China Nonferrous Metallurgy

In response to the challenges posed by low lithium adsorption capacity, slow adsorption rates, and poor stability of titanium-based lithium ion sieves in practical applications, this study synthesizes a lithium ion sieve utilizing lithium carbonate, titanium dioxide, and lithium acetate as raw materials through an improved high-temperature solid-state method. The synthesized precursor of the lithium ion sieve was characterized with respect to its morphological appearance and crystalline phase composition. Performance tests were conducted using brine sourced from a domestic salt lake as the raw material, focusing on selectivity for impurity ions, cyclic adsorption performance, and the mechanisms underlying titanium leaching. The following key conclusions were drawn: The optimal preparation conditions for the precursor of the lithium ion sieve include a calcination temperature of 699℃, a n_TiO2/n（_Li2O+TiO2） ratio of 0.45, a calcination time of 24h, and an n_CH3COOLi/n（_{Li2CO3+CH3COOLi}） ratio of 0.2:1. Under these conditions, the maximum saturated adsorption capacity for brine reached 27.42mg/g; after multiple cycles of adsorption-desorption tests, the working adsorption capacity was determined to be 8mg/g (in comparison to approximately 6mg/g for commercially available adsorbents with a 30-minute adsorption period), with an Li+ desorption rate around 85%. The selectivity towards impurity ions is relatively favorable with ratios such as Li/Na=4.5, Li/K=25, Li/Mg=13, and Li/Ca=40; thus indicating that separation coefficients rank as α_Li/K＞α_Li/Mg＞α_Li/Na＞α_Li/Ca. Furthermore，the leaching of titanium from the lithium ion sieve is attributed to structural dissolution associated with lithia-titanate formation.