DHDECMP萃取硝酸铀酰的热力学研究

THE THERMODYNAMICS OF EXTRACTION OF URANYL NITRATE BY BIDENTATE ORGANOPHOSPHORUS EXTRACTANT DHDECMP

在288—343K的温度范围内,研究了不同浓度的DHDECMP(溶于DEB)自0.25—5摩尔硝酸介质中萃取铀(Ⅵ)的分配比与温度的关系.据此,用外推法首次获得了该萃取体系离子强度为零时的萃取热力学参数:K_t(1.15±0.10)×10~3,△H_t^0=27.5kJ.mol^(-1),△G^0=-17.5kJ.mol^(-1),△S°=33.5J.mol^(-1)K^(-1).

The distribution data for U(Ⅵ) from 0.25-5mol. L^(-1) nitric acid media with 1--40V% DHDECMP (dihexyl N,N-diethyl carbamoylmethyl phosphonate) in DEB (diethylbenzene) were determined in the temperature range 288--343K. From the variationof the distribution ratios with temperature the enthalpy changes associated with theextraction were evaluated. Using extrapolation technique the thermodynamic value ofthe enthalpy (ΔH°_t) for zero ionic strength was obtained to be -27.5 kJ·mol^(-1).The thermodynamic equilibrium constant (K_t), free energy ΔG°) and entropychanges (ΔS°) Were calculated at 25℃ to be 1.15×10~3, -17.5 kJ·mol^(-1) and -33.5J·mol^(-1). K^(-1), respectively.