Sorption of molybdenum from sulfuric acid solutions on Purolite A-100 anionite: Equilibrium and isotherm modeling

Abstract

The growing demand for molybdenum and the involvement of low-grade and man-made raw materials in the processing necessitate the development of effective hydrometallurgical methods for its extraction from complex solutions. In this work, the sorption behavior of molybdenum from sulfuric acid solutions was studied using a weakly basic anionite Purolite A-100. Sorption experiments were performed under static conditions at a temperature of 25 ^оC with a variation in the initial concentration of molybdenum, and the equilibrium data were analyzed using Langmuir, Freundlich, and Dubinin–Radushkevich models to evaluate the nature of the interaction and describe the sorption process. It is shown that the equilibrium is most adequately described by the Langmuir model (R² = 0.9868), which indicates the predominantly monolayer nature of sorption. The calculated value of the average sorption energy (E ≈ 6.28 kJ/mol) indicates that the sorption process occurs predominantly through weak physicochemical interactions with a contribution of ion-exchange mechanisms. With an increase in the concentration of molybdenum, a decrease in the degree of extraction is observed, associated with saturation of the active centers of the sorbent, while the formation of sulfate forms of molybdenum and competition of sulfate ions in a sulfuric acid medium have a significant effect. The results obtained characterize the equilibrium behavior of molybdenum in sulfuric acid solutions and can be used in the development and optimization of ion exchange technologies for its extraction from acidic media.