Effect of Acid Treatment on a λ-MnO2 Granulated Adsorbent for Adsorptive Recovery of Lithium

Abstract

Lithium is essential for the production of lithium-ion batteries, and the demand is expected to further increase. λ-MnO2 adsorbent exhibits superior selectivity of Li(I) adsorption against other alkali and alkali earth ions. In this study, the Li(I) adsorption on λ-MnO2 adsorbent granulated with alumina binder in batch and column operations, in particular, effect of acid treatment on the adsorbent was investigated. From the analysis of the adsorption isotherm by Langmuir’s model, and the maximum adsorption was calculated to be 1.64 mmol/g. The granulated adsorbent before and after excessive acid treatment was analyzed by XPS. Based on the change at the narrow spectrum attributed to the 2p orbital, decrease of Mn(II) due to the dissolution of adsorption body was suggested. The adsorption and desorption kinetics of Li(I) on the sieved granulated adsorbents were compared. The kinetics of both adsorption and desorption were explained by intraparticle diffusion equations, and the adsorbent with smaller particle size showed faster adsorption. As the rate of disproportionation reaction for the adsorbent resulting in the elution of small amount of manganese is competitive with desorption rate of Li(I) based on ion exchange, kinetic control of manganese elution in the desorption process seems to be difficult. These results should be informative for the operation of Li(I) recovery using the granulated λ-MnO2 adsorbent.