Mechanistic elucidation and sustainable application of tartaric acid-mediated pentavalent vanadium reduction

This study investigated the effectiveness of tartaric acid (TA) for the direct reduction of pentavalent vanadium (V(V)), a critical process in vanadium-related industries. Leveraging TA's carboxyl groups, which showed promise as reducing agents for V(V), the research systematically evaluated the effects of key parameters including reaction temperature, reaction time, H 2 SO 4 concentration, and TA dosage on reduction efficiency. Response surface methodology (RSM) analyzed parameter significance and interactions, while density functional theory (DFT) elucidated the molecular reduction mechanism. The process was further validated using an industrially sourced vanadium-rich solution. Results demonstrated that TA effectively reduces V(V) under elevated temperatures and TA dosage, achieving 100% within a short time under optimized conditions. RSM revealed all parameters positively influenced the reduction process, ranked by significance as: reaction temperature > reaction time > H 2 SO 4 concentration > TA dosage, underscoring the dominance of thermal activation. DFT analysis identified the molecular mechanism: the carbon atom within TA's carboxyl group (-COOH) donated lone pair electrons to V(V), facilitating reduction to V(IV). Successful application to the industrial vanadium solution confirmed TA's effectiveness. This study established TA as an efficient V(V) reducing agent, clarified its electron-transfer mechanism, and confirmed its dual role as both reductant and complexing agent.