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

[Display omitted] •The purity of as-prepared MgO2 nanoparticles reaches more than 94 wt%.•The degradation reaction can be conducted in a wide pH range at room temperature.•Hydroxyl radicals are detected in the MgO2/Fe3+ degradation system.•Highly pure MgO2 is an ideal substitute for H2O2 in Fenton/Fenton-like reactions. 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.