EXTRACTION OF ACTINIDES AND LANTHANIDES FROM NITRIC-ACID SOLUTION BY MALONAMIDES

Solvent extraction from nitric acid solutions by three different malon amides; N,N'-dimethyl-N,N'-dibutyloctadecyl malonamide, N,N'-dimethyl- N,N'-diphenyltetradecyl malonamide and N,N'-dimethyl-N,N'-dicyclohexyl tetradecyl malonamide, dissolved in tert-butylbenzene, has been invest igated. The dependence on nitric acid concentration, nitrate concentra tion and malonamide concentration on the extraction of U, Th, Am, Eu, To and HNO3, is described. The influence of the different malonamide s tructures on the extraction behaviour is discussed. The phenylsubstitu ted malonamide, DMDPHTD, is able to extract metal species even from hi gh nitric acid concentrations. The experimental data indicate both a c oordination mechanism and an ion-pair extraction mechanism depending o n the nitric acid concentration.