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

摘要

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 (resor-cinol) 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.