Lithium recovery from Mexican geothermal brine via microwave-synthesized ion sieves

This paper investigates for the first time the feasibility of lithium recovery using lithium ion-sieves from a Mexican geothermal brine from a well of Cerro Prieto power plant. The materials were prepared following the microwave-assisted hydrothermal route to favor their sustainability. Also, the effect of the three manganese-based compounds as precursors was evaluated in which the vacancies were generated by acid treatment, by varying the acid concentration and the contact time. The structural characterizations showed that manganese sulfate was an efficient precursor for synthesizing LiMn 2 O 4 spinel. The results of the uptake experiments, varying the pH of the Li solution showed that the highest sorption capacity is obtained at pH 12. The adsorption kinetics was better described by a pseudo second order equation (R 2 =0.9392). According to the Weber-Morris model, the process seems to be governed by film diffusion rather by intraparticle diffusion. The maximum adsorption capacity that was achieved was 9.64 mg/g and the thermodynamic equilibrium was best described by the Freundlich isotherm (R 2 =0.9769). Finally, the material was able to retain a competitive uptake capacity after five adsorption-desorption cycles.