Reaction kinetics of molybdenum dissolution by hydrogen peroxide in acidic and alkaline solutions using tartaric acid and sodium hydroxide: A semi-empirical model with rotating disc method

Abstract

Molybdenum is an amphoteric metal that dissolves in both acidic and alkaline solutions. This fundamental study explores a sustainable process for the dissolution of molybdenum, focusing on the reaction kinetics in H₂O₂, H₂O₂-NaOH, and H₂O₂-C₄H₆O₆ solutions. A rotating disc method was applied with the Levich's equation. Semi-empirical models with activation energy were developed for the H₂O₂-NaOH and H₂O₂-C₄H₆O₆ solutions. The study examined the effects of rotating speed, disc surface area, temperature, H₂O₂, NaOH, and C₄H₆O₆ concentrations, along with rotating speed, disc surface area, and temperature. Hydrogen peroxide significantly impacted molybdenum dissolution rates across all three solutions. The reaction order of hydrogen peroxide concentration in the H₂O₂ solution was greater than that of the H₂O₂-NaOH and H₂O₂-C₄H₆O₆ solutions. The complex of molybdenum peroxo was formed in H₂O₂ and H₂O₂-NaOH solutions but decomposed at a temperature ≥50°C. The activation energies were determined to be 49.90, 43.60, and 41.10 kJ/mol for the H₂O₂, H₂O₂-NaOH, and H₂O₂-C₄H₆O₆ solutions.