Document Type : Research Paper


Assistant Professor, Faculty of Chemical and Materials Engineering, Shahrood University of Technology, Shahrood, Iran.


In current work, perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state (EoS) together with the reaction equilibrium thermodynamic model (RETM) was employed to correlate H2S solubility in three carboxylate ionic liquids including [emim][Ace], [bmim][Ace], and [hmim][Ace]. The RETM proposes a chemical reaction approach between ionic liquid (IL) (B) and H2S (A) in the liquid phase. Moreover, PC-SAFT EoS contributes to VLE calculations. All the H2S and the investigated ILs, as self-associating components, are assumed to follow the 2B association scheme. Five adjustable variables of PC-SAFT EoS for pure components were calculated using experimental data of liquid density and vapor pressure. Afterward, the binary systems were investigated by applying RETM. Indeed, two nested loops calculate the liquid phase, total pressure, and vapor phase concentrations, respectively. For these systems, an AAD% of 2.29%, 3.09%, and 7.65% was obtained for H2S–[emim][Ace], H2S–[bmim][Ace], and H2S–[hmim][Ace] systems, respectively.


  • Pure [emim][Ace], [bmim][Ace], and [hmim][Ace] were modeled;
  • H2S solubility in three carboxylates ionic liquids was correlated using PC-SAFT EoSs;
  • RETM was applied to calculate the liquid-phase concentrations;
  • RETM–PCSAFT presents AADs% equal to 2.29%, 3.09%, and 7.65% for H2S–[emim][Ace], H2S–[bmim][Ace], and H2S–[hmim][Ace] systems respectively;
  • The results of RETM–PCSAFT were compared with those of RETM–CPA.


Main Subjects

Afsharpour, A., Application of Reaction Equilibrium Thermodynamic Model for Correlation of H2S Solubility in Ionic Liquids [Emim][Ace] and [Hmim][Ace] Using CPA Equation of State, Petroleum Science, and Technology, Vol.37, No.14, p.1648–1654, Doi:10.1080/10916466.2019.1602633, 2019.
Afsharpour, A., A New Approach for Correlating of H2S Solubility in [Emim][Lac], [Bmim][Ac] and [Emim][Pro] Ionic Liquids Using Two-parts Combined Models, Chinese Journal of Chemical Engineering, Doi:Https://Doi.Org/10.1016/J.Cjche.2020.11.046, 2021a.
Afsharpour, A., An RETM Approach to Model CO2 and H2S Solubility in Four Protic Ionic Liquids Using MSRK and CPA EOSS., Journal of Molecular Liquids, 3Vol.24, 114684 P.,Doi:Https://Doi.Org/10.1016/J.Molliq.2020.114684,2021b.
Afsharpour, A., and Haghtalab, A., Modeling CO2 Solubility in Aqueous N-Methyl diethanolamine Solution Using Electrolyte Modified HKM Plus Association Equation of State, Fluid Phase Equilibria, Vol.433, p.149–158, Doi:Https://Doi.Org/10.1016/J.Fluid.2016.10.029,2017a.
Afsharpour, A., and Haghtalab, A., Simultaneous Measurement Absorption of CO2 and H2S Mixture into Aqueous Solutions Containing Diisopropanolamine Blended with 1-Butyl-3-Methylimidazolium Acetate Ionic Liquid, International Journal of Greenhouse Gas Control, Vol.58, p.71–80. Doi:Https://Doi.Org/10.1016/J.Ijggc.2017.01.004, 2017b.
Gross, J., and Sadowski, G. Perturbed-chain SAFT:  An Equation of State based on a Perturbation Theory For Chain Molecules, Industrial & Engineering Chemistry Research, Vol.40, No.4, p.1244–1260, Doi:10.1021/Ie0003887, 2001.
Haghtalab, A., and Afsharpour, A., Solubility of CO2+H2S Gas Mixture into Different Aqueous N-Methyldiethanolamine Solutions blended with 1-Butyl-3-Methylimidazolium Acetate Ionic Liquid. Fluid Phase Equilibria, Vol.406, p.10–20, Doi:Https://Doi.Org/10.1016/J.Fluid.2015.08.001, 2015.
Haghtalab, A., and Kheiri, A., High-Pressure Measurement and CPA Equation of State for Solubility of Carbon Dioxide and Hydrogen Sulfide in 1-Butyl-3-Methylimidazolium Acetate, The Journal of Chemical Thermodynamics, 89, p.41–50. Doi:Https://Doi.Org/10.1016/J.Jct.2015.04.032, 2015.
Hamzehie, M. E., Fattahi, M., Najibi, H., Van Der Bruggen, B., and Mazinani, S., Application of Artificial Neural Networks for Estimation of Solubility of Acid Gases (H2S and CO2) in 32 Commonly Ionic Liquid and Amine Solutions. Journal of Natural Gas Science and Engineering, 24, p.106–114, Doi:Https://Doi.Org/10.1016/J.Jngse.2015.03.014, 2015.
Huang, K., Cai, D.-N., Chen, Y.-L., Wu, Y.-T., Hu, X.-B., and Zhang, Z.-B. Thermodynamic Validation of 1-Alkyl-3-Methylimidazolium Carboxylates as Task-Specific Ionic Liquids for H2S Absorption, AICHE Journal, Vol.59, No.6, p.2227–2235, Doi:Https://Doi.Org/10.1002/Aic.13976,2013.
Ma, X.-X., Wei, J., Zhang, Q.-B., Tian, F., Feng, Y.-Y., and Guan, W., Prediction of Thermophysical Properties of Acetate-based Ionic Liquids Using Semiempirical Methods, Industrial & Engineering Chemistry Research, Vol.52, No.27, p.9490–9496, Doi:10.1021/Ie401130d,2013.
Macías-Salinas, R., Chávez-Velasco, J. A., Aquino-Olivos, M. A., Mendoza De La Cruz, J. L., and Sánchez-Ochoa, J. C., Accurate Modeling of CO2 Solubility in Ionic Liquids Using A Cubic Eos. Industrial & Engineering Chemistry Research, Vol.52, No.22, p.7593–7601, Doi: 10.1021/Ie400106g, 2013.
Rahmati-Rostami, M., Behzadi, B., and Ghotbi, C., Thermodynamic Modeling of Hydrogen Sulfide Solubility in Ionic Liquids Using Modified SAFT-VR and PC-SAFT Equations of State, Fluid Phase Equilibria, Vol.309, No.2, p.179–189, Doi:Https://Doi.Org/10.1016/J.Fluid.2011.07.013, 2011.
Senol, I., Ilke Senol Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT) Parameters for Propane, Ethylene, and Hydrogen Under Supercritical Conditions,2011.
Shojaeian, A., Thermodynamic Modeling of Solubility of Hydrogen Sulfide in Ionic Liquids Using Peng Robinson-two State Equation of State, Journal of Molecular Liquids, Vol.229, p.591–598, Doi:Https://Doi.Org/10.1016/J.Molliq.2016.12.001,2017.
Soltani Panah, H., Modeling H2S and CO2 Solubility in Ionic Liquids Using The CPA Equation of State Through A New Approach. Fluid Phase Equilibria, 437, p.155–165, Doi:Https://Doi.Org/10.1016/J.Fluid.2017.01.023, 2017.