Sorption purification of solutions of alkali metals from impurities of alkaline-earth and non-ferrous metals

Abstract

The article is devoted to the study of the sorption of magnesium, calcium, nickel, copper, cobalt and zinc ions from solutions of alkali metal salts - NaHCO₃, LiHCO₃ and LiCl, using various ion exchangers: sulphocationite, phosphoric acid and carboxyl cation exchangers, and chelated iminocarboxyl ion exchangers. The results of the experiments in batch conditions showed that the sulfocathionite TOKEM 308 (analogue KU-2×8, Russia) almost does not sorb the non-ferrous metals and magnesium from the NaHCO₃ solution. All the other sorbents has a high sorption capacity with respect to Ni, Ca, Mg, and Co ions. The sorption of copper is the worst, due to the formation of strong carbonate copper complexes. Iminocarboxylic chelate sorbents - Amberlite IRC 748 («Rohm and Haas», USA), Purolite S930 (Purolite, UK) and AXIONIT 3S (JSC Axion RDM, Russia) has  the maximum values ​​of the batch exchange capacity with respect to Ca, Ni, Cu, and Zn ions in LiHCO₃ solution. For the sorption purification of LiCl solution (pH 1.4) from impurities of calcium, magnesium, copper and nickel ions, iminocarboxyl ionites are also the most acceptable, however in this case the capacity of all the sorbents is several times lower than in the case of weak alkaline solutions of NaHCO₃ and LiHCO₃.

Results of flow rate experiments on the purification of NaHCO₃ and LiHCO₃ solutions from the impurities of magnesium, calcium, nickel, copper, as a whole, confirmed the data of batch experiments on the maximum efficiency of iminocarboxyl ion exchangers.

The experiences has demonstrated that the iminocarboxyl chelate ionites are highly promising sorbents for deep purification of alkali metal salts from impurities of alkaline earth and non-ferrous metals