Study of the interaction of Pu(IV) and Np(IV,V,VI) with Fe hydroxides to predict the behavior of actinides in environmental media

Abstract

A Mössbauer effect method was used to study the formation of mixed hydroxides in the alkaline coprecipitation of Pu(IV) or Np(IV) with Fe(III). The Mössbauer spectra of mixed 239 Pu(IV)-Fe(III) and 237 Np(IV)-Fe(III) hydroxide samples differ from that of pure α-FeO(OH) formed in aqueous basic solutions. Alkaline coprecipitation of Np(V) or Np(VI) with Fe(III) hydroxides does not produce the mixed hydroxides shown by Pu(IV) or Np(IV) with Fe(III). The general Mössbauer spectral parameters of the Np(V),(VI)-Fe(III) hydroxides are similar to those of pure α-FeO(OH).