Sulfonated polybenzimidazole membranes for pervaporation dehydration of acetic acid

Abstract

Abstract In this study, a novel sulfonated polybenzimidazole (SPBI) membrane has been developed and investigated for pervaporation dehydration of acetic acid, via a two-step sulfonation modification technique—sulfonation with sulfuric acid followed by a thermal treatment at 450 °C. Both steps are found indispensible in order to produce a stable SPBI membrane with enhanced acid resistance and superior separation performance. Effects of the sulfuric acid concentration and thermal treatment duration have been investigated and found to have significant impact on the pervaporation performance of the resultant SPBI membranes. Various characterizations (FTIR, XPS, TGA and XRD) are employed to elucidate the physicochemical changes of membranes as a function of chemical and thermal modifications. In addition, effects of pervaporation temperature and feed composition are studied not only in terms of flux and separation factor, but also of membrane intrinsic permeance and selectivity. The best pervaporation performance of the SPBI membrane has a flux of 207 g/m 2 /h and a separation factor of 5461 for dehydration of a 50/50 wt% acetic acid/water feed solution at 60 °C, which not only outperforms the conventional distillation process, but also surpasses most other polymeric pervaporation membranes reported in literature. It is therefore believed that the novel developed SPBI membrane may have great potential for pervaporation dehydration of acidic organics, as well as other applications that demand acid-proof materials.