Noncontact and Noninvasive Monitoring of Gas Diffusion from Aqueous Solution to Aprotic Solvent Using the Optical Beam Deflection Method

Abstract

The optical beam deflection method has been applied to noncontact and noninvasive monitoring and analyzing of gas diffusion process from an aqueous solution into an aprotic solvent. Oxygen and carbon dioxide, which are in situ generated by chemical reactions in aqueous solutions above aprotic solvents, have been used as model gases. Both the model gas and the reaction heat diffuse from the aqueous solution to the aprotic solvent and thus generate a concentration gradient and a temperature gradient. Both the concentration gradient and the temperature gradient induce optical beam deflections. Since the thermal diffusion is faster than the mass diffusion, the reaction heat-induced beam deflection signal appears earlier than the concentration gradient-induced one. A simple diffusion model has been used for analyzing the diffusion process. The diffusion coefficient of the model gas in the aprotic solvent can be estimated simply from the beam deflection signal. The diffusion coefficients of O2 in CCl4, CH2Cl2, ...