Photodegradation and Box-Behnken design optimization for methomyl using Fenton process based on synthesized CuO nanocrystals via facile wet chemical technique

Abstract

Nanocrystals of copper oxide (n-CuO) were synthesized using a simple cost-efficient wet chemical procedure and characterized via X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The n-CuO produced was used as a reagent of Fenton reaction for the mineralization of carbamate methomyl pesticide in aqueous solution. The system parameters were examined with the objective of optimization using a Box-Behnken design (BBD). A mathematical model of the treatment process was developed, with a good regression coefficient (R2 = 99.7) for a removal efficiency of 99%, with a 15-min reaction time. Analysis of the experimental data suggested that the reaction kinetics were best described by a second-order reaction model. The thermodynamic parameters calculated suggested that the non-spontaneous nature of oxidation at high temperature which was corroborated by positive ΔG’ and negative ΔS’ values. Also, the positive ΔH’ values indicated that the reaction was exothermic. The low activation energy (37.7 kJ/mol) indicated the reaction proceeds at a low energy level.