Enhancing lithium ion capture by using a negatively overcharged biomass-based hybrid adsorbent

Abstract

A new negatively overcharged biomass-based hybrid adsorbent, obtained by treatment of Pichia stipitis cells with activated carbon in the presence of Fe3+ ions, was investigated for the capture of Li+ ions from aqueous solutions. Production optimization studies revealed complete interaction between the components of the hybrid adsorbent; the highest adsorption capacity was attained when 2 g/L dry yeast cells were treated with 0.3 g/L activated carbon and 0.072 g/L Fe3+ at pH 9. Effects of treatment were evaluated by surface properties characterization. Treatment yielded a synergistic effect, enhancing Li+ adsorption capacity by increasing surface negativity. Adsorption studies demonstrated that Li+ ions were adsorbed rapidly by physical interaction and released into the media at varying rates and amounts based on the sorbent’s surface properties. Effects of adsorption parameters on Li+ adsorption and desorption trajectories were investigated systematically; maximum adsorption capacity attained was 245.3 μmol Li/g hybrid adsorbent at pH 10.0 and an initial Li+ concentration of 50 mg/L. Langmuir isotherm model fit the experimental data better than Freundlich model. Adsorbed Li+ ions were completely recovered in acidic media at each instance of repeated utilization of the hybrid adsorbent and dry cells; hybrid adsorbent demonstrated greater stability in performance during repeated use.