Self-cleaning PDMS membranes via UV-triggered integration with photocatalytic MOF

Abstract

Photocatalysis dominant mixed matrix membranes have emerged as a promising strategy for enhancing separation performance and solving the membrane fouling. However, the uniform dispersion of photocatalysts within the polymeric matrix and scalability in industrial-scale implementations are still great challenges. The localized agglomeration of photocatalysts not only diminishes degradation efficiency but also generates structural defects that impair membrane separation performance. In this work, a facile UV-triggered integration design of photocatalytic disk-shaped MOF and polydimethylsiloxane (PDMS) was developed to address these issues, enabling rapid (3 min) and scalable fabrication of high-performance self-cleaning nanofiltration (NF) membranes. The UV-triggered thiol-ene reaction between thiol-PDMS and methacrylate-modified polyvinylidene fluoride substrate anchored MOF, thereby suppressing agglomeration. This rapid photopolymerization approach enables uniform distribution of photocatalyst while ensuring scale-up membrane fabrication. Results show that both lab-scale and industrial-scale membranes have superior NF performance with water permeance of 85.73 L m⁻² h⁻¹ bar⁻¹/75.79 L m⁻² h⁻¹ bar⁻¹ and Congo Red rejection of 99.08 %/97.73 % and the industrial-scale membrane demonstrates scalability without compromising selectivity. Furthermore, their excellent separation performance can be recovered over five cycles under sunlight irradiation with no detectable dye residues on the surface, suggesting the robust bonding between disk-shaped MOF and substrate. The photocatalytic degradation mechanism towards dye is also proposed to well understand the self-cleaning process. This work could establish a strategy for fabricating high-performance, self-cleaning and industrial-scale NF membranes, offering new perspectives for sustainable wastewater treatment technologies.