Evaluation of kinetic parameters of uranyl acetate complexes in ethanolic solution by cyclic voltammetry

Abstract

The complexation of uranyl ion with acetate ions was investigated in 20% ethanolic solution by using cyclic voltammetry. The uranium formed 1:1 and 1:2 complexes with acetate ions. The values of log β1 and log β2 for uranyl acetate complexes were 2.05 ± 0.08 and 5.25 ± 0.06 respectively. The diffusion coefficient and heterogeneous rate constants for the reduction of uranyl ion at hanging mercury drop electrode in 20% ethanolic solution of acetate ions were 0.43 × 10−5 cm2 s−1 and 2.26 × 10−3 cm s−1, respectively. Thermodynamic parameters were also evaluated by finding the effect of temperature on the heterogeneous rate constants. The values of ΔH *, ΔS * and $$ \Updelta G_{298}^{*} $$ were 2.52 kJ mol−1, −43.8 J mol−1 K−1 and 15.57 kJ mol−1. The positive values of ΔH * and $$ \Updelta G_{298}^{*} $$ indicated that electrochemical reduction of uranyl ions in ethanolic solution of acetate ions is an endothermic and non-spontaneous process.