二硫化钼纳米片基水处理纳滤/反渗透膜研究进展

二硫化钼（MoS₂）纳米片的层内固有缺陷以及层间纳米限域通道的存在,有利于提高水处理纳滤/反渗透（NF/RO）膜的渗透选择性。本文首先介绍了MoS₂纳米片的“三明治”结构,其具有易功能化、高吸附容量和氧化还原去除能力、层间纳米限域通道的光滑性和稳定性及抗污染等特性;然后重点综述了MoS₂基纳米孔膜、层叠膜和混合基质膜的制备方法及膜性能的影响因素;最后总结了MoS₂纳米片基水处理NF/RO膜未来发展亟待解决的关键问题,主要包括研究大尺寸纳米片和均匀亚纳米孔的可控制备方法,开发超薄、高度有序的MoS₂分离层构建方法,探索层间纳米限域通道内分子和离子的传输行为和潜在的分离机理,开发增强与聚合物基质界面相容性的改性策略,对下一代高性能水处理NF/RO膜的研发具有启发意义。     

Surface modification of polyamide and poly(vinylidene fluoride) membranes

Experimental results from the gas‐plasma treatment and electron‐beam irradiation of polyamide (PA) and poly(vinylidene fluoride) (PVDF) membranes to improve their wettability and to evaluate protein adsorption at their surface are presented. The wettability of the membrane surface was determined by contact angle measurements; the analysis of the surface composition was performed by X‐ray photoelectron spectroscopy (XPS). We observed that a reduction in the water contact angle was not always indicative of a reduction in the protein adsorption and, furthermore, that a charge at the surface of the modified membrane seemed to be a major factor in the protein adsorption process. Furthermore, the XPS results shed some light on the modification mechanism of PVDF and PA by electron‐beam irradiation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Formation of pervaporation membranes from polyphosphazenes having hydrophilic and hydrophobic pendant groups: Synthesis and characterization

A series of new polyphosphazene polymers were synthesized using three different pendant groups with the goal of probing structure–function relationships between pendant group substitution and polymer swelling/water flux through thin dense films. Formation of polymers with relative degrees of hydrophilicity was probed by varying the stoichiometry of the pendant groups attached to the phosphazene backbone: p‐methoxyphenol, 2‐(2‐methoxyethoxy)ethanol, and o‐allylphenol. The polymers in this study were characterized using NMR, thermal methods, and dilute solution light‐scattering techniques. These techniques revealed that the polymers were amorphous high polymers (M_w = 10⁵–10⁷) with varying ratios of pendant groups as determined by integration of the ¹H‐ and ³¹P‐NMR spectra. Thin dense film membranes were solution‐cast with azo‐bis(cyclohexane)carbonitrile included in the matrix and crosslinked using thermal initiation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 422–431, 2001     

Formation of bicontinuous,hydrophobic nylon 12 membranes via cold-solvent-induced phase separation for membrane distillation application

Skinless nylon 12 microporous membranes were prepared via a cold-solvent-induced phase-separation process from a binary nylon 12–formic acid system. Through the incorporation of an aging step, polymer nucleation in the dope was enhanced, and the formed membranes exhibited a special particulate structure composed of interlocked sticklike or sheaflike crystallites, which coexisted with continuous microporosity. The crystallite size was affected by the polymer concentration in the dope and the aging time; for example, aging alone allowed for the reduction of the particle diameter from about 20 μm to about 1 μm. Because the membranes were skinless and hydrophobic (contact angles ≈ 105°), they were potentially appropriate for desalination via membrane distillation (MDi). For the case of desalting 3.5% NaCl_(aq) by means of direct-contact MDi, very high rejection ratios (∼99.6%) were achieved for all membranes under the operation conditions (temperature of the hot stream = 50°C, temperature of the cold stream = 20°C, and circulation rate = 0.7 L/min), whereas the highest permeation flux obtainable was 5.15 L/m² h. The membranes were strong, with tensile strengths ranging from 4.7 to 6.3 N/mm². Finally, we discovered a shift from α to γ structure as the dope polymer increased, whereas the crystallinity was about 27% in all cases. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47036.     

亲水/疏水复合膜强化膜蒸馏深度处理工业废水的研究进展

工业废水中通常含有多种疏水性有机污染物及表面活性剂,传统疏水微孔膜用于膜蒸馏处理工业废水的过程中,这些污染物容易沉积在膜表面引发膜污染和膜润湿,导致膜蒸馏过程的低效甚至失败。亲水/疏水复合膜是一种表层亲水而底层疏水的非对称膜材料,可通过在膜表面形成水合层减缓污染物的吸附累积,同时保留疏水基底膜对污染物的高截留率,用于膜蒸馏过程可有效强化其处理复杂工业废水的效果。本文概述了构筑亲水/疏水复合膜的仿生学原理与表面润湿理论,介绍了复合膜常用的制备方法,重点分析了多种亲水材料改性制备的复合膜用于膜蒸馏深度处理工业废水的强化效果及强化机制,认为复合膜表面形成的亲水层可有效抑制工业废水中疏水性污染物与膜表面的疏水-疏水相互作用,减轻膜污染及膜润湿倾向,提高污染物截留效率,而氧化石墨烯等亲水物质可加速水分子通过,提升膜蒸馏产水通量。最后指出未来亲水/疏水复合膜的发展可以通过建立污染物在复合膜中的传递模型,进一步探究复合膜对工业废水处理过程的强化机制,通过优化调控复合膜结构,提升复合膜对工业废水中多种污染物的截留率和抗污染性能,实现膜蒸馏抗污染性、截留率和产水通量的同步提升,并通过开展中试研究验证复合膜用于工业废水深度处理的经济性和长期稳定性。     

Adsorption of copper on specifically modified polyamide sorbent

A novel, specific sorbent based on polyamide covalently immobilized with dead yeast cells by glutaraldehyde was prepared and characterized. This sorbent exhibits a high capacity for metal complexation based on multifunctional groups of dead cells, as well as a good stability for reuse based on the crosslinking agent, glutaraldehyde. The Cu²⁺ sorption characteristics of the polyamide modified with immobilized dead cells were studied and compared to those of the polyamide chemically modified without cells. The adsorption capacity of specifically modified polyamide was about 19‐fold higher than the chemically modified polymer. The adsorption isotherms of Langmuir and Freundlich for the new specific sorbent were determined. The effect of pH, temperature and co‐ions (Zn²⁺, Pb²⁺, Co²⁺, Ca²⁺ and Mg²⁺) on the Cu²⁺ sorption capacity were studied. The effectiveness of heavy metal desorption and the coefficient of recovery of sorption ability were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 80–85, 2003     

A systematic study on the effects of synthesis conditions of polyamide selective layer on the CO2/N2 separation of thin film composite polyamide membranes

Different top layer fabrication methods (amine-first, acid-first, spin coating), organic phase solvents (hexane, heptane, mixed hexane/heptane), acid acceptors (triethylamine, sodium carbonate, sodium hydroxide), and surfactant sodium dodecyl sulfate concentrations (0, 0.05, and 0.1 wt%) were utilized to fabricate thin film composite polyamide membranes for CO₂/N₂ separation. The results, according to an L9 orthogonal array of Taguchi approach, showed that employing acid-first method increases both CO₂ permeance and CO₂/N₂ selectivity of the membranes at a feed gas pressure of 3 bars. On the other hand, sodium hydroxide, and triethylamine should be used, as acid acceptors, to maximize CO₂ permeance and CO₂/N₂ selectivity, respectively. Moreover, the use of hexane solvent and 0 wt% surfactant led to maximum permeance, while, hexane solvent and 0.1 wt% surfactant were needed to reach the highest selectivity. The above level setting of synthesis parameters also resulted in the minimum sensitivity of the fabrication process to the noise factors effects. As shown by the analysis of variance, acid acceptor, and organic solvent types were the most influential parameters on CO₂ permeance and CO₂/N₂ selectivity, respectively. The effects of fabrication method and surfactant concentration, as single factors, on permeation/selectivity responses were also investigated.     

Oxidative degradation of polyamide reverse osmosis membranes: Studies of molecular model compounds and selected membranes

Selected aromatic amides were used to model the chemical reactivity of aromatic polyamides found in thin‐film composite reverse osmosis (RO) membranes. Chlorination and possible amide bond cleavage of aromatic amides upon exposure to aqueous chlorine, which can lead to membrane failure, were investigated. Correlations are made of the available chlorine concentration, pH, and exposure time with chemical changes in the model compounds. From the observed reactivity trends, insights are obtained into the mechanism of RO membrane performance loss upon chlorine exposure. Two chemical pathways for degradation are shown, one at constant pH and another that is pH‐history dependent. An alternative strategy is presented for the design of chlorine‐resistant RO membranes, and an initial performance study of RO membranes incorporating this strategy is reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1173–1184, 2003     

Preparation of highly selective nanofiltration composite membranes based on a novel soluble rigidly contorted monomer

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.     

Pervaporation separation of ethanol/water mixture using modified zeolite filled PDMS membranes

In this article, the composite polydimethylsiloxane (PDMS) membranes supported by cellulose acetate (CA) microfiltration membrane were successfully prepared by adding modified zeolite particles with a silane coupling agent, NH₃–C₃H₆–Si(OC₂H₅)₃. The sorption and diffusion behaviors of ethanol and water in the films were studied. The results showed that with the increase in the modified zeolite content, the solubility selectivity increased, but the diffusion selectivity first increased, then decreased. The effects of modified zeolite content and feed temperature on the pervaporation performance of the composite membranes in 10 wt % ethanol/water mixture were also investigated. When modified zeolite loading was 20 wt %, for 10 wt % ethanol/water mixture at 40°C, the permeate flux was 348.7 g·m^?2·h^?1, the separation factor was 14.1, and the permeate separate index was 4568, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41897.     

Effect of surface modifying macromolecules stoichiometric ratio on composite hydrophobic/hydrophilic membranes characteristics and performance in direct contact membrane distillation

The stoichiometric ratio for the synthesis components of hydrophobic new surface modifying macromolecules (nSMM) was altered systematically to produce three different types of nSMMs, which are called hereafter nSMM1, nSMM2, and nSMM3. The newly synthesized SMMs were characterized for fluorine content, average molecular weight, and glass transition temperature. The results showed that fluorine content decreased with increasing the ratio of α,ω‐aminopropyl poly(dimethyl siloxane) to 4,4′‐methylene bis(phenyl isocyanate). The synthesized nSMMs were blended into hydrophilic polyetherimide (PEI) host polymer to form porous hydrophobic/hydrophilic composite membranes by the phase inversion method. The prepared membranes were characterized by the contact angle measurement, X‐ray photoelectron spectroscopy, gas permeation test, measurement of liquid entry pressure of water, and scanning electron microscopy. Finally, these membranes were tested for desalination by direct contact membrane distillation and the results were compared with those of commercial polytetraflouroethylene membrane. The effects of the nSMM type on the membrane morphology were identified, which enabled us to link the membrane morphology to the membrane performance. It was found that the nSMM2/PEI membrane yielded the best performance among the tested membranes. In particular, it should be emphasized that the above membrane was superior to the commercial one. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Electrospun polymeric membranes: Potential removal of endocrine disrupting compounds using solid membrane extraction and filtration processes

The present study aims to prepare polymeric membranes by electrospinning to apply in the removal of estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) in aqueous samples. Polymeric membranes of polyamide-6 (PA6), polycaprolactone (PCL), polylactic acid (PLA), and poly (butylene adipate-co-terephthalate) (PBAT) were obtained, characterized, and tested as sorbent material in processes of solid membrane extraction (SME) and membrane filtration. The efficiencies of the membranes after washing and/or conditioning processes were compared. The characterizations showed membranes with nanometer-diameter threads (between 250 and 1200 nm, on average). The four membranes' morphology, chemical composition, and thermal stability were like previous works. PBAT membranes were considered the most effective SME technique as a differential, with 44%–71% removal. For the membrane filtration process, the highest removal values were obtained for the PBAT membrane (82%–91%), which was also efficient in filtering a surface water sample from River Guaíba. PBAT polymeric membrane effectively removes and recovers the studied hormones, lowering production costs and allowing internal and external modifications. These aspects demonstrate that the obtained membranes offer an efficient material in extracting E1, E2, and EE2, of high simplicity, low cost, and green chemistry.     

Processing of black liquors by UF/NF ceramic membranes

This study deals with the treatment of black liquor from wood pulping by means of membranes. UF/NFmembranes with a skin layer of TiO₂ and ZrO₂ have been applied to recover water and to concentrate the residual effluent. Three different membranes with molecular weight cut-off of 1, 5 and 15 kDa have been checked. The membranes have been tested either in single stage operation or in cascade. Total dissolved solids, organic matter, organic to mineral matter ratio and ash have been determined. In addition, chemical oxygen demand (COD) retention was calculated by measuring in the feed solution as well as in the permeate and in the concentrated solution. During the concentration step the steady state was reached after a few minutes running. There was not significant change in the permeate flow until the volume was reduced at half. Only the 15,000 Da membrane showed continuous permeate flow declining. Regardless the membrane used, dry matter, organic matter and COD analyses showed that the retention of organic substances fell in the range of 60-70%, depending on the conditions selected.     

Effects of hydrophilic/hydrophobic surfaces on polymer‐complexation kinetics

To establish hydrophilic/hydrophobic effects on polymer‐complexation kinetics, chitosan resins were prepared by radical copolymerization of methacryloyl‐modified chitosans with 2‐hydroxyethyl methacrylate and/or styrene monomers. The primary particles of the gelled copolymers in the suspensions were nicely solidified by basic coagulation bath to form globular beads. Degree of the hydrophilic/hydrophobic properties was controlled by the copolymerization ratio, and each ion‐adsorption kinetics was evaluated by batch method. The initial rate of adsorption in hydrophilic chitosans was higher than that in hydrophobic chitosans, which was attributed to less thickness of the boundary film. We quantitatively evaluated the rate‐determining steps by the initial‐rate analysis, in which the viscosity of the suspension contributes to the film‐diffusion kinetic resistance. The role of hydrophilic/hydrophobic properties of the resins is reasonably rationalized to the length of the boundary films by considering long‐range interactions between the ion and surface. Our results are robust evidence for the ion‐surface interactions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46493.     

Preparation of antibacterial and antifungal breathable polyether block amide/chloropropane diol membranes via solution casting

A highly hydrophilic block copolymer polyether block amide (PEBA) is modified with chloropropane diol (CPD) to impart antibacterial and antifungal properties to it without compromising with its breathability. The antibacterial properties of modified membranes are evaluated against Staphylococcus aureus (S. aureus, Gram positive) and Escherichia coli (E. coli, Gram negative) bacteria by membrane culture method. CPD plays an important role in the antibacterial property with the inhibition rate reaching 99.99% for CPD modified membranes which was 27.55% and 16.82% for pristine membrane (against S. aureus and E. coli respectively). The antifungal properties studied against Aspergllus niger, Penicillium pinophilum, Aureobasidium pullulans, Chaetomium globosum, and Trichoderma virens show heavy‐growth of fungi for pristine PEBA membrane while no growth was observed in case of CPD modified membranes. Breathability of membrane is determined in terms of water vapor transmission rate (WVTR) and it increase from 1496 g/m²/day to 2354 g/m²/day after modification. The membranes are characterized by FTIR‐ATR, SEM‐EDX, DSC, and TGA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46097.     

Dual drug release from CO2‐infused nanofibers via hydrophobic and hydrophilic interactions

This study investigated the effects of hydrophobic–hydrophilic interactions on dual drug release from CO₂‐infused nanofibers scaffolds (PCL, PCL–gelatin, and PCL “core” PCL–gelatin “shell”) using BODIPY 493/503 and Rhodamine B fluorescent dyes as drug models. Favorable dye–scaffold interactions increased total dye loading and promoted steady, more linear release. Unfavorable dye–scaffold interactions reduced overall loading and led to a greater burst release of dye. However, when CO₂ was used to infuse dye into an unfavorable scaffold, the changes in loading and release were less pronounced. When two dyes were infused, these behaviors were accentuated due to interactions between the dissolved forms of the dyes. Core–shell composite nanofibers displayed radically different release properties versus pure PCL–gelatin fibers when treated with dyes via CO₂ infusion. Dye release from core–shell scaffolds was highly sensitive to both interactions with scaffolds and the phase of CO₂ used to infuse the compounds of interest. By using different phases of CO₂ to partition dyes into hydrophobic and hydrophilic sections of core–shell nanofibers, such interactions can be manipulated to develop a bimodal drug release system with potential application in drug delivery or tissue engineering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42571.     

Morphology of membranes formed by the isothermal precipitation of polyamide solutions from water/formic acid systems

Membranes were prepared by the direct and isothermal immersion of polyamide solutions in a formic acid/water bath. A crystalline polycaprolactam homopolymer, nylon 6, and a largely amorphous terpolymer of nylon 6, nylon 66, and nylon 610 were precipitated from solutions to form complex morphologies on the top and bottom surfaces and cross sections of the membranes. Terpolymer membranes exhibited the characteristics of a liquid–liquid phase‐separation process. According to the conditions of the solution and bath, nylon 6 precipitated to form membranes that showed dominance of crystallization or liquid–liquid phase separation. By precipitation from a solution containing a high concentration of a nonsolvent into a bath containing a high concentration of formic acid, skinless nylon 6 microporous membranes were formed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 944–960, 2005     

Organic fouling of RO membranes: Investigating the correlation of RO and UF fouling resistances for predictive purposes

This study examines the characteristics of deposits from dead-end UF and cross-flow RO filtration of dilute mixtures of sodium alginate (SA) and humic acids (HA), which are representative of common foulants in RO and NF feed waters. The data are interpreted in terms of specific cake resistance, α. The presence of alginates in the mixed fouling layers, even in relatively small percentage, imparts characteristic properties to these deposits; i.e. a gel-like structure which is associated with reduced compressibility and permeability. With SA/HA mixtures, high rejection of organic species and high deposition factors are obtained in UF and RO tests, respectively. The specific resistance of mixed SA and HA deposits tends to increase with increasing SA concentration in solution. The resistances α exhibit fairly strong (power law) dependence on the pressure difference across the cake, ΔΡ_c, for both RO and UF tests. The fairly satisfactory correlation of resistance α versus ΔΡ_c data, obtained from both types of tests (for the mixtures of organic species tested at small salinity) is a significant result of this work. Based on this correlation, an approach is suggested for estimating fouling index I and initial membrane fouling rate of a specific RO process, relying on limited UF tests.     

A thin film composite membrane supported by a hydrophilic poly(vinyl alcohol‐co‐ethylene) nanofiber membrane: Preparation,characterization, and application in nanofiltration

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.