MEASUREMENT OF RATE AND EQUILIBRIUM PARAMETERS FOR PHYSICOCHEMICAL PROCESSES PERTAINING TO THE ATMOSPHERE BY GAS-CHROMATOGRAPHY

Laboratory kinetic experiments can be performed under conditions of co ncentration, temperature, pressure, humidity, and so on very close to those prevailing in the atmosphere and in the presence of heterogeneou s sinks by the reversed-flow gas chromatography (RF-GC) technique. It is an absolute rate constant technique, but the system is neither a st atic nor a flow one. It is a diffusion controlled system by means of w hich rate constants and reaction orders with respect to time n(t) of u nimolecular and bimolecular chemical reactions of atmospheric species with other substances can be measured. In the presence of heterogeneou s sinks, the following physicochemical parameters are determined under unsteady-state conditions: the local adsorption parameter k(1) of the analyte A under study and the experimental isotherm, the desorption r ate constant of A from the solid surface k(-1), the rate constant k(2) of a possible first-order or pseudo-first-order surface reaction of t he adsorbed analyte, and the deposition velocity V-d and the reaction probability gamma of A on the heterogeneous sink. (C) 1998 John Wiley & Sons, Inc.