Preparation of Ultrasmall Goethite Nanorods and Their Application as Heterogeneous Fenton Reaction Catalysts in the Degradation of Azo Dyes

The discharge of azo dyes causes great harm to humans and the environment. Azo dyes can be degraded by a heterogeneous Fenton reaction catalyzed by α-FeOOH nanorods. However, because of the large size of conventional goethite nanorods, the reaction rate of the heterogeneous Fenton reaction is limited. In this study, we proposed a template method strategy for synthesizing ultrasmall α-FeOOH nanorods (SFNs) and investigated their use for catalyzing the degradation of an azo dye, methyl orange (MO). Transmission electron microscopy results suggested that the sizes of SFNs are much smaller than those of conventional nanorods (LFNs), and the catalytic efficiency of SFNs is 7.4 times higher than that of LFNs. This can be explained by the higher specific surface area and more catalytic sites of the catalyst. The degradation rate of MO increases with an increase in the concentrations of hydrogen peroxide (H2O2) and SFNs. Moreover, the MO degradation rate can reach 98% under the appropriate parameters after 60 min of reaction. In addition, reuse experimental results suggest that SFNs manufactured using our proposed approach achieved satisfied reusability, indicating that SFNs have potential application prospects in the degradation of azo dyes by catalyzing the heterogeneous Fenton reaction.