Ethylenediamine-graphene oxide impregnated thin film nanocomposite membrane for the enhanced boron separation from seawater

Abstract

The separation of toxic boron from seawater using nanofiltration (NF) membrane technology is challenging due to the neutral charge associated with boric acid at seawater pH. In this study, the ethylenediamine functionalized Graphene oxide (EDA-GO) derivative is utilized as a nanofiller to coat the active top layer of the NF membrane over the polyethersulfone ultrafiltration support. The coating involved a self-assembly reaction of hydrolyzed trimesic acid (TMA) molecules facilitated by a triethylamine base. The unique hypothesis for coating enabled the –NH2 of EDA-GO to interact with the –COOH of TMA via hydrogen bonding interactions. The rejection shown by the M-0.05 membrane with 0.05wt% loading of EDA-GO towards MgSO4, Na2SO4, and NaCl was >98%, >97%, and 63%, respectively. The same membrane produced water flux in the range of 35-37 L/m2h with the modest significance of the salts on the membrane flux. The M-0.05 membrane showed significantly higher rejection towards boron (>47%) with a flux of 16.7 L/m2h for the beachwell seawater feed owing to the repulsive interaction between the borate ions and -NH2 and -OH groups. The rejection and flux offered by the M-0.05 membrane towards seawater's monovalent and divalent constituents were much higher than the commercial NF-90 and NF-270.