Enhancing antibiotic removal of mixed matrix membranes through electrostatic surface segregation of MIL-101(Fe) catalysts

Abstract

Introducing Fenton-like catalysts into mixed matrix membranes offers two significant advantages— it addresses challenges related to catalyst recovery and reuse while integrating membrane technology with catalytic processes for enhanced pollutant removal. However, achieving a uniform distribution of catalysts within the membrane and maintaining catalytic activity post-blending remains challenging. In this study, positively charged chitosan (CS)-modified MIL-101(Fe) photo-Fenton-like catalysts were incorporated into the casting solution, while negatively charged polyacrylic acid (PAA) was dissolved in the coagulation bath. During the non-solvent induced phase separation (NIPS) of the membrane, the combined effects of hydrophilicity and electrostatic interactions facilitated the migration of MIL-101(Fe) towards the membrane surface, boosting the peroxymonosulfate (PMS) catalytic activity of MIL-101(Fe) for antibiotic degradation. The developed CS@MIL-101(Fe)-PAA/PVDF/PMS/Vis system achieved high removal ratio against tetracycline hydrochloride (TCH) (>99 %), broad working pH range (1–9), and excellent long-term operational stability. Density functional theory (DFT) calculations revealed that PMS exhibited a higher affinity toward the ternary structure, and the activation reaction was thermodynamically favorable and spontaneous. This study offers a novel strategy for the rational design of nanomaterial-based catalytic membranes, bridging the gap between photocatalysis and heterogeneous catalysis, and providing new insights for aquatic environment remediation.