Laboratoire de Chimie Analytique et Électrochimie

1. Laboratoire de Chimie Analytique et Électrochimie In this work, we have used the O.E.C.M. for determining the self-diffusion data of the lanthanide trivalent ion 152Eu (III) in large range of concentration of supporting lanthanide electrolytes. In order to minimize the hydrolysis, association and complexing, we have used an acidic medium (pH 2.50). The graph D = f (vC) for Es3+ ion can be compared to those of 241Am3+ and 152Eu3+ obtained under the same conditions. Moreover, it may be argued that the Es3+, Am3+ and Eu3+ aqueous ions in solution have the same hydration as 5f and 4f trivalent ions in the absence of hydrolysis, complexing or ion pairing at pH 2.5. The present study contributes to demonstrate the analogy of solvation structure of trivalent actinide ions in aqueous solutions at pH 2.5 with that of lanthanide trivalent ions as an aid for deducing thermodynamic properties. C o n c l u s i o n Hydration of the lanthanide ions 152Eu(III), 153Gd(III) and 170Tm(III) in aqueous solutions at 298 K and similarity with the transplutonium element ions 254Es(III), 244Cm(III), 241Am(III), 249Cf(III) and 249Bk(III) N. Ouerfellia, D. Dasb,*, H. Latrous a, M. Ammar a and J. Oliver c a Lab. de Chimie Analytique et Électrochimie. Département de Chimie. Faculté des Sciences de Tunis, Campus Universitaire. 2092 El Manar, Tunisia. bDepartment of Chemistry, Dinhata College, Dinhata-736135, Cooch-Behar, West Bengal, India. cOak-Ridge, National Laboratory, Tennessee, U.S.A..,* Corresponding Author , E-mail: debu_nbu@rediffmail.comThis paper is intended to be in the memory of M. Ammar (F.S.T. Tunisia) and J. Oliver (G.T.Seaborg co-worker in T.R.L. Oak-Ridge National Laboratory). Ionic self-diffusion coefficients data for 152Eu (III) and 241Am (III) are reported for concentrations of a supporting electrolyte of Gd(NO3)3-HNO3 or Nd(ClO4)3-HClO4 aqueous solutions up to 1.14 mol.L-1 at 25°C. The open-end capillary method (O.E.C.M.) is used for the determination of the ionic self-diffusion coefficients at pH = 2.50 labelled with tracers 152Eu (III) and 241Am (III). A study of Walden’s law behaviour at variable concentrations can provide an interesting discussion for an eventual expression if the parameter b. The similarity in the ionic transport process (4f and 5f elements) leads us to conclude as a further consequence, it may be argued that of 152Eu (III) and 241Am (III) ions have the same hydration as a tripositive ion (with a comparable ionic radius) in the absence of hydrolysis, association and complexing (by choice of an acidic medium at pH 2.50). Introduction Extension of the Onsager limiting model (parameter b) Variation of (D) as a function of square root of supporting electrolyte (√c) in dilute aqueous solutions and deviation to linear Onsager limiting law of some trivalent lanthanide and actinide ions at 25°C and pH 2.5. Self-diffusion coefficients D / (10-6 cm2.s-1) in mean and concentrated solutions at 25°C of some trivalent lanthanide and actinide ions as a function of square root of molarity C / (mol.L -1). Actinide - Lanthanide ions Similarity Walden Product Similarity of Structure Selfdiffusion - Viscosity Correlation Walden’s product D.h versus square root of molarity m. D : self-diffusion coefficients of tracers Ln (III) ions ; h : viscosity of supporting electrolytes of Gd(NO3)3-HNO3. Hydration radii Hydration number 13 water molecules of Eu (III) and Am (III) ions