【作者】 杨林；

【导师】 袁其朋；

【作者基本信息】 北京化工大学 ， 生物化工， 2005， 硕士

【摘要】 膜分离技术是近几十年来在分离领域中迅速崛起、应用十分宽广的技术。而膜分离的模型研究是目前国内外膜分离领域研究的热点之一,由于膜分离模型中细孔模型的计算需要液体扩散系数,而很多液体扩散系数模型只适用一定范围,因此,确定适用于特定液体扩散系数的关联方程具有非常重要的意义。 本文将宏观与微观方法相结合,对甲醇溶剂中纳滤膜的传递机理进行研究。先利用分子模拟计算出溶质分子在水和甲醇溶剂中的分子体积,由分子体积结合膜平均孔径和偏离因子计算出膜的反射系数,再利用宏观实验得到纳滤传递及截留性能。在此基础上,研究甲醇溶剂中纳滤膜的传递机理模型。 首先利用分子动力学模拟计算不同浓度中性溶质水溶液中溶质分子的扩散系数,溶质分子主要选用常见的醇类,与各种不同浓度溶液中扩散系数关联方程计算出来的结果进行对照,计算结果表明:对于甲醇和乙醇溶液,Dullien和Asfour方程适用于计算扩散系数D_AB;而对于其它醇类溶液,Leffler和cullinan方程适用于计算扩散系数D_AB。 然后对实验所采用溶质分子的溶剂效应进行了模拟,甲醇溶剂中溶质分子体积均比水相中稍大,这可能是由于甲醇极性比水小,取向力、诱导力和色散力相比水较弱,并且不像水那样存在氢键作用,导致溶质分子之间排斥力较小,则甲醇相中溶质分子体积比水相中大。 接着研究了DK膜和MPF44膜在甲醇溶剂中的传递机理。首先建立了亲水膜的通量模型,对于DK膜,通量模型为Jv=2.153×10-9*ΔP*δ²/（Vmμ）;对于MPF44膜,适用模型为:Jv=0.8452×10-9*ΔP*δ²/（Vmμ）。 最后建立了一种计算膜孔径和偏离因子的方法,计算出DK膜在甲醇溶剂中的膜孔径r=0.976nm,偏离因子S_p=0.215;MPF44膜在水相中的膜孔径（?）=0.974nm,偏离因子S)p=0.111;MPF44膜在甲醇相中的膜孔径（?）=1.025nm,偏离更多还原

【Abstract】 Nanofiltration (NF) is a relatively new membrane process lying between ultrafiltration (UF) and reverse osmosis (RO) and has been extensively applied in water treatment. However, transport and retention data for NF membranes in organic solvents are very limited in the literature, and the mechanism of transport through NF membranes in organic solvent environments is not well understood, which restrict the applications of NF membranes in organic solvents. The calculation of the nanofiltration model needs the liquid diffusion coefficients, but many models of liquid diffusion coefficients has their limitation. Thus it’s very important to select proper model of liquid diffusion coefficients.This thesis primarily investigated the transport mechanism of nanofiltration membranes with methanol solvents by micro and macro-methods. The molecular volume in aqueous solution and in methanol solution was calculated by molecular simulation. Using molecular volume, mean pore size and standard deviation of pore size, the reflection coefficient was calculated. Moreover by macro-experiment,influences of conditions on transport flux of organic solvents permeating through nanofiltration membranes and rejection of the solute in organic solutions are also investigated. Experimental model was established in methanol solution. It will provide theories for development and application of nanofiltration membranes.First of all, in order to testify the diffusion coefficient models of alcohol, molecular dynamics simulation(MD) was employed to calculate the diffusion coefficients of alcohols in the infinite dilute aqueous solution as well as aqueous solution of different concentration of alcohols at 293.15K and 0.1 Mpa. The results show that the equations of Dullien and Asfour can be applied to calculate the diffusion coefficients of methanol and ethanol in aqueous solutions, and that the equations of Leffler and cullinan can be applied to calculate the diffusion coefficients of other alcohol in aqueous solutions.Secondly, The solvent effect of the solute molecule in experiment was simulated. It is possible that the polarity of methanol is smaller than water, and the action between molecules in methanol is smaller than that in water, and there is no hydrogen bond in methanol. Thus the repulsion between the solute molecules is small and the volume of the solute molecule in methanol is larger than that in aqueous solutions.Finally, studies established model of pure solvent permeability coefficient and these parameters. The results showed that permeating更多还原