Inhibiting Polyamide Intrusion of Thin Film Composite Membranes: Strategies and Environmental Implications

Abstract

Thin film composite polyamide (TFC)nanofiltration (NF)membranesrepresent extensive applications at the water-energy-environment nexus,which motivates unremitting efforts to explore membranes with higherperformance. Intrusion of polyamide into substrate pores greatly restrictsthe overall membrane permeance because of the excessive hydraulicresistance, while the effective inhibition of intrusion remains technicallychallenging. Herein, we propose a synergetic regulation strategy ofpore size and surface chemical composition of the substrate to optimizeselective layer structure, achieving the inhibition of polyamide intrusioneffective for the membrane separation performance enhancement. Althoughreducing the pore size of the substrate prevented polyamide intrusionat the intrapore, the membrane permeance was adversely affected dueto the exacerbated "funnel effect". Optimizing the polyamidestructure via surface chemical modification of the substrate, wherereactive amino sites were in situ introduced by the ammonolysis ofpolyethersulfone substrate, allowed for maximum membrane permeancewithout reducing the substrate pore size. The optimal membrane exhibitedexcellent water permeance, ion selectivity, and emerging contaminantsremoval capability. The accurate optimization of selective layer isanticipated to provide a new avenue for the state-of-the-art membranefabrication, which opens opportunities for promoting more efficientmembrane-based water treatment applications.NF membrane prepared with the polyamideintrusion inhibitionstrategy reduces hydraulic resistance and optimizes polyamide structure,achieving enhanced membrane separation performance and emerging contaminantremoval.