A New Thermodynamic Correlation for Apparent Henry’s Law Constants, Infinite Dilution Activity Coefficient and Solubility of Mercaptans in Pure Water

Abstract Mercaptans (RSH) or thiols are odorous substances offensive at low concentration and toxic at higher levels. The presence of mercaptans as pollutants in the environment creates a great threat on water and air safety. In this study, the solubility of mercaptans in water was studied through the use of apparent Henry’s Law constant (H) and infinite dilution activity coefficients (γ∞). These thermodynamic properties are useful for environmental impact studies and engineering design particularly in processes where dilute aqueous systems are involved. The aim of this paper is to develop a new thermodynamic correlation for estimation of apparent Henry’s Law constant (H), infinite dilution activity coefficient (γ∞) and solubility of C1-C4 mercaptans including their isomers in pure water. This correlation was developed based on compiled literature data. New measurements of apparent Henry’s Law constant and infinite dilution activity coefficients of methyl mercaptan and ethyl mercaptan in water were carried out to validate the developed correlation. Validation with new measurement data showed a good consistency with low differences (less than 5%) for majority of the data. Additionally, heat of absorption of various mercaptans in pure water was discussed based on temperature influence, Henry Law Constants and solubility.