Synthesis Of H₂TiO₃ And Its Application In Lithium Extraction From Liquid Lithium Resources

With the increasing grim problems of global energy crisis and environmental pollution,the development and utilization of new energy strategic metals is growing important.Among these metals,lithium as an important energy metal that can be widely utilized in batteries,alloys,ceramics,and other fields.And the demand of lithium also has continued to rise with the rapid development of new energy technology and electric vehicles.However,lithium extraction from lithium ore is not enough to meet the market demand of future,and liquid lithium resources with vast reserves may prove to be a crucial lithium source.The adsorption method for lithium recovery from liquid lithium resources offers several advantages,including simple process and low energy consumption et.al.In addition,the selection of an appropriate adsorbent is a critical factor for successful technology application.Layered metatitanic acid（H₂TiO₃）with exceptional cyclic stability and relatively high theoretical adsorption capacity is a promising lithium ion sieve（LIS）adsorbent with great potential for research and practical application in the future.Nonetheless,H₂TiO₃still remains some issues such as limited adsorption capacity,slow adsorption rate,and difficult powder recovery.In order to improve the adsorption performance and recovery of LISs,a series of H₂TiO₃was designed and synthesized which investigated the feasibility of lithium extraction from liquid lithium resources.The specific research contents and conclusions are presented in detail below.1.H₂TiO₃ with high specific surface area were prepared by using ammonium bicarbonate as porogen to adjust the morphology and pore structure of materials.The physicochemical properties of the materials were analyzed through various characterization methods,and adsorption performance of LISs was studied via adsorption experiments,then determined that 5 wt%NH₄HCO₃was the optimal dosage for synthesis.Equilibrium adsorption capacity of HTO-5 synthesized was37.96 mg·g^-1,which was 37.9%higher than that of HTO-0 prepared without adding porogen.The introduction of NH₄HCO₃resulted in HTO-5 demonstrating a high specific surface area,which facilitated the exposure of a large number of active adsorption sites and improved the Li⁺adsorption capacity.Moreover,HTO-5exhibited excellent structural stability and cyclability,as its adsorption capacity remained at 36.98 mg·g^-1 after 5 cycles of adsorption-desorption.2.LIS precursor was synthesized using TiO₂ as the source of titanium,LiOH as the source of lithium,and triblock copolymer Pluronic F127 and hexadecylamine as soft templates,and then through pickling to obtain H₂TiO₃-4（HTO-4）with high surface hydrophilicity.In addition,H₂TiO₃-n（HTO-n）with different hydrophilicity were regulated and prepared by varying the synthesis routes and surfactants to investigate the correlation between the adsorption performance and morphology and structure of LISs.High hydrophilicity is conducive to reducing the mass transfer resistance between the adsorbent and Li⁺,promoting Li-H ion exchange and increasing adsorption rate.Therefore,HTO-4 with the best hydrophilicity exhibited the highest adsorption capacity(31.96 mg·g^-1)among all the samples and the adsorption rate constant is up to0.0412 g·mg^-1·min^-1.In simulated brine with metal ions concentration is about 200mg·L^-1,HTO-4 with a selective adsorption capacity of 21.14 mg·g^-1 for Li⁺exhibited remarkable selectivity.3.In view of the difficulty of recovering powdered LISs,Li₂TiO₃ membrane（LTO-NF）was prepared using electrospinning technology,with high hydrophilic LTO-4 as raw material,and then pickled to obtain HTO-NF.SEM images revealed that the morphology of LTO-NF exhibited a three-dimensional network structure,which facilitated the rapid diffusion of water phase in the membrane.Under the same adsorption conditions,HTO-NF exhibited faster lithium adsorption rate(K2=0.0423g·mg^-1·min^-1)compared to HTO-4 due to its fiber structure.The adsorption of Li⁺by HTO-NF was well-described by the Langmuir isotherm model,indicating a monolayer adsorption,with a theoretical maximum adsorption capacity of 47.33 mg·g^-1.Notably,HTO-NF showed excellent recovery and selectivity for Li⁺during adsorption,which has broad industrial prospects for lithium extraction from liquid lithium resources.