Solubility of H2S in (H2O + piperazine) and in (H2O + MDEA + piperazine)

New experimental results for the solubility of hydrogen sulfide in aqueous solutions of piperazine are presented for piperazine molalities up to 4 mol/kg of water, temperatures between 313 and 393 K, and pressures up to about 9 MPa. Furthermore, the solubility of hydrogen sulfide was measured in about 2 m MDEA + 2 m piperazine aqueous solutions at 353 K up to about 6 MPa. Considering the new experimental data, a thermodynamic model for describing phase equilibria for the system H2S–methyldiethanolamine–water has been extended allowing for the presence of piperazine.