SELECTIVE SORBENTS BASED ON DIAMINODICYCLOHEXYLCROWN ETHERS

Abstract

Introduction. Macromolecules with crown ether groups are a fundamentally new type of sorbents whose active centers are ligands that retain electrical neutrality in the process of simultaneous binding of cations, anions, or organic compounds. The purpose of this work is to create new selective sorbents based on diaminodicyclohexylcrown ethers and to study their complexing properties with respect to alkali metal ions. Methodology. To study the composition and properties of the products of the synthesis of crown ether-containing sorbents, chemical and physicochemical methods of analysis were used: infrared spectroscopy, atomic absorption spectrophotometry. Results and discussion. Chemical grafting of cycloaliphatic crown ethers onto a macroporous chloromethylated copolymer of styrene and divinylbenzene has been carried out. Under the chosen conditions, when using diaminodicyclohexyl-18-crown-6, polycrown ethers were obtained with a content of crown ether grains of 1.42 mmol/g, when using diaminodicyclohexyl-24-crown-8, the content of macrocyclic groups was 1.24 mmol/g.  The extraction of alkali metals under static conditions by grafted sorbents based on various macrocycles has been studied. The high values of the distribution coefficients of alkali metals (Na+, K+, Cs+) by the synthesized sorbents in an acidic medium are shown. The following selectivity series were found for the sorbent with diaminodicyclohexyl-18-crown-6 fragments: K+ ˃ Cs + ˃ Na+, and for the sorbent with diaminodicyclohexyl-24-crown-8 fragments: Cs+ ˃ K+ ˃ Na+ metals. Conclusion. The efficiency of extracting metal ions from aqueous solutions containing Crown esters is affected by the presence of amino groups. It is known that the amino group promotes the formation of a polymer that swells in water. It was noted that the use of sorbents based on polymers that swell in water when metal salts are removed from the aqueous medium leads to an increase in the sorption capacity of sorbents by facilitating the access of metal ions in water to the active areas of the immobilized sorbent.