Reaction Kinetic Model for 2,4-Dichlorophenoxyacetic Acid Decomposition in Aqueous Media Including Direct Photolysis, Direct Ozonation, Ultraviolet C, and pH Enhancement

Abstract

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.

Degradation of 2,4-dichlorophenoxyacetic acid by photolysis and photo-Fenton oxidation

“…This behavior could be explained by the absorbance spectrum of the molecule, which exhibited maxima at 201, 230 and 283 nm and by the differences in lamp irradiation intensity in this wavelength range. In the best conditions, 2,4-D was totally degraded by direct photolysis in 10 min and total mineralization was achieved in 1 h. The results obtained with the LP Hg lamp (using quartz immersion well) were consistent with those reported by other authors [16,[24][25][26][27] in similar conditions.…”

“…Several publications have studied the degradation of 2,4-D in water by different AOPs, mainly: heterogeneous photocatalysis over TiO 2 , Ca-Ce-W-TiO 2 , Au/TiO 2 -CeO 2 [9][10][11][12], electrochemical-based treatment [13][14][15], ozonation [16][17][18][19][20] − alone, or combined with UV [16], heterogeneous catalysts [17][18][19] or hydrogen peroxide [20]. Most of these works, reported total degradation of the pollutant and above 40% mineralization yield in 15 min of reaction time.…”

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4D) on sargassum activated carbon

“…It is for all of the above, that studies for the decontamination of waters contaminated with 2,4-D have been prioritized at the international level. Among the most studied processes are the advanced oxidation processes [8][9][10][11][12][13][14][15][16][17] and adsorption [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] .…”

Supervised Machine Learning Algorithms for Predicting Rate Constants of Ozone Reaction with Micropollutants

“…To harness the ozone reaction with micropollutants and assess its removal efficiency, accurate determination of the associated second-order rate constant is of significant importance. , Actually, in recent years, both experimental and theoretical approaches have been performed to determine the rate constants for the degradation of micropollutants in an aquatic environment. − By comparison, experimental determination is in general costly and time-consuming, but the results are more accurate. − However, assessing the rate constants toward the gradually increased number of emerging micropollutants is a nontrivial task by experimentation, and model-based prediction becomes an appropriate alternative. In this regard, the QSPR method based on the concept that the molecular properties/activities are determined by their structures has been gaining popularity .…”