Recovery of Li from seawater using Li1.33Mn1.67O4 immobilized multi-stage column system

Abstract

The securing of lithium (Li) from resources containing low concentrations of Li+, such as brines and seawater, is receiving a lot of attention due to the rapid increase in demand for lithium-ion batteries. In this respect, the adsorption process is regarded as the most appropriate method for the direct extraction of Li+ from low-concentration solutions. However, for practical application, the adsorbent materials need to be shaped into granules, spheres, or foams using binding materials, which can reduce the adsorption performance by blocking adsorption sites. To overcome this drawback, an alternative method is proposed herein whereby the adsorbent lithium manganese oxide (LMO) powder is loaded into a multi-stage column (MSC) system equipped with a fabric filter. The optimum conditions for the fabrication of the LMO powder are found to be an Li/Mn molar ratio of 0.8 with a heating temperature of 500 °C for 4 h, and its delithiated product giving a maximum adsorption capacity of 23.9 mg g−1 from Li-spiked seawater (2–60 ppm). By comparison, stirring the adsorbent powder in solution for the same adsorption time yielded 22.8 mg g−1. The MSC adsorption process fits well with the Langmuir isotherm and pseudo second-order kinetics. To confirm the feasibility of the proposed method, its performance is also evaluated in the extraction of Li+ from natural seawater, giving Li+ recoveries ranging from 4 to 4.9 mg g−1 during repeated adsorption/desorption runs. Thus, the proposed method provides a practical Li+ extraction approach that can recover Li+ with a good adsorption performance.