Adsorption performance and mechanism of Li(+) from brines using lithium/aluminum layered double hydroxides-SiO(2) bauxite composite adsorbents

A combined method of solid-phase alkali activation and surface precipitation was used to prepare the lithium/aluminum layered double hydroxides-SiO(2) loaded bauxite (LDH-Si-BX) and applied to adsorb Li(+) in brines. In the study, various characterization techniques such as SEM, XRD, BET, Zeta potential, and x-ray photoelectron spectroscopy (XPS) were applied to characterize and analyze the adsorbents. The adsorption-desorption performance of LDH-Si-BX for Li(+) in brines was systematically investigated, including adsorption temperature, adsorption time, Li(+) concentration, and regeneration properties. The results indicated that the adsorption kinetics were better fitted by the pseudo-second-order model, whereas the Langmuir model could match the adsorption isotherm data and the maximum Li(+) capacity of 1.70 mg/g at 298K. In addition, in the presence of coexisting ions (Na(+), K(+), Ca(2+), and Mg(2+)), LDH-Si-BX showed good selective adsorption of Li(+), and the pH studies demonstrated that the adsorbents had better Li(+) adsorption capacity in neutral environments. In the adsorption process of real brines, LDH-Si-BX had a relatively stable adsorption capacity, and after 10 cycles of adsorption and regeneration, the adsorption capacity decreased by 16.8%. It could be seen that the LDH-Si-BX adsorbents prepared in this report have the potential for Li(+) adsorption in brines.