Highly pure MgO₂ nanoparticles as robust solid oxidant for enhanced Fenton-like degradation of organic contaminants

In typical Fenton/Fenton-like reactions, H₂O₂ was usually used as an oxidant to degrade organic contaminants. However, liquid H₂O₂ is unstable, easy to decompose and has high biological toxicity especially at high concentration. Herein, highly pure magnesium peroxide (MgO₂) nanoparticles were first synthesized and used instead of H₂O₂ to degrade organic dyes. The structure and morphology of as-prepared products were confirmed by XRD, SEM, TEM and FTIR techniques. The active oxygen content of MgO₂ nanoparticles reached up to 26.93 wt%, suggesting a high purity of the as-prepared sample. The degradation performance of MgO₂ nanoparticles towards organic contaminants was systematically investigated in the terms of the molar ratio of Fe³⁺ to MgO₂, the dosage of MgO₂, initial solution pH and different organic dyes. The results indicated the as-prepared MgO₂ exhibited excellent degradation ability to various types of organic dyes. 10 mg of MgO₂ nanoparticles could almost completely degrade 200 mL of 20 mg/L methylene blue (MB) in 30 min with a TOC removal rate of 70.2%. The efficient degradation performance was ascribed to the generation of hydroxyl radicals in the MgO₂/Fe³⁺ system. The pathways of MB degradation were also proposed based on the determination of the reaction intermediates.