Study On Preparation And Application Of Titanium Composite Lithium Ion Sieve

The sea and bittern water is rich in Li⁺,which is far more than the amount of lithium ore in Li⁺.In order to solve the technical problems of extracting lithium from salt brine,it meets the increasing demand for lithium in China,appropriate separation methods are required.The titanium ion sieve has the characteristics of cyclic stability,selectivity and environmental protection.It has broad application prospects in the extraction of lithium from brine.However,there are still some problems in the study of titanium ion sieve.In order to improve the performance of the ion sieve,this paper introduces the preparation of zirconium doped titanium composite ion sieve.Firstly,Li₄Ti₅O₁₂ was synthesized by hydrothermal method,carbon sphere template hydrothermal method and solvothermal method,and the crystal structure of titanium oxide was analyzed by XRD diagram,and the surface morphology was analyzed by SEM.The experimental results show that the sample synthesized by solvothermal method is a spinel structure with sharp diffraction peaks,high strength and good crystallinity.The composite oxide is a three-dimensional network structure formed by an elliptical hole,and the hole wall is interconnected into a space system.So the solvothermal method is chosen as the next experimental method.Analysis of the influence of zirconium doped proportion,citric acid complex solvothermal synthesis of lithium titanium zirconium oxide in addition,calcination temperature and other conditions on the crystal structure,so as to determine the optimum experimental conditions of the synthesis of lithium titanium zirconium composite oxides.By XRD and SEM analysis,we can see that the prepared composite oxides are of spinel structure and have the space structure of nano pores,pore size is 40 nm.Titanium composite ion sieve was prepared that hydrochloric acid was the lithium removal agent by modified experimental.we know the rate of the relationship between HCl concentration and extraction of Li⁺and Ti⁴⁺.When the concentration of hydrochloric acid was 0.16 mol/L,the leaching rate of Li⁺ was as high as,while the extraction rate of Ti⁴⁺ was less than 0.48%.So to determine the suitable concentration of hydrochloric acid is 0.16 mol/L.The factors affecting the IE-H exchange capacity of ion sieve,such as pH value,lithium ion concentration and temperature,were determined by single factor and orthogonal experiments.Under the experimental conditions the saturated exchange capacity reached 7.35 mmol Li⁺/g,after several cycles,the variation range of ion sieve saturated exchange capacity of Li⁺ was less than 0.02%,so the adsorption cycle stability of preparation of ion sieve is very good.Through the ion exchange selectivity and pH titration curve,it is known that the lithium ion sieve has good memory and ion exchange selectivity to Li⁺.The ion exchange isotherm experiments were carried out to obtain the mass action of ion exchange reaction.The thermodynamic equilibrium constant can be calculated by using the Pitzer electrolyte theory and the thermodynamic correlation coefficient.The thermodynamic parameters such as standard free energy and standard enthalpy change can be calculated by using the formula of chemical thermodynamics.We can get: in the range of experimental conditions,?H⁰=-6642.97 J/mol <0,?S_15?⁰=-3.7953 J/?mol·K???S_25?⁰=-5.1912 J/?mol·K?? ?S_35?⁰=-5.7160 J/?mol·K?,which shows that the titanium complex type ion sieve Li⁺ion exchange adsorption reaction is exothermic and spontaneous.The powdered zirconium doped titanium lithium ion sieve is granulated so as to obtain a granular lithium ion sieve The static exchange capacity of Li⁺ is 17.77mg/g,and the switching capacity of Li⁺ is 13.42mg/g in column switching,and the application effect is better.