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 the solid. The theoretical analysis is based on experimental adsorption isotherms measured simultaneously through the local adsorption parameters, together with the rate constants for desorption, first-order surface reaction and gaseous chemical reactions. The experimental procedure is that of the reversed-flow gas chromatography (RF-GC) technique, the analysis of the diffusion bands being effected by a personal computer programme. The methodology has been applied to the action of gaseous hydrocarbons on two metal oxides, and of dimethyl sulfide on Penteli marble particles and on pieces obtained from three archaeological statues. All physicochemical parameters mentioned above were measured both in the absence and in the presence of a second gaseous pollutant (NO2). The synergistic effects in the gas phase on the Various deposition parameters was fairly obvious. (C) 1997 Elsevier Science B.V.