Preparation And Adsorption Performance Of HMTO/rGO-PAHG Hydrogel Lithium Ion-sieve Composite

In recent years,the wide application of lithium and its compounds in the fields of lithium power new energy,catalysts,medicine,ceramic glass and other fields has led to an upward trend of lithium consumption,driving the development of lithium resource recovery technology.At present,powdered lithium manganese oxide ion sieve is widely used in lithium recovery from aqueous solution.However,when lithium is desorbed in acidic solution,there are some problems about the adsorbent,such as dissolution loss,poor cycle stability,inconvenientance on operation and separation.Conductive lithium manganese titanate(H₄Mn_3.5Ti_1.5O₁₂)/reduced GO/polyacrylamide hydrogel composite(HMTO/r GO-PAHG)was prepared by in-situ thermal initiation polymerization.Ti-doped manganese oxide adsorbent was applied to reduce the dissolution of adsorbent in the process of removing lithium by acid pickling.The strength and toughness of the composites were improved by cross-linking r GO with polyacrylamide hydrogel,which combined with powdery H₄Mn_3.5Ti_1.5O₁₂ nanoparticles to form granular lithium ion-sieve.The stability and conductivity of HMTO/r GO-PAHG was improved for electrochemically assisted recovery of Li⁺.The materials were characterized by FE-SEM,IR,XRD,XPS and electrochemical methods.In this study,the method of electrochemically assisted recovery of lithium from aqueous solution was established.Under appropriate adsorption conditions(p H 10,45?,initial concentration of Li⁺is 300 mg·L^–1),the adsorption capacity of Li⁺by HMTO/r GO-PAHG can reach 51.54 mg·g^–1.The HMTO on HMTO/r GO-PAHG is transformed into LMTO during the adsorption process,and the adsorption process proved consist with the quasi-second-order kinetics and Langmuir model.In the desorption process,the LMTO/r GO-PAHG containing Li⁺was placed in 0.1 M HCl,the rapid desorption experiment of Li⁺was carried out by CV.When Mn⁴⁺was reduced to Mn³⁺,Li⁺was quickly desorbed in order to maintain electrical neutrality.When Mn³⁺oxidized to Mn⁴⁺,Li⁺can be exchanged by H⁺for their similar size,then the lithium ion-sieve can be quickly regenerated.The results indicate that HMTO/r GO-PAHG can be used for continuous recovery of lithium from aqueous solution,and regenerated during continuous adsorption and electrochemical desorption process.