Mechanisms of hydroxyl radical production from abiotic oxidation of pyrite under acidic conditions

The OH produced had a significant impact on the transformation of contaminants in the environment. Anoxic pyrite suspensions oxidized 13.9% As(III) (C0 = 6.67 μM) and 17.6% sulfanilamide (C0 = 2.91 μM) within 10 h at pH 2.6 and 10 g/L pyrite, while oxic pyrite suspensions improved the oxidation percentages to 55.4% for As(III) and 51.9% for sulfanilamide. The ratios of anoxic to oxic oxidation are consistent with the relative contribution of surface sulfur-defects to OH production. However, Fe2+ produced from pyrite oxidation competed with the contaminants for OH, which is of particular significance with the increase of time in a static environment. We conclude that OH can be produced from abiotic oxidation of pyrite under acidic conditions, and the production dramatically increases in the the presence of O2. The oxidation induced by the OH produced should be taken into account for substance transformation due to its highly reactive nature.