Abstract
Polybenzoxazine (PBz) membranes with modification have been used for liquid-liquid pervaporation separation by different feed concentrations and different feed temperatures to investigate the separation performance and the membrane stability in this research. We used many methods to make PBz membrane more hydrophilic in order to increase the pervaporation separation flux. We tried PBz to blend with not only hydrophilic materials such as chitosan, poly(ethyleneimine) and tetraethylenepentamine (TEPA) but also halides like p-xylylene dichloride and 1,3-dibromopropane which made PBz quaternized to increase the membrane hydrophilicity. But these methods didn’t work in the increase of the pervaporation separation flux. It shows that immersing the PBz membrane in a basic NaOH aqueous solution made it more hydrophilic and showed higher pervaporation separation flux. However, the surface modification was not appropriate for isopropanol aqueous solutions system. The PBz-10 membrane shows high pervaporation separation flux which are about 1.2-fold to 1.7-fold of the value measured with the PBz membrane without decreasing the separation performance at the system of tetrahydrofuran aqueous solutions. In this work, the PBz membrane and the PBz-10 membrane are effective for pervaporation dehydration on tetrahydrofuran aqueous solutions in a wide concentration range of 30 to 90 wt% and a wide temperature range of 25 to 55℃.