Polybenzoxazine-based membrane for ethanol-water seperation via pervaporation

Abstract

Nowadays, alternative renewable energy has become an attractive choice of fuel due to increasing in price of fuel, serious shortage of fossil resources and environmental concern. One of the most common renewable biofuels today is bioethanol (gasohol). Generally, ethanol used in gasohol is derived from the distillation process that requires high energy consumption and high operating cost. Therefore, other techniques are preferred in order to reduce the gasohol production cost. Pervaporation (PV) is especially attractive technique due to its higher separation efficiency and potential savings in capital and energy consumption. In this work, cardanol-modified polybenzoxazine (PBZ) membrane has been successfully prepared by mixing cardanol into benzoxazine prepolymer to prevent membrane swelling during ethanol-water separation. The maximum cardanol content was 5 wt. % because at higher concentrations, cardanol could not mix homogeneously with the benzoxazine precursor. The total permeation flux of this membrane with a 200 µm thickness was 0.33 kg/m2h and the separation factor was higher than 10,000 when 50 wt.% of ethanol was used as a feed. Additionally, an increase in permeation flux was achieved by adding NaA into the system since more water could pass through the membrane due to the porosity of the membranes increased as increasing NaA contents. However, the separation factor was not affected. When NaA was incorporated (up to 5 wt.%), the total permeation flux was increased to 0.98 kg/m2h, while the seperation factor was still higher than 10,000.