AQUEOUS DEGRADATION OF VOCs IN THE OZONE COMBINED WITH HYDROGEN PEROXIDE OR UV RADIATION PROCESSES. 2. KINETIC MODELING

摘要

A kinetic model for the removal of trichloroethylene and trichloroethane from natural waters with ozonation processes has been proposed and tested at different conditions implying the presence of hydrogen peroxide or UV radiation. The model is constituted by the mol balance equations of the organochlorine compound, ozone (both in water and gas phases) and hydrogen peroxide and predicts the concentration of these substances with reaction time at different conditions. Main variables that affect the oxidation rate are gas flow rte (volumetric mass transfer and volatility coefficients), concentration of hydrogen peroxide and intensity of UV radiation. The kinetic model predicts reasonably well experimental concentrations of TCA during the ozonation at low gas flow rate (thus minimizing the importance of volatility) but overestimates the experimental concentrations when UV radiation or hydrogen peroxide are simulataneously applied to the ozonation of TCE, specially at 20 Lh~-1 gas flow rate. The presence of natural substances different of carbonates can be the reason of these deviations because of their hydroxyl free radical scavenging potential character not accounted for in the kinetic model.