Influence of V, Mn, As, and Sb on Cr Behavior in Alkaline Environment

Abstract

This study addresses the behavior of hexavalent chromium (Cr(VI)) in contaminated soils and the challenges of remediation, with a specific focus on the impact of trace elements coexisting with chromium. Cr(VI), a toxic and highly mobile form, is commonly reduced to the less toxic trivalent chromium (Cr(III)) through various remediation methods such as treatment with Fe(II). However, Cr(VI) has been observed to reappear in treated soils over time, posing ongoing environmental risks. This research examines the role of 31 trace elements in influencing Cr(VI) reduction and potential reoxidation of Cr(III). The study identified four elements—V(IV), Mn(II), As(III) and Sb(III)—that may significantly alter Cr behavior due to their varied oxidation states. Through experiments, the results showed that Mn(II) and V(IV) contribute to Cr(III) reoxidation, a process that can revert Cr to its more toxic form, Cr(VI). Additionally, As(III) was found to potentially enhance Cr(III) dissolution, suggesting a pathway by which Cr(III) could return to a soluble, reactive state in alkaline conditions. This study suggests that coexisting trace elements, often neglected in traditional remediation approaches, may play a crucial role in the stability of Cr(VI) remediation. Addressing these interactions can inform more robust and effective strategies for managing Cr contamination in environmental settings, particularly where industrial waste has led to diverse element contamination. The findings emphasize the importance of considering trace element effects to prevent Cr(VI) re-emergence and improve the remediation technologies.