Polyol grafted thin film nanocomposite membrane: Enhanced pervaporation performance for isopropanol dehydration

Abstract

Isopropanol is used as a cleaning agents especially in the semiconductor industry. Thus, recycling, and purifying alcohol can reduce the overall cost of production. To improve the separation performance of the thin-film nanocomposite (TFN) membrane, nanozeolite (NZ) was embedded in polyamide layer followed by post-treatment of polyols. The polyamide layer was fabricated through interfacial polymerization of diethylenetriamine (DETA) and trimesoyl chloride (TMC). NZ was dispersed in TMC in order to be embedded on the separation layer. Afterwards, the membrane was simultaneously post-treated using polyols. Different types of polyols were introduced: d-sorbitol (DST), erythritol (ERT), and pentaerythritol (PET). A higher number of hydroxyl groups can provide a denser separation layer. Their chemical structures also affects the reaction rate, where more linear structures (DST and ERT) had better reaction and crosslinking with acyl chloride. High reaction rate of DST gives the roughest surface and high crosslinking degree. Compared to other polyols, Using DST in post-treatment exhibited the highest separation performance. It had a permeation flux of 3,098 g·m−2·h−1 and 99.9 wt% water concentration in permeate (feed = 70 wt% aqueous isopropanol solution at 25℃). Therefore, post-treatment using polyols can further enhance the separation efficiency of TFN membranes with a stable performance over a long period of time.