Adsorption weakening mechanism and regulation strategy of aluminum-based lithium adsorbents in carbonate-style brines

An efficient adsorption-strengthening regulation was developed for aluminum-based lithium adsorbents (Li/Al-LDHs) in carbonate-type salt lakes based on reasons for adsorption performance degradation. It was confirmed by adsorption-desorption experiments and density functional theory (DFT) that CO32- in brines preferentially entered Li/Al-LDH interlayers with a tighter binding energy to the laminates, resulting in the decreasing sharply cyclic re-adsorption capacity. Intercalated CO32- was effectively removed by high concentration of Cl- to enhance Li+ re-adsorption, and X-ray absorption spectroscopy (XAS) demonstrated that this process had no impact on the host laminate integrity. On this basis, an innovative strategy of incorporating interlayer anion regulation into lithium extraction process was proposed and employed for the continuous extraction of Li+ from carbonate-type brines, bringing about a completely restored re-adsorption capacity with cyclic stability, and the lithium extraction capacity per unit time could be exceeded by about double compared with the conventional process, assuring the efficiency of lithium extraction from carbonate-type brines by Li/Al-LDHs.