Rejection of an emerging small neutral organic micropollutant by in-situ nanofiltration membrane modification for water treatment.

Abstract

Nanofiltration (NF) membranes are recognized for their potential in removing organic micropollutants (OMPs). However, the limited efficiency of commercial NF membranes in removing small and neutral emerging OMPs has impeded its wide use. This study explores the effectiveness of in-situ modification of commercial NF270 membranes using two monomers for the removal of 1H-benzotriazole (BTA). For the first time, this work investigates the physicochemical properties of commercial NF270 membranes grafted with these two monomers, 3-(trimethoxysilyl)propyl methacrylate and 2-(diethylamino)ethyl methacrylate, using different surface characterization techniques. The study also evaluates the performance of both unmodified and modified membranes in the rejection of BTA and compares the results with state-of-the-art monomers. The 2-(diethylamino)ethyl methacrylate-grafted membranes show a modest enhancement of 12 % in BTA rejection. In contrast, the 3-(trimethoxysilyl)propyl methacrylate-modified membranes exhibit a remarkable 107 % improvement in BTA rejection compared to the virgin NF270 membrane, achieving the highest increase in OMP removal among current state-of-the-art monomer-modified membranes reported in previous research. This approach effectively removes BTA primarily through the mechanisms of size exclusion and hydrophobic interactions. This research presents a comprehensive strategy for surface modification of NF membranes, offering potential improvements in the rejection of small and neutral OMPs for water treatment.