Graphene nanofiltration membrane intercalated with AgNP@g-C3N4 for efficient water purification and photocatalytic self-cleaning performance

Low water flux and heavy membrane fouling hinder the use of graphene-based membranes for water purification and molecular sieving. To the end, a novel graphene-based membrane, intercalated with Ag nanoparticles anchored g-C 3 N 4 (AgNP@g-C 3 N 4 ) as pillars and photocatalysts, was fabricated through a mixed-dimensional assembly strategy. The uniform loading of Ag nanoparticles on g-C 3 N 4 can greatly improve the photocatalytic ability of g-C 3 N 4 while creating more water transport channels between reduced graphene oxide (rGO) and g-C 3 N 4 laminates. The resultant rGO/AgNP@g-C 3 N 4 nanofiltration membrane displayed efficient water permeability, superior photocatalytic self-cleaning performance, and owned excellent flexibility and structural stability. The water permeability of the rGO/AgNP@g-C 3 N 4 membrane was considerably improved (210.9 L∙m −2 ∙h −1 ∙bar −1 ) compared to the pure rGO membrane (78.4 L∙m −2 ∙h −1 ∙bar −1 ) due to the larger interlayer spacing and rough surface. After 1 h of visible light irradiation, the decrease of flux produced by pollutant molecule adsorption can recover with a ultrahigh flux recovery ratio (FRR) of 98.1%. Moreover, the high flux of the rGO/AgNP@g-C 3 N 4 membrane remained stable in a cross-flow photocatalytic nanofiltration device. Membrane separation, photocatalytic regeneration, and pollutant degradation by ·OH and ·O 2 − radicals are proposed as effective cooperation mechanisms.