Li+ EXTRACTION FROM AQUEOUS SOLUTIONS BY PVDF-BASED MEMBRANES CONTAINING PARTIALLY PROTONATED POTASSIUM POLYTITANATE

Abstract

Extraction of lithium from natural aqueous solutions as alternative source of this chemical element becomes the actual and demanded task. Among the variety of known methods, ion exchange adsorption is considered to be suitable both in terms of the final product purity and economic efficiency of the technological operations. Compounds with layered and tunnel structures are promising ion-exchange materials. In this study, the partially protonated potassium polytitanate is investigated as the Li+ ions adsorbent. This amorphous substance characterized with the K1.3H0.7Ti4.1O9 chemical composition is synthesized by acid treatment of X-ray amorphous layered potassium polytitanate K2O·nTiO2 (n = 4.1). The PVDF-based membranes filled with the K1.3H0.7Ti4.1O9 powder are prepared by the phase inversion technique. Using the kinetic and isotherm technique, it is shown that a use of the pseudo-first order model (qe = 0.5 mg/cm2; k1 = 0.014 min-1) and the Freundlich adsorption model (KF = 0.028 (L)1/n(mg)1-1/n/cm2; n = 1.595) are the best models to describe the interaction of the obtained membranes with lithium ions. The calculated parameters of the adsorption capacity, distribution coefficient (Kd), separation factor (α) and concentration factor (CF) confirm a high lithium ions selectivity of the investigated ion-exchange composite in the presence of sodium and potassium ions. The obtained results show that the PVDF-based membrane with partially protonated potassium polytitanate is a good candidate for selective lithium extraction from natural aqueous solution. For citation: Vikulova M.A., Maximova L.A., Rudyh V.Yu., Gorokhovsky A.V. Li+ extraction from aqueous solutions by PVDF-based membranes containing partially protonated potassium polytitanate. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 62-69. DOI: 10.6060/ivkkt.20246705.6969.