Highly efficient degradation of rhodamine B by α-MnO2 nanorods

Manganese dioxide (α-MnO2) nanorods with diameters of about 5–15 nm and lengths of 100–150 nm were synthesized by a simple co-precipitation method, and the degradation mechanism of rhodamine B (RhB) at different pH levels was investigated. The α-MnO2 nanorods exhibited a high efficiency and rapid removal rate of RhB, which reached about 97.5% within 10 min when pH = 4 (and pH = 6.6) and 97.7% within 50 min when pH = 9 in the presence of H2O2. The results also indicated that a lower pH value is conducive to the blue shift of the characteristic peak of RhB dye and the attenuation of the characteristic peak intensity, which is mainly attributed to the combined effect of oxidative degradation and adsorption decolourization when pH is less than 9. Moreover, the α-MnO2 nanorod exhibits an excellent recyclability and catalytic stability. This research indicates that α-MnO2 nanorods have a potential application in practical dye pollutant treatment.