分批操作条件下超滤过程膜面积的确定与放大

推导了在分批操作条件下确定膜面积的计算公式，利用小波实验结果，即可确定放大到中试以及生产规模所需膜面积，以红霉纱发酵滤液为例，利用外压式中空纤维膜和内压式中空纤维膜进行超滤，在１０～２０Ｌ规模取得实验数据，拟合出通量预测模型参数，然后计算出日处理８０吨发酵滤液时在不同情况下所需的膜面积，本文还讨论了影响膜面积的因素，并在１００Ｌ规模实验验证了计算是正确的。     

陶瓷膜用于硫化碱液纯化除杂研究

采用陶瓷膜对硫化碱液进行纯化除杂研究,分析了膜通量随运行时间的衰减变化趋势,确定了恢复膜通量的方法,并比较了2种陶瓷膜管的不同分离效果。结果表明,50 nm陶瓷膜能有效截留硫化碱液中的杂质,过滤硫化碱液时平均通量达到330~340 L/(m2·h),碱回收率99%以上,清液ss低于6 mg/L,满足生产需要,提高了产品品质。     

疏水性FAS-Al_2O_3复合陶瓷膜的制备与表征

选用1H,1H,2H,2H-全氟癸基三乙基氧硅烷对自制的孔梯度结构氧化铝陶瓷膜表面进行改性,制备疏水性FAS-Al_2O_3氧化铝陶瓷复合膜。通过正交实验和膜表面接触角测试确定改性液浓度、改性时间和改性次数对膜接触角的影响。通过扫描电镜分析(SEM)、孔径及其分布测试、纯水通量以及红外光谱分析测试(IR)对改性前后的氧化铝陶瓷膜理化性质进行表征。对FAS-Al_2O_3复合疏水膜进行NaCl盐溶液的气隙式膜蒸馏实验,考察疏水性FAS-Al_2O_3复合陶瓷膜对NaCl溶液的膜蒸馏通量和对NaCl的截留性能。结果表明:接触角均在130°以上,最大达到156.2°,疏水效果显著;在进料温度为80℃,冷却侧温度为15℃,进料流量为12h/L的实验条件下,对质量分数为2%的NaCl溶液的截留率为98.5%,渗透通量为12.68kg/m2·h。     

基于多孔陶瓷膜的脱硫废水负压式膜蒸馏实验

目前采用多孔陶瓷膜进行膜蒸馏的技术已有不少研究，但由于膜本身的亲水特性，需要在使用前进行疏水改性，这增加了工序和成本，且疏水性随着使用过程逐渐减弱。因此，提出一种基于多孔陶瓷膜的脱硫废水负压式膜蒸馏方法，直接采用亲水性多孔陶瓷膜，通过泵的抽吸作用使膜内溶液形成负压，以防溶液渗出膜外。为探究负压式膜蒸馏的传热传质机理，通过实验对比了亲、疏水多孔陶瓷膜在不同工况下的传递特性。实验结果表明：当膜内负压值小于膜孔内溶液毛细力时，亲、疏水多孔陶瓷膜的膜孔内分别为溶液输运和水蒸气输运；当空气流量为22L/min、废水温度和流量分别为50℃和11L/h时，亲水膜的渗透通量在1.9～3.9kg/(m²·h)之间，而疏水膜的渗透通量仅为0.13～0.25kg/(m²·h)；亲、疏水多孔陶瓷膜的热效率分别在92%和55%左右，说明亲水性多孔陶瓷膜有着更高的热效率，陶瓷膜的较高热导率有利于提升亲水膜的膜蒸馏性能；脱硫废水流量对热质传递性能影响不大，随着空气流量或者废水温度的增加，膜渗透通量随之增加。     

陶瓷膜过程强化的数学模拟

对 Altmann等人提出的数学模型进行了改进 ,提出了沉积层空隙率随操作参数变化的观点 ,较好地拟合了陶瓷膜非强化过程的实验数据。并在此基础上对湍流促进器强化过程进行了数学模拟 ,反映了操作参数对过滤通量的影响。     

陶瓷膜分离钛硅分子筛的实验与模型计算

在面向过程的陶瓷膜材料设计理论模型的基础上,以TS-1钛硅分子筛悬浮液固液分离为应用体系,计算了陶瓷膜分离过程的操作条件与渗透性能的关系,与实验结果有良好的一致性.计算表明,对于平均粒径为290 nm的钛硅分子筛体系,陶瓷膜存在最优孔径区间(200~300 nm),使膜保持高渗透通量.孔径小于200 nm时膜通量随孔径增大而增大,孔径大于300 nm时膜通量随孔径增大而减小;采用孔径为200 nm的陶瓷膜过滤钛硅分子筛,渗透通量随时间的变化关系与模型预测结果一致,稳定通量达到800 L/(m2.h).     

面向过程的陶瓷膜材料设计理论与方法(Ⅰ)膜性能与微观结构关系模型的建立

提出了面向过程的陶瓷膜设计基本研究框架,分析了膜的孔径分布与悬浮液颗粒体系粒径分布对过滤过程的影响,提出采用堵塞因子来表征膜的初始堵塞污染情况,建立了颗粒体系微滤过程中的膜微观结构与性能关系新模型,不仅可以计算膜通量随时间的变化,且能预测陶瓷膜结构参数对膜通量的影响.模拟结果与实验值有较好的一致性.     

面向过程的陶瓷膜材料设计理论与方法(Ⅰ)膜性能与微观结构关系模型的建立

提出了面向过程的陶瓷膜设计基本研究框架 ,分析了膜的孔径分布与悬浮液颗粒体系粒径分布对过滤过程的影响 ,提出采用堵塞因子来表征膜的初始堵塞污染情况 ,建立了颗粒体系微滤过程中的膜微观结构与性能关系新模型 ,不仅可以计算膜通量随时间的变化 ,且能预测陶瓷膜结构参数对膜通量的影响 .模拟结果与实验值有较好的一致性     

陶瓷膜分离净化硫氰酸钠工艺研究

采用陶瓷膜分离净化湿法腈纶溶剂硫氰酸钠物料,分析了膜通量随运行时间的衰减变化趋势及浓缩倍数与膜通量衰减的关系,确定了恢复膜通量的方法,比较了不同膜管的分离效果和分离特性。结果表明:陶瓷膜能有效截留硫氰酸钠物料中的杂质,水不溶物去除率大于75%;膜通量都随运行时间的延长而衰减,当平均膜通量低于设计膜通量时,可采用热纯水进行洗脱,使膜通量恢复;当热纯水无法使膜通量恢复,可采用化学方法或更换膜管;不同膜层厚度的膜管对膜通量影响不大,但厚层膜管的分离除杂效果好。     

关于中药水提液的粘度特征及其与膜通量的相关性初步研究

研究中药水提液的粘度对无机陶瓷膜微滤中药水提液膜通量的影响及中药水提液在微滤前后粘度变化规律。制备约200种中药（单味及复方）水提液为实验体系,在温度、压力、膜面流速恒定的条件下分别过0．2μmZrO2无机陶瓷膜,测定不同中药水提液的膜稳定通量及微滤前原液、微滤后渗透液、截留液的粘度,并用SPSS对它们的相关性进行分析。结果表明中药水提液的粘度与膜稳定通量有很大的相关性,微滤后渗透液的粘度减小且不同水提液粘度差异性变小,截留液粘度增大、且截留液粘度、粘度变化率与原液粘度呈高度显著线形相关。粘度是影响无机陶瓷膜微滤中药水提液膜通量的关键因素,在中药膜污染的防治过程中可通过提取路线的设计或对药液进行预处理降低药液的粘度从而提高膜通量,减少膜污染。     

金属膜在1，3-丙二醇发酵液预处理中的应用

考察了1,3-丙二醇发酵液金属膜过滤在不同浓缩比下的拟稳定通量、粘度及湿固含量变化,在此基础上初步探讨了膜的污染机理,提出了有效的膜清洗方法。结果表明,50nm膜适用于1,3-丙二醇发酵液的膜过滤,按料液体积35％加入去离子水、浓缩倍率在9左右时回收率达到95％。     

Hydrophilization of microporous polypropylene Celgard® membranes by the chemical modification technique

Microporous hydrophobic polypropylene (PP) membranes (Celgard® 2400 and 2500) were modified by the chemical modification technique to impart permanent hydrophilicity. The modification was carried out in two stages. In the first stage, the membranes were hydroxylated by treatment with aqueous potassium peroxydisulfate solution under a strong flow of nitrogen. In the second stage, the hydroxylated membranes were subjected to grafting of acrylamide using cerric ammonium nitrate as an initiator. Subsequently, acrylamide grafted PP membranes were partially hydrolyzed to have carboxvl functional groups at the membrane surfaces. Under given experimental conditions the grafting also took place within the pores of the microporous structure of hydrophobic PP Celgard® membranes. Modified membranes exhibited permanently wettable characteristics by aqueous solutions and appeared translucent when immersed in water. Contact angle measurements showed excellent wetting properties with water. In contrast to unmodified Celgard® membrane, the modified membranes exhibit water permeability even after repeated drying. Membranes were further characterized by FTIR and ESCA for the different types of functional groups. © 1996 John Wiley & Sons, Inc.     

基于二维纳米材料的水处理功能膜研究进展

二维纳米材料是制备膜材料中一类重要的掺杂材料或膜构筑单元,也是新型水处理功能膜的研究热点。已有许多研究报道了二维纳米材料通过有序的堆叠和自组装在膜内构建出规整的水通道,可以赋予膜可调控的分离性能,进而实现trade-off效应的突破,被认为是“下一代膜材料”（next-generation membranes）。同时,二维纳米材料的独特片层结构、催化性能及可修饰性可使膜材料获得新的功能,如导电性能、光/电催化性能等。本文综述了近年来基于二维纳米材料的水处理功能膜研究进展,重点介绍了共混法、自组装等制备方法,并总结了此类功能膜在抗污染、膜通量恢复、强化污染物去除、调控盐截留及污染物监测领域的应用。最后对基于二维纳米材料的水处理功能膜发展方向,如限域催化、调控盐分离、监测传感等新兴领域进行了分析和展望。     

Transport properties of graphene oxide nanofiltration membranes: Electrokinetic modeling and experimental validation

There is a need for developing reliable models for water and solute transport in graphene oxide (GO) membranes for advancing their emerging industrial water processing applications. In this direction, we develop predictive transport models for GO and reduced-GO (rGO) membranes over a wide solute concentration range (0.01–0.5 M) and compositions, based on the extended Nernst–Planck transport equations, Donnan equilibrium condition, and solute adsorption models. Some model parameters are obtained by fitting experimental permeation data for water and unary (single-component) aqueous solutions. The model is validated by predicting experimental permeation behavior in binary solutions, which display very different characteristics. Sensitivity analysis of salt rejections as a function of membrane design parameters (pore size and membrane charge density) allows us to infer design targets to achieve high salt rejections. Such models will be useful in accelerating structure-separation property relationships of GO membranes and for separation process design and optimization.     

A new model for mass transfer in direct contact membrane distillation

The mass transfer process in direct contact membrane distillation (DCMD) for three kinds of membranes was measured. Water fluxes at different temperatures and the membrane distillation coefficients (MDC) for each membrane were obtained directly from experimental data. The fact that the MDC values of membranes with larger pore size increase with temperature indicates that Poiseuille flow plays an important role in the process of mass transfer through the membrane. Based on this conclusion, a three-parameter model, named the Knudsen diffusion-molecular diffusion-Poiseuille flow transition (KMPT) model, was developed to predict MDC and water flux for membrane distillation. The parameters of the KMPT model for each membrane employed in this study, by which MDC at various temperatures can be determined, were evaluated by a nonlinear regression. The values of MDC and water fluxes for each membrane predicted by KMPT model agree well with that obtained directly from the experiment results. A large contribution of Poiseuille flow to mass transfer was observed and can be attributed to the distribution of large pores in the membranes. The KMPT model also provides a method for estimation of the effect pore size using the ratio of the MDCs; the ratio of the Poiseuille flow to molecular diffusion MDC provides the best estimation.     

Membrane evaluation for the treatment of acidic clear filtrate

The total effluent load of a paper mill can be significantly decreased by recycling of purified clear filtrate (CF) back to paper-making process. The CF treated with membranes can be reused, for instance, as wire section shower water and in the dilution of chemicals. The main requirements for a membrane in CF treatment are high filtration capacity, high retention of turbidity and low fouling tendency. Previous studies have shown that the regenerated cellulose (RC) ultrafiltration (UF) membrane C30F (current trade name UC030T) is especially suitable for the treatment of paper mill process waters. Every paper-making process is, however, different. Thus, filtration experiments are required in order to find the most optimal membrane for the treatment of a certain process water. In this study the best membrane for the treatment of acidic clear filtrate (ACF) was searched. The performance of the C30F membrane was compared with five UF and three microfiltration (MF) membranes. The results revealed that in addition to the C30F membrane, also some other membranes produced high filtration capacity with ACF (approximately 200 L/(m²h bar)). All the tested membranes also retained over 90% of turbidity. The extremely hydrophilic C30F membrane had, however, lower fouling tendency compared to the other tested membranes. Therefore, it was concluded that the C30F membranes were the best possible membrane for the ACF treatment.     

Analysis of clogging behaviors of diatomaceous ceramic membranes during membrane filtration based upon specific deposit

Fouling behaviors in membrane filtration of dilute suspension of polystyrene latex (PSL) were examined under constant‐pressure conditions using diatomaceous ceramic membranes which are semi‐permeable to the PSL. Flux decline behaviors were evaluated in consideration of the effect of the solid permeation through the membrane. The conventional characteristic filtration equation was modified by applying the Kozeny‐Carman equation to the filtrate flow through the membrane pores. In the model, the porosity and specific surface area of the membrane were represented by unique functions of the solid deposit retained in the membrane pores. The variations of the filtration rate and filtrate volume with the filtration time were accurately described based upon the modified characteristic filtration equation. It was revealed that the extent of the membrane blocking per unit deposit load increased with the decrease in the pore size of the membrane and with decreasing pressure, but was little influenced by the suspension concentration. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Sugar Purification from Enzymatic Rice Straw Hydrolysis Products using Cross-Flow Diafiltration

The sugars produced by enzymatic hydrolysis of rice straw are separated using cross-flow diafiltration in this study. The effects of membrane type, membrane pore size, cross-flow velocity and transmembrane pressure on the filtration flux, sugar rejection, and sugar mass flux transported to the filtrate are discussed. The filtration flux increases with increasing cross-flow velocity or transmembrane pressure. When the membrane made of mixed cellulose ester (MCE) is used, over 70% filtration resistances are caused by the membrane fouling; while the resistance due to virgin membrane is dominant when regenerated cellulose (RC) membranes are used. A force balance model is applied to relate the filtration flux and filtration resistance to operating conditions. The calculated data of filtration flux based on this model agree fairly well with experimental data. In addition, a theoretical model is used to explain the sugar transmission through the cake and membrane pores. The sugar rejection coefficient decreases with increasing cross-flow velocity because of the effect of cake reduction. This effect is more significant when the MCE membrane is used. Comparing the sugar mass flux transported into the filtrate, it is more effective for sugar purification by using 10 kD RC membrane and under higher transmembrane pressures.     

A facile method to functionalize engineering solid membrane supports for rapid and efficient oil–water separation

A facile and low-cost method is developed to functionalize engineering metal membrane supports, such as stainless steel (SS), with epoxy-containing polymer poly(glycidyl methacrylate) (PGMA) to produce a versatile and universal platform for subsequent surface modification. With a PGMA anchoring layer, we have demonstrated that hydrogel particles, such as polyacrylamide-co-poly(acrylic acid) (PAM-co-PAA), can be subsequently grafted to form functional polymer membranes for rapid and efficient oil–water separation. By contact angle and AFM measurement, we have confirmed that PAM-co-PAA hydrogel particle layer grafted on a PGMA-modified SS surface exhibits excellent selectivity as required for liquid–liquid separation, showing high affinity to water but not to oils as an ideal membrane for oil–water separation. To evaluate the separation efficiency, a simple flow-through device is employed to separate free-floating oil from water in the mixture of varied initial oil volume fraction and oil composition. Under substantially high pump flow rate up to 1.3 L/min, PAM-co-PAA hydrogel treated SS mesh can achieve excellent separation efficiency with less than 5% oil or water in the respective filtrate at the flux of as high as 540 m³/(m²·h) and retentate at the flux of 1.95 m³/(m²·h). This separation efficiency is better than, or comparable to, the maximal performance achieved using conventional gravity methods at much lower flow rate. Similar approach could be also adapted to graft superhydrophobic and superoleophilic polymer membranes with PGMA-treated engineering support to separate water from oil.     

Application of microfiltration and ultrafiltration processes to cork processing wastewaters and assessment of the membrane fouling

The filtration of wastewaters generated in the cork industrial process is investigated by using three membranes in tangential filtration laboratory equipment. The three membranes used were two microfiltration membranes with pores sizes of 0.65 and 0.1 μm (DUR-0.65 and DUR-0.1 membranes), and a ultrafiltration membrane with a molecular weight cut-off of 300 kDa (BIO-300K membrane). The water hydraulic permeability was determined for each membrane (values of 860, 248 and 769 L h⁻¹ m⁻² bar⁻¹ were found), and the influence on the permeate flux of the main operating variables, such as transmembrane pressure, feed flow rate, temperature and nature of the membranes, was established. The effectiveness of the different membranes and operating conditions was evaluated by determining the removal obtained for several parameters which measure the global pollutant content of the effluent: COD, absorbance at 254 nm, tannic content, color and ellagic acid, which is selected as a major model pollutant among the different organic compounds present in this wastewater. The values of the corresponding retention coefficients depended on the operating conditions, but in all cases were in the sequence: ellagic acid and color > absorbance at 254 nm > tannic content > COD. Globally, the higher removals were obtained for the BIO-300K membrane at 20 °C, with Q_F = 5.3 L h⁻¹ and TMP = 1.8 bar. Finally, the fouling of the membranes was assessed, and the corresponding mechanism for each membrane was established by fitting the experimental data to various filtration fouling models reported in the literature.