NEW SELECTIVE SORBENTS FOR THE EXTRACTION OF ALKALI METAL IONS

Macromolecules with crown ether groups represent a fundamentally new type of sorbents whose active centers are ligands that retain electroneutrality during simultaneous binding of cations, anions or organic compounds. The aim of this work is to study the conditions for the preparation of polymeric sorbents containing diaminodicyclohexyl crown-ethers and to investigate the activity of these sorbents with respect to the extraction of alkali metal cations. Chemical grafting of cycloaliphatic crown ethers onto a macroporous chloromethylated copolymer of styrene and divinylbenzene was carried out. Under selected conditions, diaminodicyclohexyl-18-crown-6 produced polycrown- ethers with a content of crown-ether groups of 1.42 mmol/g, while diaminodicyclohexyl-24-crown-8 produced a content of macrocyclic groups of 1.24 mmol/g. The recovery of alkali metals under static conditions by grafted type sorbents based on different macrocycles has been investigated. High values of distribution coefficients of alkali metals (Na+, K+, Cs+) by synthesized sorbents in acidic medium are shown. The following selectivity series were found for the sorbent with diaminodicyclohexyl-18-crown-6 fragments: К+ ˃ Cs+ ˃ Na+, and for the sorbent with diaminodicyclohexyl-24-crown-8 fragments: Cs+ ˃ K+ ˃ Na+. The efficiency of the obtained sorbent for the extraction of alkali metal cations was shown.