Dry deposition of ozone on building materials. Chamber measurements and modelling of the time-dependent deposition

Abstract

Tests of the dry deposition of ozone to the surfaces of a concrete floor tile and an activated carbon cloth (ACC) sample were performed in a deposition chamber. The time-dependent deposition of ozone to the material surfaces was modelled with an adsorption, desorption, reaction model. This made it possible to find deposition velocities at equilibrium, at t=∞, from shorter time runs of 48 h. The total equilibrium deposition velocity on the concrete floor tile was found to decrease from 0.08(10) to 0.057(10) cm s −1 in three consecutive runs on the same sample, and was found to be 0.137(8) cm s −1 on an ACC. All at a linear airflow velocity of 0.092 cm s −1, RH=50% and T=22°C. Varying the airflow in the deposition chamber, the surface deposition velocity was found to equal to the total deposition velocity for the concrete floor tile. A surface deposition velocity of 0.186(8) cm s −1 was found for the ACC sample. The total real area and the reaction rate constant for the decomposition of ozone was found to be larger, and the adsorption rate constant, the desorption rate constant and the mass of ozone on the surface smaller, on the ACC sample than on the concrete floor tile.