Manganese is the second most prevalent transition metal in Earth’s crust after iron and plays an important role in the biogeochemical cycling of carbon, nitrogen, phosphorus, sulfur, and iron in sediments. The transformation of Mn(III,IV) (oxyhydr)oxides in subsurface environments also influences the transport and fate of a variety of organic and inorganic contaminants. As Mn(III,IV) (oxyhydr)oxides constitute the strongest natural oxidant besides dissolved oxygen in the environment, their reaction kinetics is too fast to be followed by conventional analytical techniques. As a result, the mechanism of oxidation of a number of environmentally relevant compounds by Mn(III,IV) (oxyhydr)oxides is difficult to characterize. In this study, voltammetric techniques were developed to follow the kinetics of thiol and arsenite oxidation by Mn(III,IV) (oxyhydr)oxides and investigate the mechanism of these two reactions in environmentally relevant conditions. Coupling bulk measurements with the speciation capabilities of voltammetric techniques allows to gain new insights into the mechanism and potential importance of these reactions in natural environments.

Insights into the mechanism of reduction of manganese oxides by thiols and arsenite

ACS Spring Meeting 2021

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