Nano silver oxide-modified activated carbon as a novel catalyst for efficient removal of bacteria and micropollutants in aquatic environment

Abstract

Heterogeneous Fenton process is a promising water treatment technology for sterilization and degradation of organic pollutants, due to the strong oxidation of hydroxyl radicals (OH˙) generated. However, the low H₂O₂ activation efficiency and the instability of catalyst leading to low OH˙ production restricted development of this technology. Herein, we synthesized a novel porous activated carbon-loaded nano silver oxide (nAg₂O/AC) catalyst to enhance the activation of H₂O₂ for removing bacteria (E. coli) and micropollutants (Tetracycline, TC) from water. In the nAg₂O/AC Fenton system, reductive hydroxyl groups on AC accelerated Ag(I)/Ag cycle through mediated electron transfer, which markedly increased H₂O₂ activation efficiency to 73.7% (About 2.9 times that of traditional Fenton). Hence, nAg₂O/AC Fenton achieved up to 6.0 log and 100% removal efficiency for E. coli and TC, respectively. The OH˙ as the major oxidizing species in nAg₂O/AC Fenton system was detected and verified by radical scavenging tests and electron spin resonance (ESR) measurement. After 4 and 5 cycles of experiments, the removal of E. coli and TC still reached 5.2 log and 96%, respectively, confirming good stability of nAg₂O/AC for considerable application prospects. This study concluded that nAg₂O/AC is a promising H₂O₂ catalyst for simultaneous removal of bacteria and micropollutants in aqueous environment.