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A new semi-empirical model for correlation of solubility of ligands in supercritical carbon dioxide

K. Subashree, R. Shruti Krishna, K. C. Pitchaiah, Rahul Kumar, G. Chandrasekhar, A. Suresh, and N. Sivaraman

Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute (HBNI), Kalpakkam, India



Received: 27 September 2023  Accepted: 11 January 2024


Model correlation of solubilities of task-specific ligands in supercritical carbon dioxide medium (SC-CO2) plays an important role in development of green separation methods for recovery of metal ions. In the present study, a new semi-empirical model was proposed to predict the solubility of ligands in SC-CO2 medium and is a modified version of existing Chrastil model. The correlation ability of new model was compared with existing density-based models (Chrastil, Adachi–Lu, del Valle–Aguilera, Sparks, Sung–Shim, Mendez-Santiago–Teja, and Bartle). New model evaluation studies were carried out using reported solubility data of 31 metal ion-specific ligands. The prediction ability of new model was compared using different objective functions, coefficient of determination (R2), absolute average relative deviation (AARD), and Akaike information criteria. The proposed model is accurate for correlating the solubility of ligands with a global AARD of 8.47%. The model was found to be most suitable for predicting the solubility of organophosphorus ligands with a mean AARD of 4.67%. Therefore, the proposed model can be employed for successful prediction of solubility of ligands in SC-CO2 medium.

Graphical Abstract

Keywords: Supercritical carbon dioxide; Semi-empirical models; Ligands; Solubility; Modeling

Full paper is available at

DOI: 10.1007/s11696-024-03326-4


Chemical Papers 78 (6) 3525–3544 (2024)

Sunday, June 16, 2024

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