Study of the mechanism of the interaction of vinyl chloride with water by reversed-flow gas chromatography

Abstract

The investigation of the mechanism for the interaction of vinyl chloride (VC) with liquid foods is of great significance in food science. In the present work the model system VC–water was studied by using the relatively new technique of reversed-flow gas chromatography. Using suitable mathematical analysis the following physicochemical quantities were determined: (a) diffusion coefficients of VC into water, (b) overall mass transfer coefficients of VC in the water, and in the carrier gas nitrogen, (c) partition coefficients of VC between water and nitrogen, and (d) constants of Henry’s law for the adsorption of VC by water. From the variation of the above parameters with temperature, and the stirring rate of the water, useful conclusions concerning the mechanism for the VC–water interaction were extracted. The experimental results for the transfer of VC into the bulk water suggest (i) a mechanism consisted of a fast equilibrium step between the VC in the gas phase and in the interface, followed by a slow adsorption of VC into the bulk of water, which is the rate-determining step, when the water is quiescent, and (ii) a mechanism consisted of a slow diffusion of VC from the gas phase to the interface, which is the rate-determining step, followed by a fast equilibrium step between the VC in the interface and in the water bulk, when the water is stirred.