Abstract: STUDIES ON SYNERGISTIC EXTRACTION MECHANISM OF AMERICIUM AND GADOLINIUM BY DHDECMPTBPKEROSENEAuthor Huang ZilinZhao HugenHu Jingxin (China lnstitute of Atomic Energy,P.O.Box 275(26), Beijing 102413) ABSTRACT The mechanisms of extracting Am3+ and Gd3+ in 0.05 mol/L HNO35.0 mol/L NaNO3 solution by TBPkerosene, DHDECMPkerosene and DHDECMPTBPkerosene have been studied. There exists synergism in the extraction of Am3+ or Gd3+ with DHDECMPTBPkerosene. The solvates are Am(NO3)33TBP,Am(NO3)33CMP,Gd(NO3)33TBP, and Gd(NO3)33CMP, respectively. The solvates in synergistic extraction are Am(NO3)33CMPTBP and Gd(NO3)32CMPTBP, respectively.The equilibrium constants K and thermadymic constants HG and S have been measured. The value of KGH and S of synergistic extraction of Am3+ is8.2103L7mol-7,-27kJ/mol,-23 kJ/mol,-13 J/molK and of Gd3+ is 6.3102 L6mol-6,-31 kJ/mol,-16 kJ/mol,-50 J/molK, respectively. Key words Synergistic extractionDHDECMPTBPAmGd