To unsnarl the mechanism of disinfection of Escherichia coli via visible light assisted heterogeneous photo-Fenton reaction in presence of biochar supported maghemite nanoparticles

Abstract

Waterborne diseases caused by bacterial contamination of water sources remain one of the perilous public health challenges in low and middle-income countries. In this regards, we report a photo-Fenton like reaction for disinfection of water contaminated with common waterborne bacterium, Escherichia coli under visible light using biochar supported maghemite nanoparticles (M/biochar). Waste leaves of Cymbopogon flexuosus impregnated with ferric chloride were subjected to pyrolysis, which leads to the formation of M/biochar. M/biochar was found to be more effective than only Maghemite nanoparticles for disinfection of targeted bacterium in a photo-Fenton like process. Fluorescence and scanning electron microscopy images indicated compromization of bacterial cell membrane. Experimental evidence infers that hydroxyl radicals could be the major component responsible for disinfecting E. coli in the present process. Results obtained from Resazurin assay indicate that reactive oxygen species produced during photo-Fenton like reaction may have impeded the oxido-reductase protein system of the bacteria and hence hampered its metabolic activity. Proposed process has been successfully investigated for disinfection of real water samples contaminated with E. coli and treated water did not induce a noticeable toxic effect on the growth of maize plants and hence could have the potential for real world applications.