Two-dimensional Cu-FeTCPP nanozyme incorporated loose nanofiltration membrane with self-cleaning property for dye/salt separation

Abstract

Wastewater discharged from the textile industry contains large amounts of dyes and salts, causing serious pollution to the environment. Loose nanofiltration (LNF) membranes offer a promising solution for dye/salt separation. However, membrane fouling is a critical issue affecting the membrane performance. Here, polyether amine (PEA) is used as the aqueous monomer for interfacial polymerization to prepare a polyamide (PA) LNF membrane, and peroxidase-like Cu-FeTCPP nanosheets are embedded into the PA layer to develop the Nanozyme@PA membrane. The nanozyme-incorporated membrane has a thinner and enhanced porous active layer than PA membrane, resulting in higher water permeance (maximum of 80.7 L·m⁻²·h⁻²·bar⁻¹), notable rejection of dyes (CR, >99.2 %) but low rejection of inorganic ions (NaCl, <6.4 %). The optimum dye/salt separation factor of Nanozyme@PA reaches 218.7. The loaded nanozyme can catalyze the degradation of dyes adsorbed on the membrane surface in the presence of hydrogen peroxide within 10 min, without the need for special operation, enabling the recovery of water permeance. This nanozyme functionalized LNF membrane with good permeability, selectivity and self-cleaning offers an efficient approach to dye wastewater treatment as well as an insight for membrane fabrication assisted by two-dimensional nanozyme.