Synthesis of Polyporous Ion-Sieve and Its Application for Selective Recovery of Lithium from Geothermal Water

The widespread use of lithium-ion batteries has led to continuously increasing demands for lithium. In order to recover lithium from geothermal water, a novel composite lithium ion-sieve was synthesized and applied in this work. The stability of the material was successfully solved by granulating using acid-alkali resistant polyvinyl chloride as a binder, and its adsorption performances were also improved by using polyethylene glycol (PEG-6000) as a porogen to obtain a polyporous structure. When the developed material was applied for lithium separation from geothermal water, the adsorption capacity reached 12.84 mg/g at 328.15 K with an equilibrium time of about 12 h. The material can be well regenerated using 0.25 mol/L HCl to realize cycle use. The separation factors between Li⁺ and other co-existing ions were within the range of 273.58-521.28, and the attenuation of adsorption capacity after five cycles was no more than 2%. The high selectivity and reusability properties of the polyporous ion-sieve make the material a potential candidate for the selective separation and recovery of a low concentration of lithium from geothermal water.