Kinetic model of degradation of 2,4-dichlorophenoxyacetic acid in aqueous solution using ultrasound-enhanced ozonation

The degradation of chlorinated phenoxy acetic acids herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) in aqueous solution using ultrasound-enhanced ozonation was studied in this paper. The effect of different parameters such as pH value and 2,4-D initial concentration in reaction solution on the kinetics of degradation of 2,4-D was investigated in an experimental reactor. It is found that the degradation of 2,4-D by ultrasound-enhanced ozonation follows a pseudo-first-order kinetic. The pseudo-first-order rate constants vary with pH value and 2,4-D initial concentration in solution. Under the fixed reaction temperature, gas flow rate and ultrasound frequency, a kinetic model is proposed to predict overall 2,4-D degradation using O₃/US for different pH values and 2,4-D initial concentrations. The simulation data using the proposed model are compared with the experimental data. It is shown that the data calculated from proposed model agree well with the experiment. The model proposed in this paper is simple and useful in practical applications. The experimental results demonstrate that the model is able to successfully describe the reaction.