Biofouling mitigation effect of thin film nanocomposite membranes immobilized with laponite mediated metal ions

Biofouling is an inevitable issue that can increase operating cost and reduce treatment efficiency, limiting the widespread application of thin film composite (TFC) membranes. Laponite (Lap) is a synthetic silicate nanoclay with the nanodisk structure, which can be used as a suitable metal ions carrier because it is ion exchangeable and biocompatible. In this work, Ag/Lap, Cu/Lap and Zn/Lap were synthesized by ion exchange method. Subsequently, Lap and metal ion exchanged Lap (M/Lap) were incorporated in polyamide (PA) layers to develop thin film nanocomposite (TFN) membranes by interfacial polymerization. The developed TFN membranes possessed improved water flux and remained a good NaCl rejection rate. Meanwhile, the incorporation of M/Lap endowed the TFN membrane with improved fouling resistance. The TFN-M/Lap membranes showed effective bactericidal properties against both E. coli and S. aureus, particularly the TFN-Ag/Lap membrane with prominent antibacterial properties against E. coli (99.2%) and S. aureus (95.1%). Fluorescence experiment, reactive oxygen species detection and the release of metal ions were also examined. The excellent antibiofouling properties of TFN-M/Lap membranes could be interpreted by cell damage resulting from contact between bacterial and metal ions. Our work provides the potential antibacterial materials and a facile approach to develop novel antibiofouling TFN membranes.