Phosphate-based HTi2(PO4)3 was a novel lithium ion with a NASICON network structure. In this work, Cr doped was used to improve the adsorption performance by expanding the Li+ transport channel and increasing the hydrophilicity of the adsorbent. The crystal structure of Cr-LTPO-0.5 was characterized by XRD, XPS, Contact angle and FT-IR analysis, and the morphology of Cr-LTPO-0.5 was analyzed by SEM and HR-TEM.
Cr-HTPO-0.5 was obtained after acid washing of Cr-LTPO-0.5. The adsorption of Li+ on Cr-HTPO-0.5 was consistent with the Langmuir isothermal model and pseudo-2nd-order kinetic model, in which the adsorption was endothermic and spontaneous process.
The structure and adsorption energy of Li+ on Cr-HTPO-0.5 were calculated by the density function theory (DFT) to assess the feasibility of lithium uptake. Cr-HTPO-0.5 showed remarkable selectivity for Li+ on heteroatoms in artificial brines.
These results made Cr-HTPO-0.5 as a highly promising candidate for applications in Li+ recovery.