Preparation and antifouling property improvement of Tröger's base polymer ultrafiltration membrane

Tröger's base (TB) polymers have received increasing interest for different potential applications in the field of membrane techniques. In this study, a TB polymer was used for the first time to prepare ultrafiltration (UF) membrane and its antifouling property was enhanced through membrane quaternization process. The pure water flux of TB UF membrane prepared from NMP solution was 448 L m−2 h−1 with a high rejection for solute (97% for bovine serum albumin (BSA) and 90% for humica acid). The high permeability of TB UF membrane was related to its high overall porosity, while the high separation property was attributed to its small average pore size on the surface as evidenced by SEM observations. Due to the presence of tertiary amine groups, the TB membrane was further functionalized by the quaternization with methyl iodide. Surprisingly, the antifouling property of quaternized TB (QTB)membrane was improved when using BSA as a model foulant when compared to the TB membrane. The flux recovery ratio of QTB membrane was enhanced from 55% to 91% when the quaternization degree was 10%. This may be attributed to the enhanced hydrophilicity of membrane surface after the quaternization of tertiary amino groups. More importantly,QTB membrane showed higher pure water flux, BSA solution flux and flux recovery ratio than the commercial PAN, PES, PSf and PVDF membranes through a three-cycle of membrane fouling test. Moreover, the effect of polymer concentration in the casting solution, type of solvent and coagulation bath temperature on the UF membrane morphology and ultrafiltration performance were investigated.