| Due to its unique properties,rare earths have been applied and developed in many fields such as new materials,electronic products,new energy and petrochemicals,and have long become important strategic resources attracting worldwide attention.However,rare earth resources are non-renewable resources,and resources will be gradually exhausted as people explore,so new materials are researched to recover rare earth elements.In this paper,the surface ion-imprinted polymer of gadolinium ion was prepared by the surface ion-imprinting technique.The mesoporous material SBA-15 was synthesized by hydrothermal method.The mesoporous molecular sieves SBA-15 and MCM-41 were modified with phosphoric acid.The four adsorbents were characterized and their conditions were optimized,and the adsorption mechanism was discussed.(1)Using P123 as a template and ethyl orthosilicate as a silicon source,SBA-15 mesoporous molecular sieves were prepared under acidic conditions using hydrothermal synthesis.The prepared SBA-15 was characterized by transmission electron microscopy and specific surface analysis.The appearance of SBA-15 mesoporous molecular sieves is uniform and flat with rich pore structure,and SBA-15 has a large specific surface area,and its surface area is 667.271 m2/g.The experimental data are analyzed.The adsorption process of SBA-15 for gadolinium ion conforms to the Langmuir adsorption model,and the adsorption process can be described by a quasi-second-order kinetic model.In repeated elution experiments,2mol/L hydrochloric acid had the best desorption capacity for SBA-15,and SBA-15 had good stability and reusability.(2)With SBA-15 as the carrier and polyethyleneimine as the functional monomer,a Gd-IIP/SBA-15 fluorene ion-imprinted polymer was synthesized and characterized.Gd-IIP/SBA-15 was used as an adsorbent to adsorb gadolinium ion.The experimental conditions were optimized and the best conditions were found:the pH of the solution was 5,the initial concentration of gadolinium ion was 300 mg/L,and the adsorption temperature was 45℃.The adsorption equilibrium was 60 minutes,and the saturated adsorption capacity was 191.33 mg/g.The adsorption process of Gd-IIP/SBA-15 for gadolinium ion conforms to the Langmuir isotherm adsorption model,and the adsorption reaction is spontaneous and conforms to the quasi-second-order kinetic model.The experimental research on the selectivity of the adsorbent showed that,compared with Gd-NIP/SBA-15,Gd-IIP/SBA-15 has good selectivity.Experiments on the elution and regeneration performance of the adsorbent showed that 2 mol/L hydrochloric acid had the best elution effect.Gd-IIP/SBA-15 has good stability and can be reused.(3)P-SBA-15 was obtained by modifying the surface of SBA-15 with phosphoric acid.By infrared spectrum analysis,it was found that phosphoric acid had been loaded on the surface of SBA-15 mesoporous molecular sieve.P-SBA-15 has excellent adsorption capacity and kinetic performance.Under optimized conditions,the saturated adsorption capacity of P-SBA-15 for gadolinium ion adsorption is 1338.57 mg/g,and the adsorption time is only 5 minutes.Adsorption of ions is very rapid.And it has very good elution effect with hydrochloric acid,P-SBA-15 has good stability and good recyclability.P-MCM-41 was obtained by treating MCM-41 with the same method.The optimum conditions were as follows:the initial concentration of gadolinium ion was 500 mg/L,the pH of the solution was 5,the adsorption temperature was 45℃,and the adsorption time was 4 minutes.Under the optimum conditions,the adsorption capacity of P-MCM-41 on gadolinium is 1212.80 mg/g,while that of MCM-41 is 450.34 mg/g and the adsorption time is 30 minutes.It can be seen that P-MCM-41 has high adsorption efficiency and large adsorption capacity. |
PDF Full Text Request