Abstract: Influencing factors in the catalytically bactericidal process over a Ag-Ce/AlPO4 catalyst against E.coli in water were investigated. The bactericidal effect of the catalyst decreased with the increase in initial bacterial concentration. A 100% inactivation of E.coli using Ag-Ce/AlPO4 at 25 ℃ was achieved in 120 min when the initial bacterial concentration was 5×105 CFU/ml. Therefore, this catalytic method is sufficient for disinfection of drinking water. Once the initial bacterial concentration was fixed, the bactericidal activity increased with increasing temperature from 25 to 40 ℃. The pH value also played an important role in the bactericidal process. The Ag-Ce/AlPO4 catalyst exhibited high bactericidal activity under weak alkaline conditions, while almost no bactericidal effect was observed at acidic pH. Electron spin resonance was used to detect the reactive oxygen species involved in the bactericidal process at different pH values. Hydroxyl radical·OHwith strong oxidative ability proved to be formed under weak alkaline conditions and was not observed at acidic pH. These results give evidence of our proposed catalytically bactericidal mechanism, in which·OHis the key intermediate responsible for the efficient inactivation of E.coli by Ag-Ce/AlPO4 in water at room temperature.

Key words: aluminum phosphate, silver, cerium, supported catalyst, reactive oxygen species, catalytically bactericidal process, E.coli, drinking water