Photocatalytic degradation of metronidazole and bacteria disinfection activity of Ag-doped Ni0.5Zn0.5Fe2O4

The health of human beings is threatened by drug-resistant diseases due to excessive antibiotic use. A promising cost-competitive water disinfection technology is photocatalytic disinfection. In this study, Ag-doped Ni0.5Zn0.5Fe2O4 photosensitive catalyst (Ag-d-NZF) was synthesized for disinfection of metronidazole antibiotic and bacteria-contaminated water. Ag-d-NZF was characterized and results revealed it has a bandgap of 2.96 eV, exhibiting a stable photocurrent response of 1.36 mu A cm-2 with a crystallite size of 15.3 nm and crystallinity of 74.5 %. After 360 min of UV-assisted irradiation under optimal conditions (pH 3 and 7 mM H2O2), 10 mg Ag-dNZF degraded 99.9 % of 50 mgL-1 MZ with an apparent rate constant of 0.0103 min- 1. Ag-d-NZF maintained 75.2-80.9 % efficiency in the presence of interfering ions and tylosin antibiotic. After 65 min, 25 mg of Ag-d-NZF demonstrated bactericidal effects (100 % inactivation) in the dark and under UV light against E. coli and S. aureus, respectively. The electrical energy consumed per order revealed that UV/ Ag-d-NZF/H2O2 required 26.84 kW h to degrade MZ which is equivalent to $1.34 per m3 of MZ. A plausible photocatalytic degradation mechanism was established, in which center dot O2- was the dominant radical while center dot OH radicals and h+ contributed moderately to the decomposition processes.

Automated summary

The synthesis of Ag-doped catalyst can effectively disinfect water containing metronidazole antibiotics and bacteria, with high efficiency and stability. Furthermore, the method can kill E. coli and S. aureus under both light and dark conditions.