Abstract
High permeance combined with high salt/dye separation efficiency is a prerequisite for achieving zero-liquid-discharge treatment of saline textile wastewater by membrane technology. Thin-film nanocomposite (TFN) membranes incorporating porous nanoparticles offer a promising route to overcome the permeability-selectivity trade-off of conventional polymer membranes. In this study, a vacuum-assisted method was used to co-blend ZIF-67 and SiO(2) nanoparticles, while branched polyethyleneimine (PEI) served as a cross-linking bridge, resulting in a high-performance TFN membrane for salt/dye separation. Acting as a molecular connector, PEI coordinated with ZIF-67 through metal-amine complexation and simultaneously formed hydrogen bonds with surface hydroxyl groups on SiO(2), thereby linking ZIF-67 and SiO(2). The resulting membrane exhibited good hydrophilicity and excellent dye separation performance (water flux = 359.8 L m(-2) h(-1) bar(-1); Congo Red rejection = 99.2%) as well as outstanding selectivity in dye/salt mixtures (Congo Red/MgCl(2) selectivity of 1094). The optimal ZIF@SiO(2)-PEI membrane maintained stable dye rejection over a wide range of trans-membrane pressures, initial concentrations, and pH values. These results reveal the huge potential of applying the ZIF@SiO(2)-PEI TFN membranes for resource recovery in sustainable textile wastewater systems.