Two-dimensional g-C3N4-based photo-Fenton-like membrane: Enhanced water transport and in-situ self-cleaning by citric acid-Fe (III) complex intercalation

As a semiconductor material with layered structure, g-C3N4 is an ideal material for constructing two-dimensional photocatalytic self-cleaning membranes. However, the tight interlayer structure formed during the stacking of nanosheets can cause slow water penetration, reduction of catalytic sites, and rapid recombination of photo- generated carriers. In this study, an effective strategy is proposed to construct an enhanced photo-Fenton-like self-cleaning membrane (CN@CS-CA center dot Fe), which includes chitosan (CS) surface functionalization and hydrogen-bond-mediated intercalation of citric acid-Fe (III) complex (CA center dot Fe). The CS can make the membrane structure more regular, and the CA center dot Fe network can effectively expand the interlayer spacing of g-C3N4 membrane. Molecular dynamics (MD) simulation results show that the expansion of interlayer spacing can provide additional channels for water molecule transport and accelerate water transport rate. The CN@CS-CA center dot Fe membrane can achieve high dye rejection (95.9 %) and fast water transport process (230.5 L center dot m-2 center dot h-1 center dot bar- 1 ). Under light excitation, the inherent photocatalytic properties of g-C3N4 are coupled with the photo-Fenton effect of CA center dot Fe to rapidly degrade membrane fouling in situ, giving the CN@CS-CA center dot Fe membrane a stable separation- fouling-self-cleaning regeneration cycle performance.