Development of polybenzoxazine membranes for ethanol-water separation via pervaporation

Polybenzoxazine membranes have been successfully synthesized from bisphenol-A, formaldehyde, and three different types of diamines: hexa-methylenediamine (hda), tetraethylenepentamine (tepa), and tetraethylenetriamine (teta) via a facile quasi-solventless method. To study the possibility of using polybenzoxazine membranes in a pervaporation system for ethanol-water separation, the sorption and swelling behaviors of these membranes were investigated. When hda was used as a reactant, the resulting polybenzoxazine membranes showed the best service time and interestingly only water permeated the membranes under the studied operation conditions. The total permeation flux was found to be 1.52 kg/m(2)h and the separation factor was higher than 10,000. Additionally, an increased permeation flux was achieved by raising the temperature of the feed solution and decreasing the membrane thickness. The optimum conditions for this study were 70 degrees C for the feed mixtures when a 200 mu m thick was used. (C) 2010 Elsevier B.V. All rights reserved.