Exponential saturator: A novel gas-liquid partitioning technique for measurement of large limiting activity coefficients

A method has been developed for the accurate determination of large Limiting activity coefficients, based on a novel gas-liquid partitioning measurement principle described in this work. This technique is similar to that of inert gas stripping, but contrary to stripping, it deals with the reverse process, i.e., with saturation. The method, denoted by us as the exponential saturator, consists of measuring the rate of solvent saturation by the solute when an inert gas presaturated with the solute vapor is being passed through the solvent in the equilibrium cell. The process of solvent saturation is monitored by periodic analysis of the outlet gas by gas chromatography. In this work, an especially convenient application of the exponential saturator for the determination of the Limiting activity coefficients of hydrophobic solutes in water is presented. Good performance of the developed method is verified by reproducibility tests and by the agreement with measurements by other methods. Limiting activity coefficients, Henry's law constants, and gas-liquid partition coefficients measured by the new method are reported for 16 aromatic, halocarbon, and oxygenated solutes of industrial and environmental interest in water at ambient temperatures.