Amine-functionalized biochar/cellulose acetate hybrid membranes for sustainable municipal wastewater treatment

Abstract The valorization of agricultural waste into functional materials offers a sustainable route for developing advanced water treatment technologies. In this study, microalgae biomass was converted into biochar and subsequently functionalized with amine groups via a one-step mussel-inspired polymerization and Schiff-base addition reaction. The resulting novel amine-functionalized biochar (AFBC) was incorporated into cellulose acetate (CA) membranes using the nonsolvent-induced phase separation (NIPS) method to fabricate hybrid ultrafiltration membranes. Comprehensive structural and physicochemical analyses confirmed the successful functionalization of the biochar and its uniform distribution within the CA matrix. AFBC incorporation significantly enhanced the membrane's hydrophilicity, porosity, and surface charge, leading to improved rejection of natural organic matter (NOM). The membrane containing 4 wt.% AFBC achieved a flux of 169.1 LMH and 64.1% NOM removal efficacy during municipal wastewater filtration, outperforming the pristine CA membrane (81.8 LMH, 31.1% removal). Moreover, the modified membrane demonstrated complete bacterial removal, partial elimination of other contaminants, and a high flux recovery ratio (82.7%), indicating excellent antifouling properties. These findings establish AFBC as a promising sustainable filler for the development of high-performance hybrid membranes for eco-friendly municipal wastewater treatment. Graphical Abstract