Non-polyamide nanofiltration membranes with low MWCO prepared by combining the catechol-amine chemistry and the chemistry of amino-silane coupling agents

The present work provides an efficient strategy to prepare mussel-inspired nanofiltration membranes with lower MWCO, via combining the catechol-amine chemistry and the chemistry of amino-silane coupling agents. The membranes were synthesized by stepwise depositing tannic acid (TA) and pre-hydrolyzed 3-aminopropyltriethoxysilane (APTES) on the PSF support. TA adsorbed on the polysulfone (PSF) support via hydrogen bonding. The pre-hydrolyzed APTES self-polymerized and reacted with TA, forming a crosslinked network through the Michael addition/Schiff base reactions. The membrane performance was tailored by controlling the hydrolysis degree of APTES. At optimal conditions, the APTES-TA/PSF membrane with MWCO of 200 Da and water permeance of 11 Lm−2h−1bar−1 was fabricated. The salt rejections toward Na2SO4 and NaCl were around 90% and 20% respectively. The continuous prolonged filtration showed the membrane had good filtration stability. Compared with previously reported mussel-inspired and polyphenol membranes, the present membrane had a much lower MWCO and higher permeance. The membrane can efficiently remove typical pharmaceuticals with molecular weight from 200 to 400 Da, indicating this type of membrane has promising prospects in trace-organic contaminated wastewater treatment.