Work

Determination of the Activity Coefficients of Components in a Di-2-ethylhexylphosphoric Acid–n-Hexane Binary System Using Gas Chromatography

Year: 2025

Type: article

Abstract: The thermodynamic properties of di-2-ethylhexylphosphoric acid (D2EHPA) in organic solvents are critical for optimizing metal extraction processes in hydrometallurgy, necessitating precise determination of activity coefficients in binary systems such as D2EHPA–n-hexane. This study was devoted to the determination of n-hexane’s concentrations in the vapor phase over D2EHPA solutions at 293.0 K using gas chromatography (GC) and isopiestic (IP) methods. Comparison with literature data confirmed the superior reliability of GC measurements at low n-hexane concentrations. The experimentally determined activity coefficients of hexane, obtained via GC, served as the initial input parameters for UNIFAC modeling. The optimized interaction parameters were 1144 ± 25 (CH2-HPO4) and 228 ± 50 (HPO4-CH2), with the infinite dilution activity coefficient for D2EHPA γ∞=22.1. These results experimentally clarify the non-ideal behavior of D2EHPA–n-hexane mixtures, establishing a validated thermodynamic modeling framework for organophosphorus extractant systems. This work establishes a fundamental basis for investigating ternary systems, such as D2EHPA–aliphatic solvent–aromatic solvent and D2EHPA–metal complex–solvent systems, paving the way for enhanced liquid–liquid extraction efficiency.

Source: Chemistry

DOI: 10.3390/chemistry7030092

Authors: Vladimir Glebovich Povarov, Olga Vladimirovna Cheremisina, Daria Artemovna Alferova, Aleksandr Tomasovich Fedorov

Institution: Saint Petersburg Mining University

Language: English

Topic: Phase Equilibria and Thermodynamics

Subfield: Physical and Theoretical Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,172

Funder: Ministry of Science and Higher Education of the Russian Federation