A reaction kinetic model for 2, 4-D decomposition in aqueous media including direct photolysis, direct ozonation, UVC and pH enhancement

MARÍA B. GILLIARD; CARLOS A. MARTÍN; ALBERTO E. CASSANO; MARÍA E. LOVATO

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 52 p. 14034 - 14048

0888-5885

This report presents a comprehensive study of the degradation kinetics of herbicide 2,4-D using ozone with and without intensification with UVC radiation. The by-products cause several seriesparallel reactions that compete with the process of photon absorption when radiation is applied.Five processes were analyzed separately: (i) the direct photolysis of 2,4-D and its main byproducts, (ii) direct ozonation in the absence of hydroxyl radicals using tert-butanol as radical scavenger, (iii) the oxidation when ozone reacts in parallel with hydroxyl radicals, (iv) the reaction enhanced with UVC radiation and (v) the oxidation improved by pH modifications.A kinetic model was developed based on the main reaction by-products. The corresponding parameters of the reacting system were determined (9 of its 29 kinetic constants were previously unknown).Simulation results, including a rigorous description of the reacting system and the radiation field (having dark and illuminated volumes) agree very well with the experimental data.