A photo-bactericidal thin film composite membrane for forward osmosis

Abstract

Modification of the membrane surface with bactericidal moieties is the most effective way to address the microbial fouling issue in membrane technology. Here, we introduce a new design for anti-microbial fouling membranes, where the membrane could readily use sunlight to effectively inactivate bacteria on the membrane surface. The key concept in our design is to use a cheap and efficient photosensitizer – porphyrin – to modify the surface of a thin film composite (TFC) membrane, leading to the formation of a porphyrin-grafted TFC membrane (or Por-TFC in short). The as-fabricated Por-TFC membrane has good chemical and photo stability owing to the strong covalent bond between the grafted porphyrin and the TFC membrane. Interestingly, upon sunlight radiation, the as-grafted porphyrin can effectively produce singlet oxygen or other reactive oxygen species, which are highly cytotoxic to bacteria, thus addressing the challenging biofouling issue in membrane technology. In addition, the porphyrin molecules grafted on the TFC membrane can also improve the membrane performance in the forward osmosis (FO) process. The present work suggests encouraging applications of the as-designed photo-bactericidal TFC membrane in the FO process.