Hydrolysis co-deposition of bio-inspired hybrid hydrophilic network antifouling loose nanofiltration membrane for effective dye/salt separation

Abstract

Nowadays, loose nanofiltration (LNF) membranes with effective filtration performance toward textile wastewater have drawn intensive attention. In this work, a high-performance LNF membrane was prepared via fast co-deposition of bio-inspired TA-based hydrophilic coating with in-situ hydrolysis of tetra butyl titanate (TBT) on polyethersulfone (PES) substrate. Various additives containing amino acid (l(+)-Arginine) and silane coupling agent (KH792) were mixed in the coating solution and researched their synergistic effects during membrane preparation. In-situ growth of TiO2 and co-deposition of TA-based coating endowed the LNF membrane with a uniformly rough hydrophilic surface. Therefore, the optimal LNF membrane showed a significantly high pure water permeability (92.9 L m−2 h−1·bar−1) with high rejection (>99.0 %) in treating negatively charged dyes including Eriochrome Black T, Congo Red, Chlorazol Black T, and Coomassie Brilliant Blue G. Meanwhile, low rejections for inorganic salts (Na2SO4: 7.9 %, NaCl: 2.5 %, MgCl2: 2.8 %, MgSO4: 7.3 %) were reached, and it kept distinguished separation performance in dealing with highly saline dye wastewater (containing 50 g L−1 NaCl and Na2SO4, respectively). Beyond that, the membrane had excellent antifouling properties with low flux decline of multiple model pollutants and stability during separation dye/salt mixture, which revealed the LNF membrane prepared promising potential in actual textile wastewater treatment.