Preparation and study of solid waste oxide/carbon composite catalysts for methyl orange oxidative degradation

The composite catalytic material was synthesized via high-temperature calcination, employing solid waste manganese residue and paper sludge as the primary raw materials. Then, the composition and structure of the material were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Thereafter, the catalytic removal mechanism and efficiency of persulfate (PDS) on methyl orange (MO) in aqueous solutions were systematically investigated. The results demonstrate that the optimal catalytic degradation performance is achieved when the composite ratio of manganese slag to papermaking sludge is 1:1, the roasting temperature is 800°C, and the calcination duration is 1 hour. The degradation rate of methyl orange solution reached 98.15% after 60 minutes under the following conditions: an initial concentration of 20 mg·L−1, a PDS concentration of 1 mmol·L−1, a dosage concentration of MS-PS@800 of 0.6 g·L−1, and an initial pH value of 8.0. The results of radical quenching and electron paramagnetic resonance (EPR) analysis demonstrated that the primary reactive species in the system were superoxide radicals (O2∙−) and sulfate radicals (SO4·−). In summary, the catalyst prepared from double solid waste in this study not only realizes the reuse of resources, but also provides technical support for the treatment method of degrading printing and dyeing wastewater.