Adsorption and desorption kinetics in ZrO₂ - TiO₂ by photoacoustic techniques

Abstract
In this paper we report on the photoacoustic (PA) characterization of ZrO₂-TiO₂ ceramic wafers as a sensing element for solvent adulteration evaluation. The experiments consisted of photoacoustic time dependent monitoring of the sorption and desorption of a droplet of a solvent deposited on the outer face of a ceramic wafer. The used solvents were isopropanol and chloroform. For the polar isopropanol molecule the results shown diffusion into the sample, with a characteristic diffusion time , accompanied by the evaporation at a rate with a time constant . Indeed, for the non polar chloroform, wetting-drying kinetics is adequately described by a simple diffusion-evaporation.