Impact of Organic Solvents on Physicochemical Properties of Nanofiltration and Reverse‐Osmosis Membranes

Polymeric membranes subjected to the permeation of n‐hexane were characterized and the influence of pretreatment with ethanol on the properties of the membranes was studied to assess membrane performance and stability. The results suggest that the selectivity of the membrane depends not only on the pore size, but also to a great extent on the interaction between solvent and polymer. An increase in membrane roughness and contact angle was observed for all membranes after pretreatment with ethanol and n‐hexane permeation. Moreover, the surface free energy decreased after solvents exposure, indicating an increase in membrane surface hydrophobicity and polymer swelling. The studied membranes show feasibility of use for the recovery of solvents, if suitable process parameters are selected.     

有机蒸汽分离膜在乙烯回收中的应用

介绍了有机蒸汽分离膜的分离原理,并介绍了利用膜法乙烯回收技术应用于环氧乙烷/乙二醇装置循环排放气中回收乙烯的效果。使用该技术后,降低了乙烯及甲烷的消耗,乙烯回收率达90%以上。     

膜分离技术在镀镍漂洗水回收中的应用 Ⅰ漂洗水的预浓缩

简述了采用膜分离技术浓缩镀镍漂洗水的可行性 ,以及回收利用漂洗水中的镍和水资源。实验的结果为实际系统的设计和运行提供依据和借鉴。膜分离技术应用于电镀废水处理将带来显著的社会效益。     

膜在生物技术中的应用

综述了膜在生物技术方面的应用。概述了纳滤膜的基本原理。着重介绍了纳滤膜在食品工业，生物化工与制药工业，染料工业等方面的一些应用。     

Recent advances in nanofiltration,reverse osmosis membranes and their applications in biomedical separation field

In the face of human society’s great requirements for health industry, and the much stricter safety and quality standards in the biomedical industry, the demand for advanced membrane separation technologies continues to rapidly grow in the world. Nanofiltration(NF) and reverse osmosis(RO) as the highefficient, low energy consumption, and environmental friendly membrane separation techniques, show great promise in the application of biomedical separation field. The chemical compositions, microstr...     

Removal of organics from aqueous solutions by commercial RO and NF membranes of characterized porosities

Removal of organic pollutants of petrochemical and agrochemical origin by some commercial reverse osmosis (RO) and nanofiltration (NF) membranes of characterized porosity was investigated. The rejection of organics was shown to depend on both the membrane properties like pore size, membrane material, membrane charge and solute characteristics such as molecule size, charge and polarity. The rejection of the small nonionized organic molecules by the tight pore membranes is influenced by both the sieving parameters (solute and pore size) and by the physicochemical interactions. The rejection of the same pollutants by the wider pore membranes is dominantly influenced by the physicochemical interactions. The rejection of pesticides is prevalently governed by the sieving mechanism based on the size of the solute molecule and the membrane pore size. However, the physicochemical effects cannot be totally neglected, and they can contribute to the rejection of some pesticides by certain membranes.     

Separation performance of a nanofiltration membrane influenced by species and concentration of ions

Nanofiltration (NF), which has been largely developed over the past decade, is a promising technology for the treatment of organic and inorganic pollutants in surface and ground waters. The ESNA 1 membrane from the Nitto Denko Corporation of Japan is made of aromatic polyamide, which provides salt rejection from 50% to 90%. In this paper permeation experiments of aqueous solutions of five chlorides (NH₄Cl, NaCl, KCl, MgCl₂ and CaCl₂), three nitrates (NaNO₃, Mg(NO₃)₂ and Ca(NO₃)₂), and three sulfates (NH₄)₂SO₄, Na₂SO₄ and MgSO₄) were carried out. The effects of species and concentration of salts on the separation performance of the ESNA 1 membrane were investigated. The experimental results showed that the rejection to most salts by the ESNA 1 membrane decreased with the growth of the concentration. Then, the reflection coefficient and solute permeability of ESNA 1 membrane were calculated by the Spiegler-Kedem equation from experimental data. The reflection coefficients of the ESNA 1 membrane to salts are all above 0.95. The salt permeabilities, except for magnesium and calcium salts, increased with the growth of concentration. The sequence of rejection to anions by the ESNA 1 membrane is R(SO²⁻₄) > R(Cl⁻) > R(NO⁻₃) at the same concentration which ranges from 10 mol/m³ to 100 mol/m³. The sequence of rejection to anions by the ESNA 1 membrane can be written as follows: R(Na⁺) > R(K⁺) > R(Mg²⁺) > R(Ca²⁺) at 10 mol/m³ concentration and R(Mg²⁺) > R(Ca²⁺) > R(Na⁺) > R(K⁺) at 100 mol/m³ concentration.     

膜分离技术在酶法生产L-苯丙氨酸中的应用

酶法生产L-苯丙氨酸的工艺中，反应液中含有大量的菌体及其碎片、酶和生物大分子等杂质。要去除这些杂质，得到高质量的清液很困难，以往采用分离机来分离反应液，清液质量很不理想。改用超滤分离技术后，解决了这一难题。超滤能有效截留反应液中的杂质，清液透光率达90％以上，而且费用低、效率高，保证了后续工序的顺利进行，极大地提高了产品质量，取得了明显的经济效益。     

Phase Separation of Lactan Gum from Fermentation Broths by Addition of Water-Miscible Organic Solvents

Abstract

A microbial polysaccharide (lactan gum) produced by bacterium ATCC 55046 was precipitated from fermentation broths by the addition of ethanol, acetone, isopropanol, or tert-butanol. Compositions of the precipitate and supernatant phases were determined as a function of organic solvent concentration and used to construct binodal solubility curves. Lactan did not precipitate at bulk-mixture organic solvent concentrations below 35% (wt) ethanol, 35% acetone, 33% isopropanol, or 25% tert-butanol. At organic solvent concentrations just exceeding the solubility transition point, the precipitates were soft, moist, and sponge-like in texture, with low lactan concentrations. At higher organic solvent concentrations the precipitates were compact and dense. The maximum lactan concentration in the precipitate was 25–37%, depending on the organic solvent type and concentration. Increasing the organic solvent concentration beyond 50% for ethanol, or 70% for acetone, decreased the lactan concentration in the precipitate. No such decrease occurred for isopropanol and tert-butanol. Thus, organic solvent usage, from greatest to least, was in the order ethanol, acetone, isopropanol, and tert-butanol, but the maximum lactan concentration in the precipitate, from greatest to least, was in the order acetone, isopropanol, ethanol, and tert-butanol.     

Comparison Between Polydimethylsiloxane and Polyimide-Based Solvent-Resistant Nanofiltration Membranes

Nanofiltration using solvent-resistant membranes has become an important separation technology. Polydimethylsiloxane and polyimide are important materials for preparation of solvent-resistant nanofiltration (SRNF) membranes. In this study, the performance of commercial polydimethylsiloxane and polyimide SRNF membranes (as a trademark of MPF and STARMEM) with molecular weight cutoff values of 200–700 Da was compared in terms of organic solvent preconditioning effect, solvent compatibility, solvent flux, and solute rejection. Organic solvents employed were methanol, toluene, ethyl acetate, dichloromethane, and acetone and the organic solutes in a molecular weight range of 160–850 Da were used. Membrane preconditioning with different organic solvents did not affect membrane performance of the polydimethylsiloxane-based MPF membranes but had a significant influence on the polyimide-based STARMEM membranes. Both MPF and STARMEM membranes are not compatible in dichloromethane. MPF membranes were inert to the organic solvents and had relatively low solvent fluxes. STARMEM membranes were highly swollen in methanol and offered much higher solvent fluxes and attractive NF performance in toluene.     

超滤膜和反渗透膜联用处理苦咸水

介绍了将超滤膜和反渗透膜联用的水处理工艺,并对此种方法进行了研究。结果表明,在原水为苦咸水、含盐量在4010～4500mg／L的情况下,经预处理超滤膜和反渗透膜联用的水处理工艺对CODMn、总硬度、Cl^-的去除率分别达到了95％、98％、97％以上,脱盐率也达到97％以上,连续运行稳定,出水水质优于中华人民共和国饮用水标准。在实验基础上研究并探讨了超滤膜和反渗透膜联用的水处理工艺特性,为其在中水回用和小型饮用水装置等水处理应用提供实验依据。     

膜分离技术在生物化工领域的应用

在简要介绍膜分离技术特点及其在生物化工产品分离应用现状基础上,指出了膜分离技术在应用中仍存在的一些问题,并进一步对其解决对策进行了论述,最后对膜分离技术在生物分离方面的发展方向和应用前景进行了展望。     

Performances of RO and NF processes for wastewater reuse: Tertiary treatment after a conventional activated sludge or a membrane bioreactor

Wastewater reclamation requires processes and technologies having the ability to reduce the presence of micropollutants which are not wholly treated in conventional WWTP. Due to the complexity of membrane-solute interactions and the diversity of secondary treatment effluent (STE) matrices, deeper investigations are required to identify the major foulant species and more specifically their behaviour at high concentration in real waters. This study investigates the rejection and fouling potential of nanofiltration (NF) and low-pressure reverse osmosis (RO) membranes with two STEs sampled from i) a conventional activated sludge process coupled with ultrafiltration (CAS-UF) and from ii) a membrane bioreactor MBR (AquaRM^®, SAUR (France)). Whatever the origin of the effluent, RO seems to be the best solution to prevent pollution of tertiary effluents (expected result) but also to obtain low fouling levels. The different composition and molecular weight distribution of MBR and CAS-UF effluents can explain the different fouling behaviours that were observed.     

压力驱动膜过程在饮用水处理中的应用

膜分离过程是一种选择性高、操作简单、能耗低、无二次污染的物理分离技术 ,近三十年来发展迅速 ,已在各个领域得到了广泛应用。本文综合介绍了国外压力驱动膜过程在饮用水处理中的应用情况     

Effect of Stream Mixing on RO Energy Cost Minimization

Various mixing operations between the feed, retentate and permeate streams are studied in this work to determine their effectiveness in decreasing the specific energy consumption (SEC) of single-stage (single-pass), two-pass and two-stage reverse osmosis (RO) processes operated at the limit of the thermodynamic restriction. The results show that in a single-stage RO process, partial retentate recycling to the feed stream does not change the SEC, while partial permeate recycling to the feed stream increases the SEC if targeting the same overall water recovery. Energy optimization of two-pass membrane desalination, with second-pass retentate recycling to the first-pass feed stream and operated at the limit imposed by the thermodynamic restriction, revealed the existence of a critical water recovery. When desalting is accomplished at recoveries above the critical water recovery, two-pass desalination with recycling is always less efficient than single-pass desalination. When desalting is accomplished at recoveries below the critical water recovery, an operational sub-domain exists in which the SEC for a two-pass process with recycling can be lower than for a single-pass counterpart, when the latter is not operated at its globally optimal state. For the two-stage RO process, diverting part of the raw feed to the second stage, in order to dilute the feed to the second-stage RO, does not decrease the minimal achievable SEC of a two-stage RO process. The various mixing approaches, while may provide certain operational or system design advantages (e.g., with respect to achieving target salt rejection for certain solutes or flux balancing), do not provide an advantage from an energy usage perspective.     

膜分离技术的研究与应用

随着环境问题的日益严峻,国家对水资源更加重视,膜分离技术开始广泛应用于各个方面,作为膜分离技术的核心部件分离膜,其需求量也越来越大。文中阐述了膜分离技术的基本原理和膜技术核心部件膜的分类,介绍了膜分离技术在给水工程、工业废水、医药行业、食品行业、能源行业等方面的应用,对未来膜及其分离技术的发展进行了展望。     

苯基膦酸在有机溶剂中溶解度的测定及关联

采用本实验室自制的苯基膦酰二氯(DCPPO),在常温下缓慢水解后两次重结晶制得苯基膦酸(PPA),为白色结晶状粉末。通过酸度、质谱、核磁、熔点分析对产物进行了标定。采用滴定法测定了苯基膦酸在丙酮和苯中的溶解度,采用静态平衡法测定了在乙酸乙酯中的溶解度。并且对溶解度和温度进行了关联,回归了溶解度经验方程。     

膜分离技术在造纸工业废水回用中的应用

造纸工业是我国水资源消耗大户,造纸废水水量大、有机物含量高、造成的环境污染影响大,对造纸废水治理在全世界范围内都在关注废水回用,提高水循环利用率,减少水资源消耗和废水排放污染。膜分离技术是在一定压力下进行混合液分离的技术,近年来膜分离技术快速发展,在海水淡化、化工、食晶、医药、电子等工业废水处理中应用较多,本文对膜分离技术在国内外造纸工业废水回用中的应用研究进行了介绍,并对膜分离技术在造纸工业废水回用的研究方向进行了论述。     

海水淡化技术现状及展望

简要介绍了各种海水淡化技术,分析了传统和新型海水淡化技术的发展现状及存在的问题.指出发展具有抗污染性强、高膜通量和 NaCl 截留率高特性的膜分离海水淡化技术和集成海水淡化技术是未来海水淡化技术的发展方向.