Corrosion of iron powder (ZVI) under abiotic and biotic conditions of groundwater with nitrate and sulfate contamination

The paper presents the results of laboratory model experiments on the corrosion of metallic iron powder (ZVI) in groundwater samples from an aquifer near an Electrochemical Plant (ECP) (Zelenogorsk, Krasnoyarsk Krai, Russia) with nitrate, sulfate, and uranium contamination. Particular attention is paid to the role of microorganisms in the process of iron corrosion and the formation of corrosion products. ZVI corrosion is significantly accelerated in the presence of nitrate ions under biotic and abiotic conditions. Under abiotic conditions the main corrosion products are iron oxides such as ferrihydrite and magnetite. It has been established that microbial processes in the presence of sulfate ions accelerate the corrosion process and lead to the formation of predominantly sulfide-ferrous mineral phases. Thus, in technogenic underground waters, the process of ZVI corrosion has a complex mechanism, in which both microbial factors (formation of hydrogen sulfide, organic microbial metabolites containing organic acids, carbonate ions) and geochemical factors participate. In this case, the role of microbial factors prevails. Biogenic products of metallic iron corrosion absorb uranium an order of magnitude better than products obtained under abiogenic conditions.