Development of methyl cellulose and carboxymethyl cellulose composite membranes for the separation of miscible liquids by applying pervaporation technique

摘要

For the first time pervaporation separation of miscible liquids has been investigated usingthree and five layered composite membranes. The materials used to construct the different membranesconsisted of natural rubber latex (NRL), hydrophilic and/ or hydrophobic polymers, placedsequentially on top of each other. Methyl cellulose (MC) and carboxymethyl cellulose (CMC) wereused as hydrophilic polymers to increase the water selectivity of the membrane and in contrast, ultrahighmolecular weight polyethylene (UHMWPE) was used to increase the organic componentselectivity in the membranes. Two different miscible liquid solutions were used, including ethanolwaterand acetonewater.The composition of organic component in the feed was varied within therange of 20 to 90% w/w. The measured mass and concentration of permeate in the cold trap wasrelated to the pervaporation flux and separation factor. Finally, the proposed mechanisms that may beresponsible for enhancing the permeation of water or organic components through the membraneshave been discussed. It has been demonstrated that the five layered hydrophilic composite membranescontaining MC leads to the best pervaporation separation performance for a feed of 90% concentratedethanolwater,giving a separation factor of 51 and pervaporation separation index of 6167, asopposed to using a blended membrane which would yield a separation factor of 1.5 and pervaporationseparation index of 309.