Solubility of H2S under Haloalkaliphilic Conditions: Experimental Measurement and Modeling with the Electrolyte NRTL Equation

Haloalkaliphilic biological desulfurization has been recognized as a promising technology due to its remarkable economy and good performance. The process removes H2S from gases using aqueous solutions of alkali carbonates. In this study, the solubility of H2S in an aqueous Na2CO3–NaHCO3 solution was first experimentally measured by a static analysis method at an operating pressure and temperature of biological desulfurization. An accurate and comprehensive thermodynamic model was developed based on the electrolyte nonrandom two-liquid model for the solubility of H2S in aqueous solutions of alkali carbonates. The solubility of H2S in pure water is predicted and compared favorably to previous literature, with the temperature varying from 298.16 to 377.45 K and pressure up to 39.6 bar. The average deviation of the model predictions compared to all experimental data is 0.95% for the solubility of H2S in an aqueous Na2CO3–NaHCO3 solution. This study will provide a valuable reference for the process design, simulation, and optimization of haloalkaliphilic biological desulfurization in the future.