Improving ferrate disinfection and decontamination performance at neutral pH by activating peroxymonosulfate under solar light

Abstract

In this work, the effect of solar light as a 'reducing agent' in Fe(VI)/PMS process for disinfection and decontamination of water was investigated. Single, double and triple-factor disinfection processes were systematically studied against Escherichia coli and validated on sulfamethoxazole. The experiments performed with PMS or Fe(VI) in dark conditions only achieved 1-log reduction in 2 h, while no significant enhancement was found in the Fe(VI)/PMS system. The introduction of solar light in either PMS or Fe(VI) process enhanced the E. coli inactivation since complete inactivation (6-log) was reached at 90 min. However, the best improvement was done with the triple-factor disinfection process (Fe(VI)/PMS/solar light) which presented 6-log reduction at only 40 min. In the case of sulfamethoxazole, more than 70% removal was achieved under the Fe(VI)/PMS/solar light system, while only about 20% was observed with single and double-factor processes. Our study revealed the light spectrum distribution effects, the iron implications, while a main role for 〖HO〗^¿ and the participation of 〖SO〗_4^(¿-) was found, without overlooking the direct effects of solar light and PMS itself, as well as the possible involvement of other transient species. Overall, the efficacy of the Fe(VI)/PMS/solar light process against a series of microorganisms combined with the effectiveness at near-neutral pH, suggest its suitability for further assessment in disinfection and/or decontamination of water.