Extraction of Cesium and Strontium from Nitric Acid Solutions with Crown Ethers in Heavy Diluents

A study was made of the ability of crown ethers in heavy polar organic diluents (chloroform; 1,2‑dichloroethane; bis(2-chloroethyl) ether; 1,1,7-trihydrododecafluoroheptyl alcohol) to extract cesium and strontium from nitrate solutions. It was shown that the use of bis(2-chloroethyl) ether as a polar diluent in the extraction with dibenzo-21-crown-7 and 4,4'(5')di-tert-butyldibenzo-18-crown-6 leads to sufficiently high distribution coefficients D_Cs of cesium from solutions with a nitric acid concentration of 1–5 mol/dm³. When extracting strontium with dicyclohexyl-18-crown-6, the highest distribution coefficients D_Sr were achieved using chlorine-substituted hydrocarbons and bis(2-chloroethyl) ether with a maximum extraction of 1–3 mol/dm³ HNO₃, depending on the diluent used. Extraction systems based on selective crown ethers in a mixture of solvents were proposed for the co-extraction of cesium and strontium from nitric acid solutions of complex chemical compositions.