Optimization of photo-electro/Persulfate/nZVI process on 2 –4 Dichlorophenoxyacetic acid degradation via central composite design: a novel combination of advanced oxidation process

Abstract2 –4 Dichlorophenoxy acetic acid is most publicly applied from chlorinated phenoxy acids herbicides. In this research, central composite design for optimization of photo-Elecro/persulfate/nZVI process to degradation and mineralization of this herbicide in aqueous solution to environment protection w as applied. The initial pH (2–4), persulfate anion concentration (0.25–0.5 mg/L), direct electrical (0.5–1 A), herbicide concentration (50–100 mg/l), nZVI dose (0.05–1 mg/L), and reaction time (50–100 mg/l) are independent variables optimized. Also, the synergist effect, COD and TOC removal, the effect of radical scavengers, and by-products were investigated. The fitting of the model, suggested a quadratic model (R2 = 0.9926). F-value andP value of ANOVA were 719.81 and 0.0001 respectivelty. After optimizing the PEP/nZVI process, the proposed optimal conditions was pH  = 3.4, persulfate concentration equal to 0.49 mg/l, in 1 A direct current, nZVI dose equal to 0.1 mg/l, in 50.05 mg/l herbicide concentration as an initial concentration, in 80 min reaction time. The theoretical and actual removal was evaluated 91.99% and 92%, respectively. In the optimum c ondition, 45.4% synergist effect indicated. 78.3% and 66.5% of initial COD and TOC were decreased. 39.02% of Cl ion was released form 2,4-D structure. The presence of radical scavengers have an adverse impact on the performance of process. The highest amount of radical scavenging was in metha...
Source: Journal of Environmental Health Science and Engineering - Category: Environmental Health Source Type: research