Non-thermal plasma synthesis of sea-urchin like alpha-FeOOH for the catalytic oxidation of Orange II in aqueous solution

In this study, a template-free synthesis of iron oxyhydroxide nanostructures by gliding arc plasma at atmospheric pressure was evaluated. The results showed that exposure of a Mohr’s salt solution to the plasma discharge induces a rapid oxidation–precipitation of iron(II) into a non-porous and amorphous iron(III) (hydr) oxide. After ageing in temporal post-discharge for three hours, the amorphous iron (hydr) oxide was transformed into crystalline goethite (α-FeOOH). The presence of goethite was confirmed by FTIR, Raman spectroscopy and thermogravimetric analysis. Textural analyses showed that the material is mesoporous with a BET surface area of 134 m2 g−1. SEM pictures revealed that the plasma-synthesized goethite particles consist of sea-urchin like hollow spheres. The catalytic activity of such goethite in the Fenton degradation of Orange II (organic dye) showed that this material can be used as heterogeneous catalyst for effective removal of organic pollutants from wastewater. This study establishes that the plasma discharge of gliding arc type can be used as a green and cheap efficient route for the synthesis of porous metal oxide nanostructures.