| Lithium is an important metal resources, it occupies a pivotal position in military and civilian aspects. There are rich resources of lithium in China, mainly in the form of Salt Lake brine and other liquid lithium ore. The ion exchange method is a simple, economical and environmentally friendly mining approaches, it is expected to become a new method for the extracting Li because it overcome the traditional methods certain deficiencies. A lithium ion-exchanger with good performance is a key point of the development of ion exchange method. Inorganic metal oxide Li ion-exchangers have good exchange performance, is currently a hot topic, the metatitanic type Li+ ion-exchanger is one of the most typical kind. In this paper, on this basis, to do the following aspects:Firstly, learning the distribution and application of lithium resources in our country,and analyzing the prospects of ion exchange method by comparing various liquid lithium mining methods. Discuss the current status of lithium ion-exchangers and materials synthesis.Tetrabutyl titanate, lithium acetate as raw material, ethanol as solvent, acetic acid as hydrolysis inhibitor, Li2TiO3 powder, the precursor of Li ion-exchangers were prepared by sol-gel method, Exploring the effect of dosage of acetic acid, aging and calcination conditions on the product. It found that molar ratio of acetic acid and tetrabutyl titanate is 5,aging 8 d at room temperature, calcining the precursor 8 h at 600 ℃, to obtain a single phase Li2TiO3 nano-powders with homogeneous particle and intact morphology, particle size 300-400 nm.The Li ion-exchanger Li2TiO3(H) was prepared by treated Li2TiO3 precursor use Hydrochloric acid, determine the effect of acid concentration, temperature and time on the solution loss and Li extraction rate. When treat on certain conditions(0.1 mol × L-1hydrochloric acid, 45℃ and 20 h), solution loss lower than 0.15%, Li extraction rate about97.5%. The surface area, primary mesopore volume and pore size of Li2TiO3(H) are38.8268 m2×g-1, 0.0834 cm3×g-1, 2.0 nm respectively, uniform and loose particle size about500 nm, the XRD patterns of Li2TiO3(H) and Li2TiO3 significant difference, but the former having active ion exchange sites.Static adsorption experiments were carried out to investigate adsorption of Li+ in Li2TiO3(H) ion-exchanger, and to determine the influence of pH, reaction time, initial concentration and temperature on the adsorption capacity, the reaction mechanism are discussed and the kinetic, thermodynamic and isothermal absorption models parameters for the reaction are obtained. The maximum adsorption capacity, 32mg×g-1, was obtained at the optimum adsorption conditions: pH=12.8, initial concentration 200 mg Li × L-1, shock absorption 3 h at 35 ℃. Adsorption process is spontaneous and exothermic, The kinetics and isothermal data fitted the pseudo-second and Langmuir model, respectively. Li2TiO3(H)showed good Li+ ion exchange performance.Under suitable adsorption and desorption conditions, to test the cyclic and selectivity of Li2TiO3(H). the adsorption capacity eventually stabilize at 22 mg × g-1 after 5 times adsorption and desorption, the capacity decreased gently 23%. Solution loss in single cycle was maintained below 0.2%, the material exhibit a property of stable circulation. XRD and SEM results substantially unchanged before and after experiment. In the system of five kinds of alkali metals and alkaline earth metal ions coexist with equal amount of substance,Li2TiO3(H) is good at pick up Li+, the separation factor of Li+ and Na+, K+, Mg2+, Ca2+ are 22.85, 30.18, 116.47, 141.09, respectively. |
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