Pervaporation performance and characterization of hydrophilic ZSM-5 zeolite membranes for high inorganic acid and inorganic salts

The hydrophilic ZSM-5 zeolite membranes are applied to separate the inorganic acid solutions and inorganic acid/inorganic salt mixtures by pervaporation,and the membrane presents good stability,dehydration,and desalination performance.Influences of inorganic acid type(H_(2)SO_(4),H_(3)PO_(4),HNO_(3),and HCl),H_(2)SO_(4)concentration(1-6 mol·L^(-1)),test temperature(60-90℃)and inorganic acid/inorganic salt type(2 mol·L^(-1)H_(2)SO_(4)and sulfate,2 mol·L^(-1)H3PO4 and phosphate)on the pervaporation performance are investigated in this work.Either for concentrating 3%(mass)H_(2)SO_(4)solution or consecutive dehydrating 20%(mass)H_(2)SO_(4)solution,the hydrophilic ZSM-5 zeolite membrane has a good dehydration performance and stability.Even though the H_(2)SO_(4)concentration and test temperature are increased to 6 M and 90℃,only H_(2)O molecules could pass through the membrane and pH value of the permeation is kept neutral.Besides,the membrane has good dehydration and desalination performance for H_(2)SO_(4)/sulfates and H_(3)PO_(4)/phosphate mixtures,and the rejection of natrium salt,molysite,and magnesium is almost 100%.

Preparation and Conducting Behavior of Amphibious Organic/Inorganic Hybrid Proton Exchange Membranes Based on Benzyltetrazole

A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.

Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor

Removal of inorganic nitrogen （inorganic-N） from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor （AEC-MBR） was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/（m^3·d） helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen （DO） on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BODs/ammonia nitrogen （NH4＋-N） at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4^＋-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m^3, and the energy consumption was approximately 0.72 kWh/m^3 at the flux of 8 L/（m^2-h）.

PVDF-Based Micro Inorganic Fillers-Containing Polymer Electrolyte Membranes

Polymer electrolyte membranes based on poly （vinylidene fluoride-co-hexafluoropropylene） （PVDFHFP） with and without different types of micro inorganic fillers were prepared by phase-inversion process. Morphologies, porosities and electrochemical properties ＇of the as-prepared membranes were investigated by means of scanning electronic microscopy （SEM）, PC （propylene carbonate） uptake and alternating current （AC） impedance technique. Compared with other membranes, the membrane with micro SiO2 filler shows a dense morphology so that its PC uptake is the highest, namely, 339 %. The membrane filled with micro TiO2 exhibits good electrochemical performances： the ion conductivity is as high as 1.1 × 10^-3 S/cm at 18 ℃, which can meet the demand of lithium ion batteries. Moreover, its initial charge-discharge efficiency exceeds 89 %. The composite membranes with micro SiO2, TiO2 and Al2O3 are more suitable for the utilization in lithium ion batteries due to better cycle.ability, whereas the battery assembled with the blank membrane containing no inorganic fillers encounters a short circuit after the 5th cycle.

Progress in Inorganic Nanofiltration Membranes

Inorganic nanofiltration(NF)membranes as a new kind of membranes appeared a few years ago.Thisreview presents the progress in inorganic NF membranes during recent years.Synthesis,characterization,performance,and application of inorganic NF membranes are emphatically introduced,and the trends of devel-opment are also discussed.

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

CFD-based optimization and design of multi-channel inorganic membrane tubes

As a major configuration of membrane elements,multi-channel porous inorganic membrane tubes were studied by means of theoretical analysis and simulation.Configuration optimization of a cylindrical 37-channel porous inorganic membrane tube was studied by increasing membrane filtration area and increasing permeation efficiency of inner channels.An optimal ratio of the channel diameter to the inter-channel distance was proposed so as to increase the total membrane filtration area of the membrane tube.The three-dimensional computational fluid dynamics(CFD) simulation was conducted to study the cross-flow permeation flow of pure water in the 37-channel ceramic membrane tube.A model combining Navier–Stokes equation with Darcy's law and the porous jump boundary conditions was applied.The relationship between permeation efficiency and channel locations,and the method for increasing the permeation efficiency of inner channels were proposed.Some novel multichannel membrane configurations with more permeate side channels were put forward and evaluated.

A Diffusion Equation for Gas Permeation though an Inorganic Porous Membrane in the Knudsen Regime

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Conventional processes and membrane technology for carbon dioxide removal from natural gas:A review

Membrane technology is becoming more important for CO,_ separation from natural gas in the new era due to its process simplicity, relative ease of operation and control, compact, and easy to scale up as compared with conventional processes. Conventional processes such as absorption and adsorption for CO2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance. Polymeric membranes are the current commercial membranes used for CO2 separation from natural gas. However, polymeric membranes possess drawbacks such as low permeability and selectivity, plasticization at high temperatures, as well as insufficient thermal and chemical stability. The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives, especially inorganic membranes due to their higher thermal stability, good chemical resistance to solvents, high mechanical strength and long lifetime. Surface modifications can be utilized in inorganic membranes to further enhance the selectivity, permeability or catalytic activities of the membrane. This paper is to provide a comprehensive review on gas separation, comparing membrane technology with other conventional methods of recovering CO2 from natural gas, challenges of current commercial polymeric membranes and inorganic membranes for CO2 removal and membrane surface modification for improved selectivity.

PREPARATION OF SILICA MOLECULAR SIEVE MEMBRANE FOR HYDROGEN SEPARATION

A ceramic tube supported γ alumina silica inorganic composite membrane was made by modifying a ceramic tube supported γ alumina film with a silica sol using sol gel method. The thickness of the silica thin film was 750? and the pore diameter was less than 5?.The prepared silica molecular sieve membrane displayed a high hydrogen permeability and high selectivities of H 2/N 2 and H 2/CO 2 gas mixtures. This composite membrane can be used to separate high purity hydrogen of more than 99 5% from various kinds of industrial waste gas mixtures containing hydrogen.

Recent developments in high-performance Nafion membranes for hydrogen fuel cells applications

As a promising alternative to petroleum fossil energy,polymer electrolyte membrane fuel cell has drawn considerable attention due to its low pollution emission,high energy density,portability,and long operation times.Proton exchange membrane(PEM)like Nafion plays an essential role as the core of fuel cell.A good PEM must have satisfactory performance such as high proton conductivity,excellent mechanical strength,electrochemical stability,and suitable for making membrane electrode assemblies(MEA).However,performance degradation and high permeability remain the main shortcomings of Nafion.Therefore,the development of a new PEM with better performance in some special conditions is greatly desired.In this review,we aim to summarize the latest achievements in improving the Nafion performance that works well under elevated temperature or methanol-fueled systems.The methods described in this article can be divided into some categories,utilizing hydrophilic inorganic material,metal-organic frameworks,nanocomposites,and ionic liquids.In addition,the mechanism of proton conduction in Nafion membranes is discussed.These composite membranes exhibit some desirable characteristics,but the development is still at an early stage.In the future,revolutionary approaches are needed to accelerate the application of fuel cells and promote the renewal of energy structure.

Preparation of Palladium-Silica Conjugated Membrane for Selective Hydrogen Permeation

Palladium membranes were prepared on an α-alumina support bymetal-organic compound chemical vapor deposition (MOCVD) method frompalladium (II) acetate precursor. Permeation properties of hydrogenand helium gas were studied as a function of the number of times ofdeposition of palladium on the peeling off phenomenon of palladium,which is common in electroless plated membrane, was observed. Silicawas introduced into the pores to prevent the palladium grain frompeeling off. The palladium-silica conjugated membrane does not showthe peeling off phenomenon and can withstand the high temperature upto 800 deg. C which is the upper limit of our apparatus.

Advanced Catalytic Membrane Characterisation and Gas Permeation Properties for Enhanced Ethyl Lactate Conversion

In this work, membrane evaluation, gas permeation properties and characterisation have been presented. A silica composite membrane was prepared, characterized and used for the permeation tests with four carrier gases to determine the most suitable carrier gas for enhancing the analysis of esterification product with gas chromatograph. The carrier gases used for the permeation tests were carbon dioxide (CO2), argon (Ar), helium (He) and nitrogen (N2). The permeation analysis was carried out between the gauge pressure range of 0.10 - 1.00 bar and temperature of 60℃. The gas flow rate was found to increase with respect to gauge pressure. The order of the gas flow rate with respect to the gauge pressure was Ar > CO2 > He > N2. The surface morphology and elemental composition of the membrane were analysed using scanning electron microscopy coupled with energy dispersive analysis of x-ray (the Zeiss EVO LS10). The SEM results exhibited a defect-free surface while the EDAX results identified different elements on the spectra including titanium (Ti), silicon (Si) and oxygen (O). Liquid nitrogen adsorption method (Quantachrome 2013 model) was used for the surface area and pore size distribution analysis. The Brunauer-Emmette-Teller (BET) surface area results of the 5th and 6th dip-coated membranes were 1.497 and 0.253 m2/g respectively, while the Barrette-Joyner-Halender (BJH) curves gave a pore size of 4.184 and 4.180 nm respectively for the 5th and 6th dip-coated membranes indicating a mesoporous structure. The BET curve exhibited a type IV isotherm. The BJH curve of the 6th dip-coated membrane showed a significant reduction in flow rate after the modification process. The membrane recorded a permeance in the range of to . The permeance relationship with the inverse square root of the gas molecular weight showed a linear proportionality with the flow of carrier gases confirming Knudsen flow mechanism of gas transport.

Synthesis of Gas Transport through Nano Composite Ceramic Membrane for Esterification and Volatile Organic Compound Separations

The transport behaviour of carrier gases with inorganic catalytic ceramic membrane used for ethyl lactate production and VOC （volatile organic compound） recovery in the gauge pressure range of 0.10-1.00 bar and temperature range of 333 K was investigated. The gases include Ar （argon）, N2 （nitrogen） and CO2 （carbon dioxide）. The gas kinetic diameter with respect to permenace was found to occur in the order of At 〉 CO2 〉 N2, which was not in agreement with molecular sieving mechanism of transport after the first dip-coating of the support. However, gas flow rate was found to increase with gauge pressure in the order of Ar 〉 CO2 〉 N2, indicating Knudsen mechanism of transport. The porous ceramic support showed a higher flux indicating Knudsen transport. The surface image of the dip-coated porous ceramic membrane was characterised using SEM （scanning electron microscopy） to determine the surface morphology of the porous support at 333 K.

二氧化碳膜分离材料及其性能研究进展

碳捕集、利用与封存技术是能源行业绿色发展的重要途径。与化学吸收法、变压吸附法和低温蒸馏法等传统工艺相比,膜分离法具有低能耗、高效率、小型化、环境友好、易与其他技术集成等优势。目前,膜材料的选择、改性以及对膜结构的重构是提高膜材料分离性能的关键。该文总结对比了有机聚合物膜、无机膜及混合基质膜的研究进展,并对其分离机理、材料及性能进行了介绍,重点综述了材料的改性研究及用于制备混合基质膜的填充材料,展望了CO_(2)分离膜材料性能改进的研究方向及膜分离技术所面临的挑战。

膜蒸馏处理脱硫废水过程中污染物组成、分布及形成机理

研究了聚偏氟乙烯(PVDF)膜膜蒸馏处理脱硫废水过程中污染物对膜通量的影响,并确定处理过程中不同时期造成通量变化的先驱污染物和主导污染物。流速对污染物的分布起主导作用。采用三维单相计算流体力学(CFD)方法来评估膜模块系统中的流动状态,并通过SEM、X射线能谱仪(SEM-EDS)、FTIR分析不同污染时期污染物在膜表面水平方向和垂直方向上的分布、组成和结构。研究发现,膜通量的变化主要分为2个阶段:缓慢下降阶段和快速下降阶段,两阶段截然不同的通量变化归因于主导污染物的差异。有机污染物是前期导致通量缓慢下降时的先驱性污染物,矿物结垢是后期通量急速下降的主导因素。有机污染物主要包括腐殖酸和富里酸,在膜蒸馏过程中通过与膜表面的疏水-疏水相互作用首先沉积在膜表面造成通量的缓慢下降;矿物污染物主要是硫酸钙,随着进料液的浓缩,在液体中成核结晶,在膜表面快速生长导致通量的快速降低。

烧结制度对煤矸石基支撑体的性能影响

为了实现固体废弃物高值化利用和解决陶瓷膜成本过高等问题,以固体废弃物煤矸石为骨料,Na_(2) CO_(3)为烧结助剂,羟丙基甲基纤维素(HPMC)为粘结剂以及碳粉为造孔剂,利用挤压成型法和固态粒子烧结法制备低成本管式煤矸石基陶瓷膜支撑体,研究了烧结温度和保温时间对支撑体物化性能的影响。利用扫描电镜(SEM)、X射线衍射(XRD)、压汞法等方法对煤矸石基支撑体的表面微观形貌、晶相组成、理化性能等进行系统表征。结果表明:支撑体的晶相组成主要为石英、钠长石、白云母;在Na_(2) CO_(3)、HPMC以及碳粉的添加量(质量分数)分别为4%、3%、15%的基础上,以及烧结温度900℃、保温2 h的条件下,制备出的支撑体综合性能最佳,此时支撑体的纯水通量为2468 L/(m^(2)·h·MPa),抗折强度为24.96 MPa,孔隙率为43.38%,耐酸碱腐蚀率分别为4.45%、0.62%。本文的研究结果表明煤矸石基支撑体可实现固体废弃物高值化利用并获取经济效益的目的。

饮用水处理过程中天然有机物引起的超滤膜污染机制研究进展

天然有机物(NOM)存在于地表水、地下水和土壤水中。超滤(UF)膜技术具有运行压力小、设备集成化程度高和占地面积小等优势,但NOM造成的复合污染使超滤膜在水处理的应用管理变得复杂。本文在概述NOM的来源、组成和化学性质的基础上,通过分析不同结构特征的NOM间的相互作用机制,阐述了不同结构特征的NOM的复合膜污染。从离子与NOM络合的影响因素、络合对NOM理化性质的影响等,分析了离子与NOM的复合膜污染。最后,分析了目前研究面临的挑战,并对未来的发展方向进行了展望。

纳滤膜对不同水源中无机物处理效果及膜污染特性分析

针对不同水源地(引黄水库、微污染湖泊、河流)水质差异问题,分别选取了不同典型水体(鹊山水库、南阳湖和沂河)开展纳滤实验,探究了NF1、NF2两种纳滤膜对不同水源中无机污染物的去除效能与膜污染情况。结果表明,3种原水经过预处理和纳滤处理后pH值略有下降,浊度均在0.186 NTU之下,总硬度、溶解性总固体(TDS)的含量均较低。NF1和NF2对一价离子平均去除率分别达到92.35%,42.35%以上,对二价离子的平均去除率分别可达97.87%,85.67%以上;NF2在处理南阳湖原水后,无机污染情况较为严重;酸碱联合冲洗对污染膜的修复效果更好。