Super-hydrophilic electrospun PVDF/PVA-blended nanofiber membrane for microfiltration with ultrahigh water flux

This work provides a novel approach to improve not only water flux but also fouling resistance of Polyvinylidene fluoride (PVDF) membranes. PVDF/Poly(vinyl alcohol) (PVA)-blended nanofiber membranes were prepared via electrospinning method. The structure and performance of blended nanofiber membranes were characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), attenuated total reflection-Fourier-transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement, tensile mechanical measurement, and filtration experiments. These results indicate that PVA was uniformly blend in the PVDF matrix. This blended nanofiber membranes with the ridge-and-valley structure and bicontinuous phase exhibited the hydrophilic performance and super-wettability, which is reflected in a drop of water fully spread within 1.44 s. Filtration experiments showed that the blended nanofiber membranes have ultrahigh flux and low irreversible fouling ratio. In general, this work enhances the possibility of hydrophilic modification of hydrophobic PVDF membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48416.     

Creatinine adsorption capacity of electrospun polyacrylonitrile (PAN)‐zeolite nanofiber membranes for potential artificial kidney applications

Innovative dialysis membranes are needed for dialysis, which is the primary treatment for patients with end stage renal disease. In this study, we developed a polyacrylonitrile zeolite nanofiber composite membrane using an electrospinning process to adsorb uremic toxins through molecular sieve mechanism. Scanning electron microscope images revealed that the average diameter of the fiber fabricated with 10 wt % polyacrylonitrile was 673 nm and that of polyacrilonitirle‐zeolite membranes were 277?419 nm. The creatinine adsorption behavior of 500‐KOA (L), 720‐KOA (Farrierite), 840‐NHA (ZSM‐5), and 940‐HOA (Beta) zeolite powders were investigated. Among all the zeolites, 940‐HOA zeolites showed the best performance. The creatinine adsorption capacity of 940‐zeolite powders increased from 2234 µg/g in 50 µmol/L creatinine solution to 25423 µg/g in 625 µmol/L creatinine solution. The speed of adsorption was very quick; 0.025 g of 940‐zeolite powders can eliminate 91% of 2 µmol creatinine in 5 min. The zeolites incorporated inside the membrane had higher creatinine adsorption capacity than free zeolites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42418.     

Pervaporative aroma compounds recovery from lemon juice using poly(octyl methyl siloxane) membrane

BACKGROUND: In this research, a pervaporation process was used to recover volatile aroma compounds from lemon juice using a poly(octyl methyl siloxane) membrane. The majority of previous studies have been with binary model feed systems, while the results with actual feed mixtures did not always match those with model feeds. In order to successfully optimize the pervaporation process, it is essential to work with actual fruit juice. The influences of various operating parameters such as feed flow rate, feed temperature and permeate pressure on the permeate flux and selectivity were investigated. For this purpose, three compounds that make a significant contribution to lemon juice aroma, namely, α‐pinene, β‐pinene and limonene were studied. RESULTS: It was shown that decreasing the permeate pressure increased both permeation flux and enrichment factor, while an increase in feed temperature increased the water flux more significantly than the aroma compounds flux, resulting in lower enrichment factor. Also, the results indicated that feed flow rate had no significant effect on the performance of the process. CONCLUSION: The membrane used was found to be very selective towards α‐pinene, β‐pinene and limonene. It can be concluded that pervaporation is an attractive technology for the recovery of lemon aroma compounds as it yields good separation and operates under mild conditions. Copyright © 2010 Society of Chemical Industry     

Ce(IV)‐induced graft copolymerization of methacrylic acid on electrospun polysulphone nonwoven fiber membrane

Ce(IV)‐induced graft copolymerization of methacrylic acid (MAA) on polysulphone (PSU) surface is studied. After pretreatment either by formaldehyde solution or by air glow discharge plasma, the PSU fiber membrane was immersed in MAA solution with Ce(IV) and heated under 80°C under N₂ protection. The MAA was induced by the Ce(IV) redox initiation system to polymerize on the PSU fiber membrane surface. It was found that the pretreatment of the membrane is a very necessary condition for the graft copolymerization to obtain high graft degree. For both the formaldehyde and the air glow discharge plasma pretreated membrane, the graft degree increase with the reaction time. To study the reaction mechanism, control experiments were carried out. Membrane surfaces were characterized by ATR‐FTIR and XPS. The reaction mechanism of the graft copolymerization was discussed based on the experimental data. The effect of the graft copolymerization on the membrane's structure and water permeability was finally studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3835–3841, 2006     

A novel leukodepletion filter from electrospun poly(ethylene-vinyl alcohol) membranes and evaluation of its efficiency

The authors describe the fabrication and evaluation of a novel leukodepletion filter using novel poly(ethylene-vinyl alcohol) membranes through electrospinning. The membranes were biocompatible and nonhemolytic. A prototype of the filter was developed by stacking the membranes in a poly(methyl methacrylate) case. Upon whole blood filtration, the filter could achieve 100% leukodepletion while capturing 8% red blood cells and 91% platelets. The length of filtration through the developed filter was high when compared to that of marketed filter while overall performance of the filter was comparable to that of the marketed filter.     

膜分离技术在间歇式PP装置上的应用

应用有机蒸气膜分离技术,回收间歇式液相本体法聚丙烯生产过程中产生的不凝气中的丙烯,回收率达90％以上,岳阳石油化工总厂合成橡胶厂在原有工艺流程不变的情况下仅增加膜回收系统后,每天可以我回收2t丙烯,6个月已回收 丙烯370t,创经济效益110×10~2元,高于该系统的投资。     

多孔陶瓷膜烟气水分回收理论与模型研究

化石燃料燃烧烟气中含有大量水分和潜热,高湿度烟气的直接排放造成极大的资源浪费和环境问题。多孔陶瓷膜是目前烟气水热回收最有前景的技术之一,其水分回收热力学和动力学的定量描述是该技术发展和装置设计的关键所在。分析了水分在多孔陶瓷膜表面及内部传质机理,基于Kelvin理论建立了水分在陶瓷膜内毛细凝聚热力学模型,并选取典型烟气温/湿度条件,得出不同工况下陶瓷膜发生毛细凝聚的临界孔径、凝聚水量及工作孔体积占比;进而基于毛细凝聚的表面传质和孔道输运Hagen-Poiseuille方程建立了陶瓷膜水分传质动力学模型,对典型温/湿度工况下回收水通量进行了计算,结果表明,多孔陶瓷膜的毛细凝聚效应对烟气水分回收的优越性十分明显,其表面回水通量远远大于冷凝法的水通量,孔径越小,表面水通量越高,但及时将孔道内的液态水输运到陶瓷膜另一侧需要的压差也越大,本文计算条件下,膜孔径为20.0 nm的陶瓷膜较为适宜。     

多孔陶瓷膜烟气水分回收理论与模型研究

化石燃料燃烧烟气中含有大量水分和潜热,高湿度烟气的直接排放造成极大的资源浪费和环境问题。多孔陶瓷膜是目前烟气水热回收最有前景的技术之一,其水分回收热力学和动力学的定量描述是该技术发展和装置设计的关键所在。分析了水分在多孔陶瓷膜表面及内部传质机理,基于Kelvin理论建立了水分在陶瓷膜内毛细凝聚热力学模型,并选取典型烟气温/湿度条件,得出不同工况下陶瓷膜发生毛细凝聚的临界孔径、凝聚水量及工作孔体积占比;进而基于毛细凝聚的表面传质和孔道输运Hagen-Poiseuille方程建立了陶瓷膜水分传质动力学模型,对典型温/湿度工况下回收水通量进行了计算,结果表明,多孔陶瓷膜的毛细凝聚效应对烟气水分回收的优越性十分明显,其表面回水通量远远大于冷凝法的水通量,孔径越小,表面水通量越高,但及时将孔道内的液态水输运到陶瓷膜另一侧需要的压差也越大,本文计算条件下,膜孔径为20.0 nm的陶瓷膜较为适宜。     

A new gold(III)-aminoethyl imidazolium aurate salt as precursor for nanosized Au electrocatalysts

In this work the novel, robust, air- and moisture-stable gold(III)-aminoethyl imidazolium aurate salt [Cl₃AuNH₂(CH₂)₂ImMe][AuCl₄] (1) has been employed as precursor for the electrosynthesis of gold nanoparticles (AuNPs) onto ITO electrodes in 0.5 mol dm⁻³ H₂SO₄ aqueous solution without the use of additional additives and/or stabilizers. The electrode termed ILNH₂-Au_NPs200 prepared at a fixed electrodeposition time (t_d) of 200 s was characterized with AFM, SEM, XRD diffraction as well as cyclic voltammetry (CVs) and compared with an electrode in which the AuNPs have been electrodeposited from KAuCl₄ in the presence of KI as additive at the same t_d (Au_NPs200). The effect of the t_d (i.e. 50 s or 500 s; electrodes ILNH₂-Au_NPs50 and ILNH₂-Au_NPs500, respectively) was also investigated together with the electrocatalytic activity towards methanol oxidation in alkaline medium of all the prepared electrodes. The comparison with Au_NPs obtained with KI as additive shows that the presence of the amino-functionalized imidazolium moiety although not relevant in relation to the particle size, favours the metal electrodeposition process and plays an important role in the enhancement of the following parameters: (i) surface coverage (S.C.), (ii) electroactive particle coverage Φ_p %, (iii) electroactive surface area σ_red(exp)/σ_red(theor) and (iv) catalytic efficiency.     

Comparative performance analysis of electrospun TiO2 embedded poly(vinylidene fluoride) nanocomposite membrane for supercapacitors

For an efficient energy storage system, effective material is to be used. In the present work, novel poly(vinylidene fluoride)/titanium oxide (PVdF/TiO₂) composite membranes were developed using electrospinning technique, as separator for supercapacitors. Different weight percentages of TiO₂ nanoparticle (0, 5, 10, 15, and 20 wt%) were mixed with 20 wt% of PVdF in a 50:50 wt% of tetrahydrofuran and dimethylacetamide solvent. Various physical and electrochemical properties including fiber diameter, thermal stability, crystallinity, porosity, and electrolytic uptake were studied to identify the best membrane with optimum TiO₂ wt% exhibiting superior characteristics. SEM and TGA studies revealed that the developed PVdF/TiO₂ composite membrane with 10 wt% showed improved properties with a lower average diameter of about 66 ± 8 nm, enhanced thermal stability up to 513.15°C and higher porosity of 89%, respectively compared to other membranes. The crystallinity, ionic conductivity, and specific capacitance of the nonwoven separator membranes were determined using X-ray diffraction technique, electrolytic uptake, and charge–discharge studies, respectively. The present study revealed that the addition of TiO₂ nanoparticles improved the physical and thermochemical properties of the separator membrane substantially and PVdF/TiO₂ composite membrane with 10 wt% displayed superior performance compared to other membranes.     

A low pressure SWCNT-ENM sandwich membrane system for the removal of PPCPs from water

While carbon nanotubes are known as efficient adsorbents for removal of a number of contaminants from water, the possibility of their leaching into drinking water has prevented their application in water treatment. In this study, single walled carbon nanotubes (SWCNT) were sandwiched between two electrospun nanofibre membranes (ENM). The relatively small pore size of the ENM prevented the mechanically entangled nanotubes from passing through and contaminating the water. The performance of the SWCNT-ENM was evaluated in a lab-scale setup for the removal of PPCPs. For this purpose, a feed solution spiked with known concentrations of six PPCPs was passed through the membrane system. The target substances included acetaminophen (ACT), bezafibrate (BZF), iopromide (IOP), diclofenac (DCF), carbamazepine (CBZ), and sulphamethoxazole (SMX). The same test was also conducted using a single contaminant (ACT). Results demonstrated a decrease in the overall percent removal of PPCPs as feed flow rate and PPCP concentration increased. For multi-component feeds containing equal amounts of the aforementioned PPCPs, the overall percent removal decreased from 90.8% to 71.0% when increasing the feed concentration from 30 to 600 μg/L. Experiments using sandwiched powdered activated carbon (PAC) showed that the dynamic adsorption capacity of PPCPs by SWCNT-ENM was higher than that of PAC-ENM, and remained unaffected by the feed composition. In addition, the high porosity of this novel membrane allowed for flow of water with low resistance such that the trans-membrane pressure was found to be as low as 4 kPa at a pure water flux of 330 L/m²h.     

Eudragit E100/poly(ethylene oxide) electrospun fibers for DNA removal from aqueous solution

The development of new strategies for production of low-cost deoxyribonucleic acid (DNA) adsorbents based on electrospun fibers of block copolymers [Eudragit E-100/poly(ethylene oxide) (PEO)] is a promising way for fast retrieval of free of degradation double-stranded DNA chains from aqueous solution. The adsorption takes place through electrostatic interaction between DNA and oppositely charged electrospun fibers that provide high surface area for DNA adsorption. The adsorption capacity observed for electrospun fibers of Eudragit E100/PEO (considering as target molecules the salmon sperm DNA) was in order of 44.31 mg g⁻¹, following the Langmuir model in a typical adsorption at solid/liquid interface (pseudo-second-order model), that characterizes the electrospun fibers as promising templates for removal of biologic components and further use in molecular biology techniques, as DNA amplification by polymerase chain reaction. The reuse and integrity of membranes after long period of adsorption were tested, confirming the potential of material as adsorbent. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47479.     

A poly(ethylene terephthalate) nonwoven sandwiched electrospun polysulfonamide fibrous separator for rechargeable lithium ion batteries

A poly(ethylene terephthalate) nonwoven sandwiched electrospun polysulfonamide (PSA) fibrous separator was developed for application in lithium‐ion batteries (LIBs). The poly(ethylene terephthalate) nonwoven served as a mechanical support and the PSA layers provided the separators with nanoporous structures. This novel composite separator possessed better thermal stability and electrolyte wettability than commercial polypropylene separator and the sandwiched nonwoven endowed the separator with an improved mechanical strength (17.7 MPa) compared to the pure electrospun PSA separator. The cells assembled with this composite separator displayed excellent discharge capacity (122.0 mAh g^?1 after 100 cycles) and discharge C‐rate capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44907.     

Preparation and characterization of asymmetric ultrafiltration membrane for effective recovery of proteases from surimi wash water

The wash water generated from the surimi processing industry contains a large amount of proteases which are widely used in the food and biotechnology industries. Asymmetric polysulfone and polyethersulfone ultrafiltration (PSf-UF and PES-UF) membranes with three different polymer concentrations were screened for their abilities to recover proteases from surimi wash water. In-house fabricated membranes were prepared via a simple dry/wet phase inversion technique and were characterized in terms of permeability coefficient, membrane morphology and molecular weight cut-off (MWCO). The ability of the UF membranes to remove commercial proteases was tested at various pressures (up to 10 bars). The membrane with the best performance, 15 wt-% PSf-UF, was further tested with actual surimi wash water. The effect of the pH of the feed solution (4 to 8) in the pre-treatment stage was also evaluated to recover the highest amount of proteases. The highest retention of protease was 96% with a flux of 25.6 L/(m²·h) which was achieved with the 15 wt-% PSf-UF membrane.     

Emulsion liquid membrane for selective extraction of Bi(III)

Di(2-ethylhexyl)phosphoric acid was used as extractant of bismuth ions from nitrate medium by emulsion liquid membrane, with Triton X-100 as the biodegradable surfactant in n-pentanol bulk membrane. The novelties and innovative points of this work are the application of emulsion liquid membrane for selective and efficient extraction of bismuth ions as wel as the relevant optimization procedures. The extraction of bismuth ions was evaluated by the yield of extraction. The experimental parameters were evaluated and optimized, including the ratio of di(2-ethylhexyl)phosphoric acid mass concentration to Triton X-100 (1.0%:0.5%), nature of diluent (n-pentanol), nature and concentration of stripping solution (sulfuric acid, 0.5 mol·L?1), stirring speed (1800 r·min?1) and equilibrium time of extraction (20 min), initial feed solution of bismuth (350 mg·L?1) and the volume ratio of internal stripping phase to membrane phase (14). The experimental parameters of kinetic extraction reveal that the bismuth ions can be extracted by 100%.     

液膜法分离回收废水中锰（Ⅶ）工艺及其分离机理研究

采用N7301为流动载体,Span-80为表面活性剂,煤油为膜溶剂,以H2SO4为内相试剂的乳状液膜体系分离回收废水中的MnO~-_4。研究了迁移机理,确定了制乳、分离等最佳操作条件。结果表明,对于7-125mg/L低浓度的含锰废水,一次性分离可降至0.1mg/L以下,锰的回收率达99.8％。     

Simultaneous recovery of Cr(III) and Cr(VI) from the aqueous phase with ion-exchange membranes

The simultaneous recovery of trivalent and tetravalent chromium ions through charged ion-exchange membranes by using three detachable cells was tested at different current densities. The effect of mono- and divalent valence ions corresponding to trivalent and hexavalent chromium ions in the feed phase was investigated. The recovery factor values of chromium (III) and (VI) ion without current density were obtained and found that it was higher in the absence of binary monovalent and divalent ions, but increased with increasing current density and decreased in the presence of the binary mono- and divalent ions. The transport of both oxidation states of chromium ions through membranes was also correlated with the flux data.     

Ceramic membrane pretreatment of monosodium glutamate isoelectric supernatant to facilitate (NH4)2SO4 recovery by electrodialysis

BACKGROUND: The large output of monosodium glutamate in China has produced huge amounts of isoelectric supernatant containing 40–60 g L⁻¹ (NH₄)₂SO₄. With the increasing national emphasis on environmental protection and recycling, it is necessary to find a cost‐effective and environment‐friendly alternative to recover the (NH₄)₂SO₄. This paper reports on investigations of the electrodialysis process for (NH₄)₂SO₄ recovery from isoelectric supernatant pretreated by ceramic membrane. RESULTS: For ceramic membrane pretreatment, the optimal pore size chosen was 0.2 µm. After a 250 min run, permeate flux was still maintained at 90 L m⁻² h⁻¹ (v = 2.8 m s⁻¹, ΔTMP = 0.12 MPa, concentration factor = 7). Meanwhile, the total solids and proteins content in condensed supernatant were high, up to 78 g L⁻¹ and 24 g L⁻¹, respectively, which greatly favors future cell protein harvest. With the chosen current density of 17 mA cm⁻², the energy consumption and time for six consecutive batches for electrodialysis were 2.6–2.7 kW h kg⁻¹ sulfate and ∼100 min, based on ∼80% ammonium sulfate recovery from pretreated isoelectric supernatant. CONCLUSION: Ceramic membrane pretreatment was shown to be a promising pretreatment strategy, applicable to the electrodialysis process to recover ammonium sulfate from isoelectric supernatant produced during monosodium glutamate production. Copyright © 2008 Society of Chemical Industry     

Stainless steel membrane UF coupled with NF process for the recovery of sodium hydroxide from alkaline wastewater in chitin processing

The recovery of sodium hydroxide from alkali wastewater in chitin processing was investigated using stainless steel ultrafiltration membrane (SSM) and HDS-04 nanofiltration (NF) membranes with membrane area of 0.35 m² and 1.4 m², respectively. Flux behaviors were observed with respect to filtration time, volumetric concentration ratio (VCR), operating pressure, temperature, and cleaning. As the VCR increased, the permeate flux declined while almost the same concentration of NaOH was permeable. The SSM and NF operations end with a concentrated protein solution that needed a small amount of waste acid for neutralization and easy spray drying and the permeate of the NaOH solution can be reused. Concentrations of NaOH that govern reusability of permeate were measured to be independent on VCR. The most suitable VCRs for SSM and NF in terms of maintaining relatively good membrane productivity and high rejection of protein and chemical oxygen demand (COD) were approximately 50. At a VCR of 50, the total rejections of protein, COD and suspended solid (SS) were 82.5%, 94% and 100%, respectively, while total NaOH recovery was 96% with SSM average flux 270 LMH and NF average flux 25 LMH. SSM filtration was essential for the pretreatment of the alkali wastewater before it was fed into the NF system.     

Extraction separation of Ir(III) and Rh(III) with Cyanex 923 from chloride media: a possible recovery from spent autocatalysts

Liquid–liquid extraction of Ir(III) and Rh(III) with Cyanex 923 from aqueous hydrochloric acid media has been studied. Quantitative extraction of Ir(III) was observed in the range of 5.0–8.0 mol dm^?3 HCl with 0.1 mol dm^?3 Cyanex 923, while Rh(III) was extracted quantitatively in the range of 1.0–2.0 mol dm^?3 HCl with 0.05 mol dm^?3 Cyanex 923 in toluene along with 0.2 mol dm^?3 SnCl₂. The Ir(III) was back extracted with 4.0 mol dm^?3 HNO₃ quantitatively from the organic phase while Rh(III) was stripped with 3.0 mol dm^?3 HNO₃. The extraction of Rh(III) with Cyanex 923 was not quantitative without use of SnCl₂. However in the extraction of Ir(III) a negative trend was observed in the presence of SnCl₂. Varying the temperature of extraction showed that the extraction reactions of both the metal ions are exothermic in nature, and the stoichiometric ratio of Ir(III)/Rh(III) to Cyanex 923 in organic phase was found to be 1:3. The methods developed were applied to the recovery of these metal ions from a synthetic solution of similar composition to that from leaching of spent autocatalysts in 6.0 mol dm^?3 HCl. © 2002 Society of Chemical Industry