Influence of hydronium, sulfate, chloride and other non-carbonate ions on hydrogen generation by anaerobic corrosion of granular cast iron

Abstract

Permeable reactive barriers are successfully applied for the removal of various contaminants. The concomitant reduction of hydrogen ions and the subsequent formation of hydrogen gas by anaerobic corrosion lead to decreased pore volume filled with water and thus residence times, so called gas clogging. Long term column experiments were conducted to elucidate the impact of ubiquitous water constituents on the formation of hydrogen gas and potential passivation due to corrosion products. The collected gas volumes revealed a relation to the hydronium concentration (pH) but were only slightly increased in the presence of chloride and sulfate and not significantly influenced in the presence of phosphate, silicate, humic acid and ammonium compared to deionized water. Significant gas volumes within the reactive filling were verified by gravimetry. The presence of nitrate completely eliminated hydrogen formation by competition for electrons. Solid phase analyses revealed that neither chloride nor sulfate was incorporated in corrosion products in concentrations above 0.1 weight percent, and they did not alter the formation of mainly magnetite in comparison to deionized water.

Keywords: Anaerobic corrosion; Corrosion products; Gas generation; Hydrogen; Passivation; Permeable reactive barrier.