Degradation and Mechanism of Methyl Orange by Nanometallic Particles under a Fenton-Like Process

In this research work, the degradation of methyl orange (MO) in an aqueous solution by nanometallic particles (NMPs) under a Fenton-like process was studied. NMPs were recovered from the fine fraction of automobile shredder residue. Scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were utilized to illustrate the recovered NMPs. Effects of NMP dosage, initial solution pH, initial concentration of MO, and amount of hydrogen peroxide (H₂O₂) in the MO degradation process were studied. Results of this study represent that MO degradation rate was increased with an increase in dosages of NMPs and concentration of H₂O₂ up to a certain limit. However, the degradation rate decreased with an increase in the pH. An acidic pH of the solution was highly favorable for MO degradation under the Fenton-like process. Pseudo-first-order kinetics was well fitted in comparison to pseudo-second-order kinetics for the degradation of MO by NMPs. The value of the pseudo-first-order reaction rate constant (k₁) was increased with an increase in the NMPs and H₂O₂ dosages. In contrast, values of k₁ were decreased with an increase in the pH value and the initial concentration of MO. In contrast, the values of k₂ were decreased with an increase in the doses of NMPs, pH values, and initial concentration of MO, but increased with increasing concentration of H₂O₂. The mechanism of MO degradation by NMPs was the oxidation of MO by hydroxyl radicals, which were generated during the reaction. Degradation of MO by NMPs at pH 2.0 and 3.0 under the Fenton-like process was extremely effective.