Investigating mechanism of enhanced anti-fouling performance of MXene modified Janus MD membrane by XDLVO theory combined with surface elemental integration method

Abstract

Organic membrane fouling is a major obstacle to the application of membrane distillation in low surface tension wastewater treatment. Membrane modification might be an effective way to mitigate membrane fouling. This study mainly explored the mechanism of enhanced anti-fouling performance of the MXene modified PVDF membrane by applying XDLVO theory combined with surface elemental integration (SEI) method. The rough membrane surfaces were first reconstructed using fractal function. Then, the interaction energy between low surface tension substances and the membranes before and after modification was calculated. The results showed that oil droplets and surfactant fouling were mainly caused by hydrophobic attraction due to Lewis acid-base (AB) interaction energy. By modifying the virgin PVDF membrane with MXene nanoparticles, the polar component of membrane surface tension (γAB) increased significantly, so that the interaction energy between all contaminants and membrane surface changed from attraction to repulsion. In addition, roughness weakened the interaction energy between contaminants and membrane surface but significantly lengthened the range of interaction distance, which together determined the ability of the membrane to attract or repel the contaminants. These findings may improve the understanding of the structure-effect relationship between membrane modification and anti-fouling ability, and provide new insights into the membrane modification for MD.