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The solubility of hydrogen sulfide in 2 m(about 0.146 mass fraction) aqueous solutions of 1,4-diazacyclohexane (piperazine, PIPH2) was measured at low gas loadings (at stochiometric molar ratios of hydrogen sulfide to PIPH2between about 0.14 and 1.04) and low partial pressures of hydrogen sulfide (from about (1.3 to 98.7) kPa) at (313.5 and 392.2) K by headspace gas chromatography. The new experimental results are a supplement to previously published data in the high gas-loading region. The new experimental data are compared to prediction results from a thermodynamic model that was based only on gas solubility data in the high gas-loading area. That thermodynamic model for describing the vapor−liquid equilibrium uses Pitzer’s molality-based equation for the excess Gibbs energy of the aqueous solution. The average relative deviation between the new experimental results and the predictions for the partial pressure of hydrogen sulfide amounts to 10 %. [ABSTRACT FROM AUTHOR]

The solubility of carbon dioxide in aqueous mixtures of 2,2′-methyliminodiethanol (N-methyldiethanolamine, MDEA) and 1,4-diazacyclohexane (piperazine, PZ) was measured at low gas loadings (at stoichiometric molar ratios of carbon dioxide to (MDEA PZ) between about 0.02 and 0.83) and consequently low partial pressures of carbon dioxide (from about (0.1 to 150) kPa) at three temperatures (313 K, 353 K, and 393 K) by headspace gas chromatography. The molality of MDEA in the aqueous mixture was varied between (2 and 8) mol·(kg of water)−1and the molality of piperazine was varied between (1 and 4) mol·(kg of water)−1. The new experimental data supplement recently published high-pressure data for the same systems. Comparisons with prediction results from a formerly published thermodynamic model reveal that the set of model parameters from that previous publication should be revised. [ABSTRACT FROM AUTHOR]

A synthetic technique was used to measure the solubility of carbon dioxide in three aqueous solutions of 2,2′-methyliminodiethanol (N-methyldiethanolamine, MDEA) and piperazine (PZ) at around (313, 333, 353, and 393) K and pressures between about (0.2 and 10) MPa. The molalities of (MDEA + PZ) in the aqueous solutions were (2.2 + 1.97), (4.22 + 2.01), and (7.83 + 2.07), respectively. The loading of the amines by carbon dioxide (i.e., the molar ratio of (MDEA + PZ) and CO2varied between 0.2 and 2.0 The new experimental results are to supplement previously published experimental data of our research group for a single solution of both amines {molalities of (MDEA + PZ) in the aqueous solutions: (2.0 + 2.0)}. The new experimental results are compared to predictions from a model that combines previously published models for (CO2+ MDEA + H2O) and (CO2+ PZ + H2O). [ABSTRACT FROM AUTHOR]