Study On Preparation Of Bio-template Adsorbent And Selective Adsorption And Separation Of Lithium Ions

In recent years,lithium and its derivatives have served as a critical strategic resources,and the development of lithium resources has also entered the gold stage in all areas of our country.With the development of batteries,glass,grease,refrigerant,and chemical reagents,the demand for lithium is also growing rapidly,and the impact of lithium mine resources to the environment is irreversible,not only with current sustainable development.In contrast,it will cause the environment to deteriorate.However,most of the lithium resources in nature are present in seawater and salt lakes.How to selectively adsorb and separate lithium ions,causing more and more research.Cellulose is not only everywhere in plants,but even some bacteria and animals are no exception.Therefore,cellulose is a more easily obtained green regenerative resource.The use of cellulose nanocrystals（NCC）,bacterial cellulose（BC）,and its modified product,a series of adsorption materials with selective adsorption and separation of lithium ions are prepared as biological templates,and through rich characterization methods and one The series of adsorption experiments conducted preliminary discussions and analysis.The main research contents are as follows:（1）Hydrochloric acid（HCl）and tetraethyl Tetraethyl Titanate（TEOT）are fully stirred and mixed until TEOT is hydrolyzed,and NCC is introduced to stir,dry and calcine to obtain precursor LTO-NCC,and persulfate（Na₂S₂O₈）is used as eluent to elute and exchange Li⁺in LTO-NCC,the lithium ion sieve adsorbent（NTO-NCC）with a layered structure was formed.The material is discussed and analyzed by the microstructure of the test material.According to the data obtained from adsorption experiment,the maximum adsorption effect of NTO-NCC can reach 34.56 mg^-1 and the distribution coefficient of Li⁺reaches 2436.95,which is several times the other competitive ions.In 5repetitive adsorption experiments,it is always possible to maintain more than83%of its maximum adsorption capacity.The above studies may prove that the method of providing biological templates using NCC is of great significance for the preparation of new lithium ion sieve suction agents,providing a foundation for the next study.（2）In order to further improve the stability of lithium ion sieve adsorbents,we explored the use of bacterial cellulose as a biological template to construct titanium dioxide（Ti O₂）with BC network structure,and then calcined it after hydrothermal reaction with lithium hydroxide（Li OH）to prepare mesoporous titanium lithium ion sieve precursor（LTO-BC）.The lithium ion sieve（HTO-BC）with selective adsorption for lithium ions was obtained after pickling.The lithium adsorbent prepared by this method is more stable than the lithium ion sieve prepared by cellulose nanocrystals,which is an effective exploration to optimize the preparation technology of titanium lithium ion sieve.（3）By virtue of the excellent three-dimensional network structure of BC,the tannic acid modified BC was mixed with Al（OH）₃,Li OH and water for constant temperature stirring,and the lithium-aluminum hydrotalcite was grown on the modified BC membrane,and the membrane-like lithium ion adsorbent（LDHs-BC）was obtained.Compared with previous adsorbents,it has a higher adsorption capacity for lithium ions at a relatively low concentration of lithium ions.The morphological composition and adsorption mechanism of LDHs-BC were systematically studied by various characterization methods and adsorption experiments.The results show that LDHS-BC can effectively extract Li⁺membrane adsorbent from seawater and salt lake brine,and it has a high application prospect in the later industrial continuous production.