Features of palladium extraction by mono- and bidentate neutral organophosphorus compounds

Fission products, including the platinum group metals and, in particular, palladium, are currently of interest in radiochemistry. Extraction of Pd(NO3)2 by TBP, TlAP, TOPO, and bidentate extractants including the dioxides 40ct and 2Ph2Tol and the carbamoylphosphine oxide Tol2/Bu2 is studied. The position of the maximum Pd distribution coefficient as the acidity varies does not conform to generally accepted views that Pd(NO3)2 completely dissociates. The shift of the maximum toward low acidity can be explained by the presence of Pd in the aqueous phase as PdNO3+. Anomalous aryl strengthening is not observed for extraction by the bidentate extractants, indicating monodentate coordination. 3 refs., 4 figs