NONCONTACT AND NONINVASIVE MONITORING OF GAS-DIFFUSION FROM AQUEOUS-SOLUTION TO APROTIC-SOLVENT USING THE OPTICAL BEAM DEFLECTION METHOD

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, w hich 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 apr otic solvent and thus generate a concentration gradient and a temperat ure gradient. Both the concentration gradient and the temperature grad ient induce optical beam deflections. Since the thermal diffusion is f aster than the mass diffusion, the reaction heat-induced beam deflecti on signal appears earlier than the concentration gradient-induced one. A simple diffusion model has been used for analyzing the diffusion pr ocess. The diffusion coefficient of the model gas in the aprotic solve nt can be estimated simply from the beam deflection signal. The diffus ion coefficients of O-2 in CCl4, CH2Cl2, C2H4Cl2, and CS2 have been ob tained. The method is expected to be particularly useful for those dif fusion processes where other methods are not applicable.