Intensification of volatile organic compounds mass transfer in a compact scrubber using the O 3/H 2O 2 advanced oxidation process: Kinetic study and hydroxyl radical tracking

Abstract

This study assesses the potential of ozonation and advanced oxidation process O 3/H 2O 2 to enhance the dimethyldisulfide (DMDS) mass transfer in a compact chemical scrubber developed for air treatment applications. Theoretical calculations, through Hatta number and enhancement factor evaluations for two parallel irreversible reactions, were compared to experimental data and enabled the description of the mass transfer mechanisms. These calculations required the determination of the kinetic constant of the DMDS oxidation by molecular ozone ( k DMDS / O 3 ) and the measurement of the hydroxyl radical concentration within the scrubber. The competitive kinetic method using the 1,2-dihydroxybenzene (resorcinol) enabled to determine a value of the kinetic constant k DMDS / O 3 of 1.1 × 10 6 M −1 s −1 at 293 K. Then, experiments using para-chlorobenzoic acid in solution allowed measuring the average hydroxyl concentration in the scrubber between the inlet and the outlet depending on the chemical conditions (pH and inlet O 3 and H 2O 2 concentrations). High hydroxyl radical concentrations (10 −8 M) and ratio of the HO°-to-O 3 exposure ( R ct ≈ 10 −4) were put in evidence.