Research On Synthesis Of γ-AlOOH With Different Morphologies And Its Adsorption Performance For Congo Red/Li~

γ-AlOOH has been considered as an excellent adsorbent material for adsorption of dye wastewater because of its low cost,excellent biocompatibility,good chemical stability,high surface properties and morphology controllability.Aluminum-based layered adsorbents can achieve lithium extraction from lithium-containing brines.γ-AlOOH,as the precursor of aluminum-based adsorbents,has a strong influence on the adsorption performance in terms of its morphology and pore size.To improve the adsorption performance ofγ-AlOOH,it is important to prepare smaller-scale powderγ-AlOOH with different morphologies as adsorbent.In this paper,Microspheres,Hollow and Nucleoshellγ-AlOOH were prepared by spray drying method,template method and ionic liquid method,and the adsorption performance of different morphologies ofγ-AlOOH on Congo red was investigated respectively.the adsorption performance of Microspheres and Nucleoshellγ-AlOOH as precursors of lithium-aluminum layered adsorbent was investigated.The main studies are as follows.（1）Microspheresγ-AlOOH was prepared by spray drying method.over 90%removal of adsorbent was achieved in different concentrations of acidic Congo red solution,and the adsorption equilibrium was reached within 20 min.The adsorption process was consistent with the pseudo-second-order and Langmuir model.The activation energy of adsorption was 21.11k J mol^-1,and the maximum adsorption amounts of Microspheresγ-AlOOH on Congo red was1131.94 mg g^-1,it had excellent cyclic adsorption performance.（2）Hollowγ-AlOOH was prepared by the template method,which was hollow microspheres and could reach 88%removal rate at high concentration(1200 mg L^-1)of Congo red solution.The activation energy of adsorption during the adsorption process was 23.47 k J mol^-1,which was physical adsorption with a maximum adsorption capacity of 2241.15 mg g^-1,and the adsorption reaction was heat-absorbing and spontaneous.The sample had excellent cyclic adsorption capacity.（3）Nucleoshellγ-AlOOH was synthesized by a simple and effective ionic liquid method.It has a dense nanosheet on the surface,and a layered structure with smaller microsphere particles inside.The maximum adsorption capacity was 3881.46 mg g^-1,its removal rate could reach 92%at high concentration(2000 mg L^-1)of Congo red solution.The adsorption process was conformed to Langmuir and pseudo-second-order model and was self-generating,exothermic and an activation energy of 24.17 k J mol^-1,it had excellent cyclic adsorption capacity.（4）On the basis of Chapters 3 and 5,Microspheresγ-AlOOH and Nucleoshellγ-AlOOH were used as precursors for the preparation of Li-Al bilayer hydroxide adsorbents（A and B）with the active composition of Li Al₂（OH）₇-x H₂O,and the maximum adsorption amounts of Li⁺were 12.08 mg g^-1 for adsorbent A and 9.89 mg g^-1 for adsorbent B.In the presence of multiple cations coexist,Li⁺can be well separated from Na⁺,K⁺and Mg²⁺.In the synthesis process,Li⁺was embedded inγ-AlOOH octahedra to form a layered structure,and then Li⁺was washed out with water to obtain Li-Al bilayer hydroxide lacking the regular void structure of Li⁺.In the adsorption process,Li⁺in solution filled the Li⁺vacancies in the adsorbent to achieve a better adsorption effect.