Adsorption of lithium ions from liquid resources by dual surfactant rod mesoporous composite lithium-ion sieve PVB-HTO-1

Spinel-type titanium-based lithium-ion sieve H₄Ti₅O₁₂ has excellent theoretical adsorption capacity and selectivity. Still, spinel-type lithium adsorbents prepared in existing studies have poor adsorption, poor recyclability, and difficulty in recovery. To solve the above problems, composite mesoporous ion sieves, Polyvinyl Butyral-H₄Ti₅O₁₂–1 (PVB-HTO-1) modified with dual surfactants, were synthesized for the first time in this paper. Hydrophilic lithium-ion sieve HTO-1 with a mesoporous structure was synthesized by adding two surfactants, CTAB and F127. Then the modified ion sieve was composited with PVB to make a fine rod-like composite material, PVB-HTO-1, with a diameter of no more than 0.5 mm, to solve the limitation of the industrial application that the recycling of powdered ion sieve is difficult. The bi-component surfactant-derived ion sieve, PVB-HTO-1, exhibits superior hydrophilicity and possesses a porous mesoporous framework that facilitates ion exchange processes, achieving adsorption equilibrium within a timeframe of three hours. It demonstrates a remarkable maximum adsorption capacity of 53.25 mg/g. Even after undergoing five cycles of adsorption and desorption, the material's adsorption capacity remains at over 90 % of its initial value, indicative of its robust cyclic stability. The uptake of Li⁺ ions by PVB-HTO-1 aligns with the pseudo-second-order kinetic model and conforms to the Langmuir isothermal adsorption model.