The post-Li2CO3 precipitation liquor (the residual raffinate after Li2CO3 precipitation with pH of 10-12), referred to as the mother liquor, still contains 20-25 % of unrecovered Li+.Efficiently extracting lithium ions from the mother liquor has become one of the key challenges to enterprises.A titanium-based ion sieve precursor (LTO-Co/CTAB) was prepared via simultaneous doping of cobalt (II) acetate tetrahydrate ((CH3COO)2Co·4H2O) and cetyltrimethylammonium bromide (CTAB) by solid-phase synthesis method.After acid washing of LTO-Co/CTAB, the Co/CTAB co-doped titanium-based ion sieve (HTO-Co/CTAB) was characterized by XRD, SEM, XPS, etc.Adsorption isotherms and kinetics of Li+ on HTO-Co/CTAB, along with its Li+/Na+ and Li+/K+ separation selectivity in the mother liquor were investigated.The results showed that the solid-phase Co doping coupled with CTAB-assisted dispersion enabled successful nano-scale refinement and functional modification of HTO-Co/CTAB.The formation of Co-O-Ti bonds, lattice distortions and its short diffusion paths of nanoparticles (100-200 nm) were all beneficial for the diffusion and enrichment of Li+ within the channels of HTO-Co/CTAB.The adsorption behavior of Li+ on HTO-Co/CTAB was well-described by Langmuir isotherm adsorption model (R2 = 0.996) and pseudo-second-order kinetic model (R2 = 0.996).An equilibrium uptake capacity of HTO-Co/CTAB for Li+ in the mother liquor (initial concentration of Li+, Na+ and K+ was 1450, 33,800 and 6900 mg/L) could reach 39.78 mg/g, which was 39 % higher than that of HTO, and the equilibrium time was shortened to 5 h compared to HTO (20 h).The separation factors of Li+/Na+ and Li+/K+ for HTO-Co/CTAB were 677.45 and 284.43, resp., and it had excellent stability.