Construction of highly hydrophilic PAN-co-IA/CNTs@TA composite membrane with large flux and high retention for purification of dye wastewater

The rising pollution caused by dye industrial wastewater has led to irreversible destruction of the environment and human health. Hence, there is an urgent need to construct hydrophilic separation membranes possessing high flux and retention to be used in water treatment. To solve this problem, polyacrylonitrile-co-itaconic acid (PAN-co-IA) copolymer was prepared as matrix, tannic acid (TA) encapsulated carbon nanotubes (CNTs) named as CNTs@TA was used as nano-modifier to design the PAN-co-IA/CNTs@TA composite flat membrane by the non-solvent-induced phase separation technique. The copolymerization of IA improved the hydrophilicity of PAN, in addition, the hydrogen bonding formation between IA and TA on the surface of CNTs ensured the stable existence of CNTs@TA particles in the composite membrane. At the same time, the π-π bonds between TA and CNTs avoided the loss of TA during the wastewater separation process. The introduction of IA, TA, and CNTs endowed the PAN-co-IA/CNTs@TA composite membrane with excellent hydrophilicity and double-layer finger pore structure, which achieved its high pure water flux of 3102.63 Lm-2h-1. What's more, the PAN-co-IA/CNTs@TA composite membrane behaved large flux (>1600 Lm-2h-1) and high retention (>97 %) for various cationic dye wastewater based on the electrostatic adsorption mechanism. In addition, the high hydrophilicity and the reinforcing effect of CNTs endowed PAN-co-IA/CNTs@TA membrane with excellent cycling stability. Therefore, this research provides a simple and convenient dye wastewater purification strategy with promising application prospects.