Separation of textile wastewater using a highly permeable resveratrol-based loose nanofiltration membrane with excellent anti-fouling performance

A precise separation of organic dyes and inorganic salts is a prerequisite for zero liquid discharge of saline textile wastewater. The development of loose nanofiltration (LNF) membranes with customized nanoscale pores and high water permeance is expected to address this challenge. Herein, a new LNF membrane is reported, fabricated via a scalable interfacial polymerization (IP) approach between resveratrol and trimesoyl chloride (TMC) on a Kevlar substrate. The optimal resveratrol/TMC membrane exhibited an ultra-high pure water permeance (121.1 L-1 m(-2)h(-1) bar(-1)), high dye rejection (99.4% for 200 ppm of Congo Red), and low salt rejection (4.2% for NaCl and 9.8% for Na2SO4). The chemical compositions, surface properties, and morphologies of the LNF membranes were characterized to elucidate their structure-property-performance relationships. The homogeneous diffusion of resveratrol to the water/hexane interface and the appropriate stoichiometry of the two monomers contribute to the formation of an ultra-thin (35-45 nm) and hydrophilic composite membrane, which allows the membrane to attain a high water permeance. The LNF membrane additionally maintains excellent anti-fouling properties during filtration of organic dye solutions, primarily as a result of the high hydrophilicity, negative charge density, and smoothness of the membrane surface. Importantly, the novel LNF membrane also retains stability after washing with ethanol and acetone, owing to the cross-linked polyphenol ester and the rigid phenyl backbone of the membrane surface. These results reveal the huge potential of applying resveratrol-based LNF membranes for the treatment of saline textile wastewater.