Recently, activation of peroxymonocarbonate (HCO4–), formed upon H2O2–HCO3– interaction, by heat and/or catalyst has been reported to generate a suite of reactive species such as HO•, CO3•–, and 1O2. Here, we systematically examine the uncatalyzed thermal activation of HCO4– across environmentally relevant pHs (8.3–10.3) and carbonate concentrations (0–10 mM) by measuring the degradation of a range of organic contaminants with differing reactivity toward HCO4–, HO•, CO3•–, and 1O2. Our results show that, in the temperature range 20–60 °C, thermal activation of HCO4– is negligible, with contaminant removal instead driven by trace Cu impurities that catalyze H2O2 decomposition. Furthermore, Cu-mediated activation of HCO4– is insignificant, indicating that the previously reported “HCO4– activation” likely reflects secondary H2O2 activation. Overall, these findings highlight the need for rigorous control of trace-metal impurities upon evaluation of uncatalyzed thermal activation of various oxidants/reductants. Furthermore, future studies on the catalytic activation of HCO4– must provide direct, unambiguous evidence of the role of HCO4– because carbonate-dependent effects on the oxidative performance do not necessarily indicate that HCO4– is involved.
Perumpully et al. (Thu,) studied this question.