将渗透汽化应用于醇/水体系的分离,具有诸多显著的优势。然而,目前的研究大都基于二元体系,而实际的应用体系是多元的,还包含少量无机盐和糖类等,它们的存在对膜的性能具有一定的影响。本文研究了NaCl、KCl和MgCl23种无机盐的加入对聚二甲基硅氧烷(PDMS)/陶瓷复合膜渗透汽化性能的影响。结果表明,在313 K,无机盐的加入使复合膜的分离因子和通量均有所提高。其中二价盐MgCl2对渗透汽化性能的影响最为显著,分离因子最大提高到醇/水体系的2.8倍。而一价盐NaCl和KCl的加入,使分离因子分别提高为醇/水体系的2.5倍和2.4倍。同时借助于Setschenow扩展方程计算了乙醇活度,对实验结果进行了初步的解释。
There are many significant advantages when pervaporation is used in the separation of ethanol/ water system. The current studied systems are mainly the binary feed mixtures, but the real systems are commonly multi-component mixtures and might include inorganic salts and sugars, which may have effects on the pervaporation performance of the membrane. In this work the effects of three inorganic salts (NaCl, KCl and MgCl2) on the pervaporation performance of polydimethylsiloxane (PDMS) /ceramic composite membranes were studied. The results showed that the addition of inorganic salts caused simultaneously the increase of the flux and the separation factor. Among the three salts, MgCl2had the most notable effect on the pervaporation performance. The separation factors of the tertiary system were 2.8, 2.5 and 2.4 times of those of the ethanol/water binary system for MgC12, NaCl and KCl respectively. The experimental phenomena could be explained by the ethanol activity, which was calculated by using the Setschenow empirical equation.