EXTRACTION OF EU(III) BY DINONYLNAPHTHALENESULFONIC ACID AND SYNERGISTIC EFFECTS OF CROWN-ETHERS AND TRIOCTYLPHOSPHINE OXIDE

The extraction of Eu(III) by dinonylnaph-thalenesulfonic acid (HDNNS) in benzene from nitrate and perchlorate solutions has been investigate d. For nitrate solutions the ionic strength of the aqueous phase was k ept constant at 0.1M using NaNO3-HNO3 mixtures. The Eu distribution wa s measure at different temperatures. The following stoichiometric form ulae for the Eu species in benzene were derived: Eu(NO3) (H-n-1(DNNS)( n))(2) and Eu(H-n-1(DNNS)(n))(3), from the nitrate and perchlorate med ium respectively (n being a small number, e.g. 1, 2 or 3). The equilib rium constants were calculated and the thermodynamic parameters of the system were determined. When adding dibenzo-24-crown-8, dicyclohexyl- 18-crown-6 or trioctylphosphine oxide, no synergism, but rather antago nism was observed.