Improve the durability of lithium adsorbent Li/Al-LDHs by Fe3+ substitution and nanocomposite of FeOOH

The selective extraction of lithium from brine by lithium aluminum layered double hydroxides (Li/Al-LDHs) adsorption is used industrially. To maintain the structural and performance stability of the Li/Al-LDHs adsorbent, the Li/Al-LDHs adsorbent can be doped with some high electron density metals such as Fe(III) and regenerated by dilute Li-containing aqueous solution. In this study, we use Fe(III) doping and FeOOH nanocomposite to stabilize the structure of Li/Al-LDHs. The nanocomposites of Li/Al-LDHs, Fe dopped Li/Al-LDHs (Fe-Li/Al-LDHs), and FeOOH were synthesized by the phase-separated sol–gel method and granulated by using crosslinked alginate polymers. The nanocomposites and granulated nanocomposites were characterized by SEM, TEM, XPS, FT-IR, and XRD analyses. The adsorption–desorption performance of the granulated nanocomposites was evaluated with a single LiCl solution and the brine from Da Qaidam Salt Lake. The isotherms, kinetics, and thermodynamics parameters and Arrhenius parameters of the lithium adsorption of the granulated nanocomposites were obtained. At the 80% mass loading of the nanocomposites in the granulation, the granulated nanocomposites statically adsorbed 9.46 mg/g lithium and dynamically 8.18 mg/g lithium from Da Qaidam Salt Lake brine. The Fe(III) doping and nanocomposite with FeOOH reduced the dissolution of the Li/Al-LDHs in the granulated nanocomposites and did not negatively affect the adsorption capacity of the granulated nanocomposites.