Triple-layered thin film nanocomposite membrane toward enhanced forward osmosis performance

Forward osmosis (FO) has attracted enormous research interests as a prospective low-energy membrane-separation technology in many potential applications such as desalination, wastewater treatment and agricultural irrigation. The novel thin film nanocomposite (TFN) FO membranes have demonstrated great improvement in separation performance and antifouling capacities. As an intermediate layer, carbon nanotubes (CNTs) could control the interfacial polymerization (IP) process to obtain an ultrathin and dense polyamide (PA) selective layer. Silver phosphate loaded acidified graphitic carbon nitride (aCN/AP) exhibited excellent nanofiller properties, including excellent aqueous dispersity, confined mass transfer, and outstanding bacteriostasis. In view of this, we fabricated TFN FO membranes with CNT as interlayer and aCN/AP as nanofillers into PA layer. Improved hydrophilic and enhanced negatively surface charges were obtained with the incorporation of aCN/AP. The optimal TFN-aCN/AP membrane possessed a higher water flux of 67.0 L m−2 h−1 accompanied with a reverse salt flux lower than 3.0 g m−2 h−1 by using 1 M NaCl as draw solution. Besides, the TFN-aCN/AP membrane showed excellent antibacterial property against both gram-negative E.coli and gram-positive S.aureus with a sterilization rate of 99.0% and 92.0%, respectively. This work provides a new strategy to fabricate novel TFN FO membranes with high permselectivity and excellent antibacterial capacities.