W emulsions like n-hexane, toluene and engine oil maintained over 98 %, and the flux after 6 h filtration was 668.34 L·m−2·h−1, 487.25 L·m−2·h−1 and 258.66 L·m−2·h−1, respectively, much higher than that of the optimal substrate (F3A1, mass ratio of fly ash: Al2O3 = 3:1). Moreover, the flux recovery rate of M20T13 was much higher than that of F3A1 after chemical backwashing. This work manifests great potential in O/W treatment fields.  相似文献   

5.
Improving the electrochemical properties of membranes in lithium-ion batteries (LIBs) is very important. Many attempts have been made to optimize ionic conductivity of membranes. The aim of this study was fabricating composite nanofiber membranes of poly(vinylidene fluoride) (PVDF), containing titanium dioxide (TiO2) and graphene oxide (GO) nanoparticles to use in LIBs as separators. The morphology, crystallinity, porosity, pore size, electrolyte uptake, ionic conductivity, and electrochemical stability of the membranes were investigated using scanning electron microscopy, wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and linear sweep voltammetry. The electrolyte uptake and ionic conductivity of the PVDF/TiO2/GO composite nanofiber membranes containing 2 wt % GO were 494% and 4.87 mS cm−1, respectively, which were higher than those of the other fabricated membranes as well as the commercial Celgard membrane. This could be attributed to the increased porosity, larger surface area, and higher amorphous regions of the PVDF/TiO2/GO composite nanofiber membranes as a result of the synergistic effects of the nanoparticles. In this work, suitable optimized membranes with greater electrochemical stability compared with the other membranes were presented. Also, it was demonstrated that the incorporation of the TiO2 and GO nanoparticles into the PVDF nanofiber membranes led to a porous structure where the electrolyte uptake enhanced. These properties made these membranes promising candidates for being used as separators in LIBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48775.  相似文献   

6.
Oil–water separation has attracted research interest due to the damages of oily wastewater caused to the environment and human beings. Electrospun fiber membrane has high oil–water separation performance. A nanofibers membrane with multi-stage roughness was prepared by electrospinning using poly(vinylidene fluoride)(PVDF)-silica blend solution as raw material. The result shows that the water contact angle (WCA) of the nanofibers membrane was promoted from 138.5 ± 1° to 150.0 ± 1.5° when the SiO2 content was increased from 0 to 3 wt%. The nanofibers membranes exhibited excellent separation efficiency (99 ± 0.1%) under gravity drive, with high separation flux of 1857 ± 101 L·m−2·h−1. More importantly, the obtained PVDF-SiO2 nanofibers membranes showed excellent multi-cycle performance and stable chemical resistance, which would make them great advantages for the practical application of oil–water separation.  相似文献   

7.
The high glycerol miscibility in water needs more efficient processes to decrease the cost of dehydration. Water stable poly(vinyl alcohol) based membranes cross-linked with 15% w/w of maleic acid were used for dehydrating glycerol-water mixtures using pervaporation (PV). The membranes were characterized using water contact angle, profilometry, Fourier transformed infrared spectroscopy-attenuated total reflectance, x-ray photoelectron spectroscopy, water stability, swelling tests, and PV. Membranes were treated using dry methods with vacuum ultraviolet (VUV; 162 nm) or ultraviolet (UV)-C (254 nm) radiation and exposed to O2 or acrylic acid vapors, respectively. The VUV and UV-C treatments improve PV performances, increasing the water separation selectivity more than 4 and 8.5 times, respectively. UV-C treatments exhibit a water flux (kg m−2 h−1), selectivity and PSI (kg m−2 h−1) of 0.3, 250, and 87.4 respectively. Highly hydrophilic functional groups grafted onto the surface of the membranes after irradiation favor the selective transfer of water through the membrane. Overall, the VUV or UV-C membrane treatments show great PV prospect in glycerol dehydration.  相似文献   

8.
The wetting resistance of poly(vinylidene fluoride) (PVDF) membrane is a critical factor which determines the carbon dioxide (CO2) absorption performance of the gas–liquid membrane contactors. In this study, the composite PVDF–polytetrafluoroethylene (PTFE) hollow fiber membranes were fabricated through dry-jet wet phase-inversion method by dispersing PTFE nanoparticles into PVDF solution and adopting phosphoric acid as nonsolvent additive. Compared with the PVDF membrane, the composite membranes presented higher CO2 absorption flux due to their higher effective surface porosity and surface hydrophobicity. The composite membrane with addition of 5 wt % PTFE in the dope gained the optimum CO2 absorption flux of 9.84 × 10−4 and 2.02 × 10−3 mol m−2 s−1 at an inlet gas (CO2/N2 = 19/81, v/v) flow rate of 100 mL min−1 by using distilled water and aqueous diethanolamine solution, respectively. Moreover, the 5% PTFE membrane showed better long-term stability than the PVDF membrane regardless of different types of absorbent, indicating that polymer blending demonstrates great potential for gas separation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47767.  相似文献   

9.
PFSA-TiO2(or Al2O3)-PVA/PVA/PAN difunctional hollow fiber composite membranes with separation performance and catalytic activity have been prepared by dip-coating method. The good separation performance was brought about by the glutaraldehyde (GA) surface cross-linked PVA/PAN composite membrane, and the good catalytic activity of the membrane was achieved by the perfluorosulphonic acid (PFSA) used. The difunctional hollow fiber membranes were characterized by XRD, TGA, EDX, SEM, and FTIR. The separation performance was measured by dehydration of azeotropic top product of ethanol-acetic acid esterification, and the catalytic activity was obtained by investigating the esterification of ethanol and acetic acid. The FTIR spectra and the morphologies of difunctional hollow fiber composite membranes were similar for samples prior to esterification and post-esterification with ethanol and acetic acid for 24?h. Difunctional hollow fiber composite membranes with 2% PFSA, 8% TiO2 (named as DM-T1), and 2% PFSA, 8% Al2O3 (named as DM-A1) (all by weights) showed the best catalytic activity. They displayed fluxes of 165 and 173?g/m2?h, separation factors of water to ethanol of 279 and 161, PFSA contents in difunctional hollow fiber composite membrane of 3.2 and 2.4%, the ratios of PFSA to feed solution (acetic acid?Cethanol) of 0.031 and 0.023%, and the equilibrium conversion of ethanol at 53.5 and 57.6%, in the given order for TiO2 and Al2O3 containing samples.  相似文献   

10.
Carbonic anhydrase (CA) catalyzing CO2 hydration has an important application in carbon capture, and its immobilization is very significant. Here, CA was covalently linked by glutaraldehyde (GA) to the surface of poly(vinylidene fluoride) (PVDF) and polyethylene (PE) membranes, which were previously modified via a simple codeposition of polyethyleneimine (PEI) and dopamine (DA). The effects of the modification conditions were investigated, and the membranes were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The immobilization process was optimized, and the catalytic properties of immobilized CA were studied. The results show that the optimal mass ratio of PEI and DA was 1:1 and the deposition time was 10–12 h, at which the surface amino group density could reach 1.278 × 10−7 and 1.397 × 10−7 mol/cm2 for PVDF and PE, respectively. For enzyme immobilization, the optimal CA and GA concentrations were 0.2 mg/mL and 0.1 wt %, and a maximum activity recovery of about 53% and 76% could be achieved for PVDF-attached CA and PE-attached CA, respectively. Their Km values were 10.62 mM and 8.6 mM, and the corresponding Kcat/Km values were 132.2 M−1 s−1 and 312.9 M−1 s−1. After immobilization, the storage stability and reusability of CA were much improved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47784.  相似文献   

11.
Fine-tuned, molecular-composite, organosilica membranes were fabricated via the co-condensation of organosilica precursors bis(triethoxysilyl)acetylene (BTESA) and bis(triethoxysilyl)benzene (BTESB). Fourier transform infrared and UV–vis spectra confirmed the co-condensation behaviors of BTESA and BTESB. The evolution of the network structure indicated that the incorporated BTESB decreased the membrane pore size, which was determined by a modified gas translation model according to the steric effect of the phenyl groups. The incorporation of BTESB to BTESA finely tuned the membrane structure and endowed the resultant composite membrane with improved separation properties. The BTESAB 9:1 membrane (molar ratio of BTESA/BTESB was 9:1) exhibited high C3H6 permeance at 4.5 × 10−8 mol m−2 s−1 Pa−1 and a C3H6/C3H8 permeance ratio of 33 at 50°C. One of the most important developments of this study involved clearly defining the relationship between membrane pore size and C3H6/C3H8 separation performance for organosilica membranes in single and binary separation systems.  相似文献   

12.
Nanofiltration composite membranes with high selectivity are one of the most critical cores in water treatment, and regulating the surface charge and pore structure of active separation layers in thin film composite membranes is one of the most effective means to improve the selectivity of composite membranes. This article synthesized a novel monomer with positive charge and a rigid twisted Tröger's base structure (named TBDA-SO3), which was manipulated to improve the microporous structure and surface charge of the composite membrane. By interfacial polymerization, TBDA-SO3, and piperazine were co-reacted with trimesoyl chloride to successfully prepare positively charged, highly selective, and strongly microporous polyamide composite nanofiltration membranes. The best-performing composite nanofiltration membrane in this article has a permeability similar to that of the control group's poly(piperazine amide) (PPA) membrane (pure water flux, 7.8 L m−2 h−1 bar−1), but has excellent divalent cation selectivity (52.57), which is 4.4 times that of the control group's PPA membrane.  相似文献   

13.
Metal–organic framework (MOF) membranes are promising for efficient separation applications. However, the uncontrollable pathways at atomic level impede the further development of these membranes for molecular separation. Herein we show that vapor linker exchange can induce partial amorphization of MOF membranes and then reduce their transport pathways for precisely molecular sieving. Through exchanging MOF linkers by incoming ones with similar topology but higher acidity, the resulted metal-linker bonds with lower strength cause the transformation of MOF membranes from order to disorder/amorphous. The linker exchange and partial amorphization can narrow intrinsic apertures and conglutinate grain boundary/crack defects of membranes. Because of the formation of ultra-microporous amorphous phase, the MOF composite membrane shows competitive H2/CO2 selectivity up to 2400, which is about two orders of magnitude higher than that of conventional MOF membranes, accompanied by high H2 permeance of 13.4 × 10−8 mol m−2 s−1 Pa−1 and good reproducibility and stability.  相似文献   

14.
In this study, polyacrylonitrile/cellulose acetate (PAN/CA) composite nanofiber membranes with different boehmite contents are prepared by electrospinning. The physical and electrochemical properties of the composite nanofiber membrane as a separator in lithium batteries are investigated. In contrast to commercial polypropylene membrane (PP), the nanocomposite fiber membrane has a 3D network structure, higher porosity, higher thermal stability, higher electrolyte absorptivity, higher ionic conductivity, and better cycling performance. The PAN/CA composite membrane with 12 wt% boehmite has the highest ionic conductivity (1.694 mS cm−1); the specific discharge capacity is 160 mAh g−1 at 0.2 C discharge density and the highest capacity retention rate is 99.3% after 100 cycles. The cycle rate at 2 C has a higher capacity retention rate (88.75%). These results indicate that the PAN/CA/AlOOH composite nanofiber membrane can be expected to replace the commercial polyolefin membrane and behave as a high-performance separator for lithium-ion batteries.  相似文献   

15.
Using Na+ form of perfluorosulfonic acid (PFSA) and poly(vinyl alcohol) (PVA) as coating materials, polysulfone (PSf) hollow fiber ultrafiltration membrane as a substrate membrane, PFSA‐PVA/PSf hollow fiber composite membrane was fabricated by dip‐coating method. The membranes were post‐treated by two methods of heat treatment and by both heat treatment and chemical crosslinking. Maleic anhydride (MAC) aqueous solution was used as chemical crosslinking agent using 0.5 wt % H2SO4 as a catalyst. PFSA‐PVA/PSf hollow fiber composite membranes were used for the pervaporation (PV) separation of isopropanol (IPA)/H2O mixture. Based on the experimental results, PFSA‐PVA/PSf hollow fiber composite membrane is suitable for the PV dehydration of IPA/H2O solution. With the increment of heat treatment temperature, the separation factor increased and the total permeation flux decreased. The addition of PVA in PFSA‐PVA coating solution was favorable for the improvement of the separation factor of the composite membranes post‐treated by heat treatment. Compared with the membranes by heat treatment, the separation factors of the composite membranes post‐treated by both heat treatment and chemical crosslinking were evidently improved and reached to be about 520 for 95/5 IPA/water. The membranes post‐treated by heat had some cracks which disappeared after chemical crosslinking for a proper time. Effects of feed temperature on PV performance had some differences for the membranes with different composition of coating layer. The composite membranes with the higher mass fraction of PVA in PFSA‐PVA coating solution were more sensitive to temperature. It was concluded that the proper preparation conditions for the composite membranes were as follows: firstly, heated at 160°C for 1 h, then chemical crosslinking at 40°C for 3 h in 4% MAC aqueous solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

16.
Pervaporation has great potential in the separation of many significant mixtures. However, excessive penetration of separation layer into the substrate pores enhances the transport resistance of solvent molecules, which impedes the development of pervaporation membrane. In this study, a facile floating-on-water (FOW) method was used to prepare poly(dimethylsiloxane) (PDMS)/polytetrafluoroethylene (PTFE) composite membranes. The formation of separation layer and preparation of composite membrane were step-by-step completed through this liquid–liquid interface induced method. The PDMS layer thickness could be precisely regulated from 0.5 to 8 μm. Moreover, the pore penetration could be controlled by optimizing pre-crosslinking density, crosslinking time on water and polymer solution volume. The obtained PDMS/PTFE composite membrane exhibited a high flux of 2016 g·m−2·h−1 with the separation factor of 12 when separating ethanol from a 5 wt% ethanol/water mixture. The performance of the membrane could be stable for over 200 h, exhibiting great potential in ethanol perm-selective pervaporation.  相似文献   

17.
Polysulfone (PSF) hollow fiber membranes were spun by phase‐inversion method from 29 wt % solids of 29 : 65 : 6 PSF/NMP/glycerol and 29 : 64 : 7 PSF/DMAc/glycol using 93.5 : 6.5 NMP/water and 94.5 : 5.5 DMAc/water as bore fluids, respectively, while the external coagulant was water. Polyvinyl alcohol/polysulfone (PVA/PSF) hollow fiber composite membranes were prepared after PSF hollow fiber membranes were coated using different PVA aqueous solutions, which were composed of PVA, fatty alcohol polyoxyethylene ether (AEO9), maleic acid (MAC), and water. Two coating methods (dip coating and vacuum coating) and different heat treatments were discussed. The effects of hollow fiber membrane treatment methods, membrane structures, ethanol solution temperatures, and MAC/PVA ratios on the pervaporation performance of 95 wt % ethanol/water solution were studied. Using the vacuum‐coating method, the suitable MAC/PVA ratio was 0.3 for the preparation of PVA/PSF hollow fiber composite membrane with the sponge‐like membrane structure. Its pervaporation performance was as follows: separation factor (α) was 185 while permeation flux (J) was 30g/m2·h at 50°C. Based on the experimental results, it was found that separation factor (α) of PVA/PSF composite membrane with single finger‐void membrane structure was higher than that with the sponge‐like membrane structure. Therefore, single finger‐void membrane structure as the supported membrane was more suitable than sponge‐like membrane structure for the preparation of PVA/PSF hollow fiber composite membrane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 247–254, 2005  相似文献   

18.
A novel composite membrane with a three‐layer structure has been prepared. The top layer is a thin dense film of chitosan crosslinked with glutaraldehyde, and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and the microporous layer, there is an intermolecular crosslinking layer. The performance data show that this is an excellent pervaporation membrane for alcohol dehydration and one‐stage separation is attainable for some alcohol/water mixtures such as ethanol/water and isopropanol/water systems, which has a good separation factor of 1410 and a good flux of 0.33 kg m−2 h−1 for the EtOH/H2O mixture, and 5000 and 0.43 kg m−2 h−1 for the i‐PrOH/H2O mixture using 90 wt % alcohol concentration at 70°C.Using 90 wt % methanol aqueous solution at 60°C, a flux of 0.17 kg m−2 h−1 and selectivity of 123 are also obtained. The structure and performance of the novel composite membrane varies with conditions of membrane preparation, such as hydrolysis degree of PAN membrane, content of crosslinking agent, and heat‐curing temperature. The results indicate that the separation factor and the permeation rate of this novel composite membrane increase with the increase of operating temperature. At the same time, the pervaporation properties can be adjusted by changing the structure of the top layer and the middle layer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 740–745, 2000  相似文献   

19.
In this study, a fabricated hydrophilic poly(vinyl alcohol‐co‐ethylene) (PVA‐co‐PE) nanofiber membrane was used as the middle support layer to prepare thin film composite (TFC) membranes for nanofiltration. The effects of the supporting nonwoven layer, grams per square meter (GSM) of nanofiber, reaction time, heat treatment, monomer concentration, operating pressure, and pH value on the separation performance of the TFC membranes were analyzed. These results show that the TFC membranes prepared with the PVA‐co‐PE nanofiber membrane can be used to filtrate different metal ions. For NaCl, Na2SO4, CaCl2, CuCl2, CuSO4, and methyl orange solutions, the rejection rates of the TFC membrane with nonwoven polyester as the supporting layer and a nanofiber GSM of 12.8 g/m2 are 87.9%, 93.4%, 92.0%, 93.1%, 95.8%, and 100%, respectively. This indicates the potential application of the PVA‐co‐PE nanofiber membrane in the preparation of nanofiltration and reverse‐osmosis TFC membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46261.  相似文献   

20.
The present study investigated the pervaporation performance of novel hydroxypropylated chitosan (HPCS) membranes to separate water from an aqueous alcohol solution. Hydroxypropylated chitosan was prepared from the reaction of chitosan and propylene oxide. The results show that the separation factor decreases and the flux increases with increasing of the substitution degree of the hydroxypropylated chitosan membrane. Crosslinking with glutaraldehyde or treatment with Cu2+ can improve the pervaporation performance of modified chitosan membrane grately. The performance data indicate that the crosslinking hydroxypropylated chitosan membrane treated with Cu2+ is an excellent pervaporation membrane for the separation of alcohol–water mixtures, and one-stage separation is attainable for some alcohol–water mixtures such as an n-propanol–water and an isopropanol–water system, which has a good separation factor of 220 for the n-PrOH/water system and 240 for the i-PrOH/water system using 85 wt % alcohol concentration at 60°C. The flux for both cases is around 0.5 kg m−2 h−1. At the same time, the structure of the chemically modified chitosan membranes and their separation characteristics for aqueous alcohol solutions are also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2035–2041, 1998  相似文献   

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