A comprehensive modeling investigation of hydrogen sulfide absorption by Deep Eutectic Solvents

Natural gas is a valuable source of energy, however, it also contains hazardous compounds, such as hydrogen sulfide (H₂S) acid gas, which needs to be eliminated to make it safe for use. If H₂S is released, it can cause serious hazards like environmental issues and human respiratory or even death. Up to now, amine-based solvents have been used for gas sweetening. However, they are not environmentally friendly solvents, so replacing them with green solvents is required. Deep Eutectic Solvents (DESs) are the high-potential candidates of green solvents for this purpose. This study investigated comprehensive thermodynamic modeling of H₂S solubilities in a wide range of different nature DESs using two thermodynamic approaches of φ-φ and γ-φ and one chemical absorption approach. The largest and most updated H₂S solubility in DESs’ data bank was gathered from open literature including 338 data points for 33 different DESs over a wide range of temperature and pressure. For the investigated approaches, the SRK-SRK, SRK-NRTL, and RETM (1:2) models with the AARD% values of 13.42, 11.64, and 11.21, respectively led to the best results. According to comprehensive investigation and data analysis, general guidelines for using different thermodynamic models for H₂S solubility in DESs were proposed.