Impact of aqueous environments on hydrogen peroxide activation by manganese oxides: Kinetics and the critical role of bicarbonate

MnO2 activating H2O2 is a promising way in the field of advanced oxidation processes (AOPs) and in situ chemical oxidation (ISCO) to remove contaminants. However, few studies have focused on the influence of various environmental conditions on the performance of MnO2-H2O2 process, which restricts the application in real world. In this study, the effect of essential environmental factors (ionic strength, pH, specific anions and cations, dissolved organic matter (DOM), SiO2) on the decomposition of H2O2 by MnO2 (epsilon-MnO2 and beta-MnO2) were investigated. The results suggested that H2O2 degradation was negatively correlated with ionic strength and strongly inhibited under low pH conditions and with phosphate existence. DOM had a slight inhibitory effect while Br-, Ca2+, Mn2+ and SiO2 placed negligible impact on this process. Interestingly, HCO3- inhibited the reaction at low concentrations but promoted H2O2 decomposition at high concentrations, possibly due to the formation of peroxymonocarbonate. This study may provide a more comprehensive reference for potential application of H2O2 activation by MnO2 in different water systems.

Automated summary

In this study, the influence of various environmental conditions on the performance of MnO2-H2O2 process was investigated. The results showed that the degradation of H2O2 was affected by ionic strength, pH, specific anions and cations, dissolved organic matter (DOM), and SiO2. The presence of low pH and phosphate inhibited the reaction, while DOM had a slight inhibitory effect. The study also found that HCO3- inhibited the reaction at low concentrations but promoted H2O2 decomposition at high concentrations.