Separation of organic mixtures by pervaporation using crosslinked and filled rubber membranes

Natural rubber (NR) and poly(styrene-co-butadiene) rubber (SBR) were crosslinked chemically with sulfur and accelerator by efficient vulcanization. These were then compounded for physical crosslinking with high abrasion carbon black filler (grade N330) with three different doses, i.e. 5, 10 and 20 phr to obtain three filled membranes from each of these two rubbers (NR-5, NR-10 and NR-20 and SBR-5, SBR-10 and SBR-20). These six filled rubber membranes were used for pervaporative separation of toluene–methanol mixtures up to 11 wt% of toluene in feed. It has been found that with increase in filler doses from membrane-5 to membrane-20, the selectivities and mechanical properties of the membranes increase. All of these membranes showed reasonably good range of flux (20.814 g/m2 h for SBR-5 to 10.26 g/m2 h for NR-20) and separation factor (286.4 for NR-5 to 183.7 for SBR-5) for 0.55 wt% of toluene in feed. Among these membranes NR-20 and SBR-20 with highest crosslink density showed maximum separation factor for toluene along with good flux. It has also been found that for comparable crosslink density NR membranes showed better separation factor than SBR membranes.