Biocatalytic nanomotor-assisted ultrafiltration membrane system for selective removal and transformation of phenolic contaminants

Complete degradation of organic pollutants in water often demands substantial energy and chemical inputs. In this study, we introduce a novel nanomotor-assisted ultrafiltration (UF) system for highly selective and efficient removal of micropollutants. These nanomotors, engineered by encapsulating catalase (CAT) and horseradish peroxidase (HRP) enzymes within ZIF-8 metal-organic frameworks, exhibit self-propulsion and catalytic oxidation capabilities. In treating phenolic pollutant-contaminated water, ZIF-8 acts as a protective and selective gate that shields enzymes from background interference and enriches hydrophobic phenolic compounds (XLogP > 2), enabling up to 99.5% removal efficiency by selective oxidation of targeted species. Notably, HRP-mediated oxidation generates phenoxy radicals, which couple and polymerize into hydrophobic oligomers that bind to the ZIF-8 surface and are effectively separated via low-pressure UF. This system minimizes energy input while leveraging enzymatic polymerization as a natural pathway for pollutant transformation, paving the way for advanced oxidation-filtration technologies as a sustainable solution for water treatment.