Facile in situ decorating polyacrylonitrile membranes using polyoxometalates for enhanced separation performance

Although membrane-based separations play an increasing role in alleviating the global water crisis, the practical usage is inevitably hindered by intrinsic membrane limitations such as the trade-off relation between permeability and selectivity, organic and biofouling propensity, and weak chemical stability during chemical washing. In this study, we reported a novel composite membrane fabricated by in situ decorating polyacrylonitrile (PAN) membrane using phosphomolybdic acid (PMo12) via a one-pot hydrothermal process. Benefiting from the superior hydrophilicity and negative charge of the PMo12, the separation performance of the modified membranes was significantly enhanced. By tuning the coordination temperatures, the obtained optimal PMo12-modified membrane exhibited a flux increment of ca. 50% and an enhanced BSA rejection from 95.1% to 97.8%, due to the enhanced hydrophilicity and shrank pore sizes. The improved hydrophilicity and the elevated surface negative charges additionally contributed to the enhanced antifouling properties of the PMo12-modified membrane toward negatively charged pollutants both in dynamic and static fouling processes. Furthermore, PMo12-modified membranes are capable of maintaining a high level of separation properties even after chemically rinsed with strong acidic, oxidizing, basic solutions, respectively. More importantly, a strong biocidal activity of 95.7% against E. coli was attained for the modified membranes due to the sterilization ability of PMo12. This work provides a new pathway to fabricate chemically stable membranes with elevated separation performance and antifouling property, which has a great potential for large-scale membrane manufacture.