Surface Reaction Rate and Probability of Ozone and Alpha-Terpineol on Glass, Polyvinyl Chloride, and Latex Paint Surfaces

Ozone can react homogeneously with unsaturated organic compounds in buildings to generate undesirable products. However, these reactions can also occur on indoor surfaces, especially for low-volatility organics. Conversion rates of ozone with a-terpineol, a representative low-volatility compound, were quantified on surfaces that mimic indoor substrates. Rates were measured for a-terpineol adsorbed to beads of glass, polyvinylchloride (PVC), and dry latex paint, in a plug flow reactor. A newly defined second-order surface reaction rate coefficient, k(2), was derived from the flow reactor model. The value of k(2) ranged from 0.68 x 10(-14) cm(4)s(-1) molecule(-1) for a-terpineol adsorbed to PVC to 3.17 x 10(-14) cm(4)s(-1) molecule(-1) for glass, but was insensitive to relative humidity. Further, k2 is only weakly influenced by the adsorbed mass but instead appears to be more strongly related to the interfacial activity a-terpineol. The minimum reaction probability ranged from 3.79 x 10(-6) for glass at 20% RH to 6.75 x 10(-5) for PVC at 50% RH. The combination of high equilibrium surface coverage and high reactivity for a-terpineol suggests that surface conversion rates are fast enough to compete with or even overwhelm other removal mechanisms in buildings such as gas-phase conversion and air exchange.