Removing antibiotic resistance genes through the synergistic effect of hydroxyl radical and hypochlorite radical generated in a CeO2@CNT electrified membrane – NaClO system

Abstract

The removal of antibiotic resistance genes (ARGs) is important for inhibiting the spread of antibiotic resistance in the aquatic environment. In this study, a series of coupled advanced oxidation-disinfection systems were developed based on a carbon nanotube membrane modified with different CeO2 nanocrystals and NaClO (denoted as CeO2@CNT-NaClO system). The removal performance of ARGs by the CeO2@CNT-NaClO systems was tested by treating the simulated water samples containing Pseudomonas sp. HLS-6 with sul1 genes and Escherichia coli TOP10F with tetA genes. The results showed that the CeO2@CNT-NaClO system showed the superior disinfection efficiencies compared to using sole CeO2@CNT electrified membrane and sole NaClO. After treatment by the CeO2@CNT-NaClO system, Pseudomonas sp. HLS-6 and Escherichia coli TOP10F were completely inactivated, and the absolute abundances of sul1 and tetA genes decreased by 4.8 log and 1.8 log, respectively. The probe compounds and quenching experiments showed the synergistic effect of •OH and •ClO is the main contributor to the high removal efficiencies of ARGs by the CeO2@CNT-NaClO system. The rectangular CeO2 particles with (200) and (111) crystal facets exhibited the largest amounts of oxygen vacancy and Lewis acid sites, which favored the coupled system to generate the highest cumulative concentration of •OH and •ClO. This led to a synchronous high-efficiency removal of ARGs and antibiotics in the CeO2@CNT-NaClO system.