Synthesis and Sorption Properties of New Selective Sorbents Based on Crown Ethers

Introduction. Macrocyclic compounds such as crown ethers and their analogs are able to selectively bind metal ions due to donor atoms in the ring, which makes them promising for the development of sorbents. Polymers with nitrogen- and sulfur-containing crown ethers are of particular interest because of their high selectivity and stability. The aim of this work is to synthesize sorbents based on aza- and thiacrown-ether compounds forming selective complexes with metal ions in solution. The synthesis, structural characterization and sorption properties of polymeric sorbents based on macrocyclic compounds containing nitrogen and sulfur atoms - aza- and thiacraun- esters - are considered in this work. These compounds have the ability to form stable and selective complexes with metal ions due to the presence of donor atoms (nitrogen, oxygen and sulfur) in their ring structure. The work focuses on the advantages of immobilization of macrocyclic ligands on a polymer matrix in order to increase their stability, reduce toxicity and improve sorption characteristics. Methods and Materials. Immobilization was carried out on a chloromethylated copolymer of styrene and divinylbenzene by nucleophilic substitution in dimethylformamide. Various crown ether derivatives were successfully anchored: monoaza-15-crown-5 (MA15K5), diaza-18-crown-6 (DA18K6), and mixed aza-thiacrown ethers (DADT18K6 and DATT18K6). The structural changes were confirmed by IR spectroscopy and optimal reaction conditions in terms of temperature, time and reagent ratio were established. Studies and Results. The obtained polymers were investigated for their ability to sorb metal ions (Na⁺, K⁺, Ag⁺, Hg²⁺, Pb²⁺) in aqueous and methanol media. The sorption efficiency was found to depend significantly on the structure of the macrocycle, especially on the number of sulfur atoms, as well as on the nature of the solvent. Polymers containing DADT18K6 and DATT18K6 showed the highest affinity to Hg²⁺ and Pb²⁺ ions. The obtained results confirm the promising application of immobilized aza- and thiacraun ether sorbents for selective extraction of metal ions and in the tasks of environmental protection.