DEPOSITION PARAMETERS OF AIR-POLLUTANTS ON SOLID-SURFACES, MEASURED IN THE PRESENCE OF SURFACE AND GASEOUS REACTIONS, WITH A SIMULTANEOUS DETERMINATION OF THE EXPERIMENTAL ISOTHERMS

A method is described for measuring deposition velocities and reaction probabilities of air pollutants with solid surfaces, in the presence of a chemical reaction between two pollutants in the gas phase above t he solid. The theoretical analysis is based on experimental adsorption isotherms measured simultaneously through the local adsorption parame ters, together with the rate constants for desorption, first-order sur face reaction and gaseous chemical reactions. The experimental procedu re is that of the reversed-flow gas chromatography (RF-GC) technique, the analysis of the diffusion bands being effected by a personal compu ter programme. The methodology has been applied to the action of gaseo us hydrocarbons on two metal oxides, and of dimethyl sulfide on Pentel i marble particles and on pieces obtained from three archaeological st atues. All physicochemical parameters mentioned above were measured bo th in the absence and in the presence of a second gaseous pollutant (N O2). The synergistic effects in the gas phase on the Various depositio n parameters was fairly obvious. (C) 1997 Elsevier Science B.V.