Using Fe/Ag nanostructures covered by Zn for the degradation of 2, 4 dichlorophenoxyacetic acid assisting with light irradiation and ozonation; optimisation and kinetic studies

Abstract

ABSTRACT A nanostructure comprising Fe/Ag covered by ZnO was fabricated using a facile chemical method based on the degradation of 2,4-D using an ozonation system under the irradiation of UV/Visible light generated from an LED source. The Fe/Ag covered by ZnO was characterised using XRD, SEM and FTIR. The degradation of 2,4-D was studied as a function of variables pH, initial 2,4-D concentration, dose of catalyst and the time of irradiation by developing a quadratic model derived from central composite design (CCD). An independent kinetic study was then established under the basis of the optimised values of the independent factors obtained from CCD model. The optimised values of pH, 2,4-D initial concentration, dose of catalyst and time of irradiation were 5, 62 mgL−1, 0.078 gL−1 and 63 min, respectively. ANOVA results of the quadratic model showed the adjusted R 2 of 0.97% and the value of 0.55 for the Lack of Fit (LoF). According to the kinetic study, the pseudo second model reveals a good fit on the experimental results (R 2 = 0.98). Maximum removal of 80% was obtained in the optimum condition and in the presence of ozone. Considering the safety and technical restrictions of applying UV light as an activator agent in full scale treatment systems, it seems that the use of LED in the degradation systems acquires promising results in terms of pesticides degradation.