Physico-chemical properties of binary systems involving modifier (methanol or propionic acid) and an acidic extractant di (2-ethylhexyl) phosphoric acid (DEHPA): volumetric, acoustic and viscometric routes

Abstract

In solvent extraction, a suitable modifier, basically polar liquid is used with extractant like DEHPA, TBP, TOPO and MIBK to enhance the efficiency in extraction processes. This paper is related to the study of physico-chemical properties of polar – polar binary mixtures at 303.15K and 0.1 MPa. Molar volume, free volume, isentropic compressibility, intermolecular free length, specific acoustic impedance, relaxation time, Rao’s constant, Wada’s constant, absorption coefficient have been calculated from the experimentally measured data of density, ultrasonic velocity and viscosity of pure components and binary mixtures of methanol/ propionic acid + DEHPA. In addition, excess molar volume, excess Gibb’s energy of activation of viscous flow, deviations in viscosity, isentropic compressibility, free volume, intermolecular free length and acoustic impedance were also computed from the experimental data. The observed variations of excess/deviation functions with the composition of DEHPA have been discussed in terms of molecular interaction between unlike molecules in two binary mixtures due to chemical, physical and structural effects. It is found that the molecular interaction of methanol with extractant DEHPA is better than that of propionic acid and so methanol may be used as a suitable modifier with DEHPA in the solvent extraction process.