Synthesis,characterization and application of PVA/ionic liquid mixed matrix membranes for pervaporation dehydration of isopropanol

In this study,polyvinyl alcohol(PVA)–ionic liquid(IL) membranes were prepared for the separation of isopropyl alcohol(IPA)–water azeotropic mixtures by pervaporation.PVA-IL composite membranes were prepared by simple solvent evaporation method using four ILs,viz.,1-n-butyl-3-methylimidazolium chloride(BMIMCl),1-hexyl-3-methylimidazolium chloride(HMIMCl),1-hexyl-3-methylimidazolium tetra fluoroborate(HMIMBF4) and 1-octyl-3-methylimidazolium chloride(OMIMCl).Three ILs were used to study the effect of alkyl chain on the pervaporation performance.The study had focused on the effect feed water concentration from 10%–40%and effect of feed temperature from 50–80°C.Physiochemical properties of all the membranes were studied using Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and contact angle measurement.The Arrhenius activation energies for permeation were estimated to be in the range 4–12 kJ·mol-1 from the temperature dependent permeation values.

聚乙烯醇-海藻酸钠共混中空纤维复合膜用于异丙醇脱水

制备了以聚砜(PS)中空纤维超滤膜为底膜的聚乙烯醇(PVA)-海藻酸钠(SA)共混复合膜,并用于异丙醇脱水的研究。考察了PVA/SA配比、交联剂种类和浓度以及渗透汽化实验中的操作条件对膜性能的影响。在PVA/SA质量比为4/1、料液温度45℃、料液中异丙醇质量分数为90%时,复合膜的通量和分离因子分别为427g/(m2·h)和1727,并且根据实验数据和Arrhenius经验方程式,计算得出异丙醇渗透活化能为17 42kJ/mol。

氧化石墨烯量子点改性海藻酸钠复合杂化膜的制备

自制氧化石墨烯量子点(GOQDs)分散于海藻酸钠(SA)溶液中,涂覆在多孔尼龙膜支撑层上,制备GOQDs改性SA复合杂化膜.研究了GOQDs的加入对膜结构、形貌、表面亲水性、溶胀性和渗透汽化性能的影响.结果表明,复合杂化膜对异丙醇溶液具有明显的渗透汽化脱水作用,GOQDs质量分数为2%的膜性能最优,该膜对温度为50℃,水质量分数为10%的异丙醇溶液的渗透通量和分离因子分别为(1130±51)g/(m^(2)·h)、2241±73,分别是海藻酸钠膜的1.41倍和5.90倍,渗透汽化分离指数为2.53×10^(6) g/(m^(2)·h),比海藻酸钠膜提高了8倍.操作温度的升高会提高膜的分离因子和通量,进料液浓度的增大会使膜的通量显著变大.过量的GOQDs不会对膜渗透汽化脱水产生显著的阻碍作用.

利用膜脱水回收离子液体的研究

利用膜反应器对比在不同的工况下反渗透膜和渗透气化膜脱水回收[Emim][OAc]离子液体的效果。结果表明,反渗透膜对于低浓度离子液体具有较高的截留效果,而随着离子液体浓度的增加,透过反渗透膜离子液体的浓度增加,脱水效果变差,并且渗透量也从原来浓度为2%(wt)的[Emim][OAc]的9kg/(m^2·h)降低到了8%(wt)时的1.69kg/(m^2·h)。渗透气化膜在温度为100℃、流速为10 mL/min条件下,内循环62小时,通量从最开始的0.434 kg/(m^2·h)到0.302 kg/(m^2·h),保持略微下降的趋势,而离子液体的浓度从初始的20%(wt)上升到50%(wt)。表明了利用渗透气化膜对于IL-H_2O脱水的可行性。对IL离子液体的脱水回收具有一定的指导意义。