SOLUBILITY OF ARGON IN MICELLAR AQUEOUS-SOLUTIONS OF SODIUM DODECYL-SULFATE

An apparatus based on the saturation method was used to study the solu bility of argon in aqueous solutions of sodium dodecyl sulfate (8.000, 25.00, 50.00, 75.00, and 100.0 mM) in the temperature range 297.15-32 3.15 K and at atmospheric pressure. The solubility at concentrations a bove the critical micelle concentration was found to increase linearly with the concentration of the added surfactant. Comparisons were made with the solubilities of argon in water and dodecane, suggesting that the interior of the micelles provide a hydrocarbon-like environment f or its dissolution. The solubility of argon in the SDS micelles was fo und to decrease as the temperature increases from 297.15 to 308.15 K a nd then to increase for higher temperatures up to 323.15 K. Calculatio ns of the standard molar Gibbs energy, enthalpy, and entropy changes f or the process of transferring the solute molecules from the gaseous p hase to the micellar solution were also made, in an attempt to find ev idence for possible structural changes. (C) 1995 Academic Press, Inc.