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

Abstract

For the first time pervaporation separation of miscible liquids has been investigated using three and five layered composite membranes. The materials used to construct the different membranes consisted of natural rubber latex (NRL), hydrophilic and/ or hydrophobic polymers, placed sequentially on top of each other. Methyl cellulose (MC) and carboxymethyl cellulose (CMC) were used as hydrophilic polymers to increase the water selectivity of the membrane and in contrast, ultrahigh molecular weight polyethylene (UHMWPE) was used to increase the organic component selectivity in the membranes. Two different miscible liquid solutions were used, including ethanolwater and acetonewater. The composition of organic component in the feed was varied within the range of 20 to 90% w/w. The measured mass and concentration of permeate in the cold trap was related to the pervaporation flux and separation factor. Finally, the proposed mechanisms that may be responsible for enhancing the permeation of water or organic components through the membranes have been discussed. It has been demonstrated that the five layered hydrophilic composite membranes containing MC leads to the best pervaporation separation performance for a feed of 90% concentrated ethanolwater, giving a separation factor of 51 and pervaporation separation index of 6167, as opposed to using a blended membrane which would yield a separation factor of 1.5 and pervaporation separation index of 309