THE STUDY OF THE EXTRACTION OF URANIUM(IV) CHLORIDE WITH CROWN ETHERS

In this paper, results are reported on the extraction behaviors of uranium (IV)by 31 kinds of crown ethers with various substituting groups from hydrochloricacid solutions. Results indicate that DCH's (dicyclohexl-crown ethers) in 1,2-dichloroethane provide best extraction of uranium (IV). The effects of the concen-trations of DCH, U (IV) and HCl in both phases on the extraction are alsostudied. It is found that U (IV) is not extracted in 5.0 M HCl by DCH, but thedistribution coefficients of U (IV) increase rapidly when HCl concentration isincreased to 8.0--8.5M. Using the slope method and the method of isomolarseries, the extracted species are identified as H_2UCl_6·2DCH. The extraction capaci-ties of five DCH's for uranium decrease in the order: DCH--27C_9, DCH--24C8,DCH--18C6, DCH--30C10, DCH--21C7. Experimental results indicate that theextraction reaction is as follows: U~(4+)+2H~++6Cl~-+2DCH=H_2UCl_6.2DCH