Catalytic performance of α-MnO2 nanorods on the degradation of rhodamine B using chlorine dioxide as an oxidant

Abstract

Manganese dioxide (MnO₂) nanorods were synthesized by a hydrothermal method using manganese sulfate and sodium hypochlorite as raw materials. Manganese dioxide nanorods were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The as-synthesized MnO₂ nanorods were applied to degrade rhodamine B dyes with high concentration in the presence of chlorine dioxide. The catalytic activity was the highest for manganese dioxide nanorods with rod-shaped morphology, a diameter of 80–100 nm, a length of 1.0–1.5 µm, and a crystal phase of tetragonal α-MnO₂, prepared at 150 °C for a reaction time of 10 h. Under the reaction conditions of a chlorine dioxide concentration of 7.5 mg L⁻¹, a rhodamine B concentration of 50 mg L⁻¹, a reaction time of 30 min, catalyst amounts of 0.60 g L⁻¹ and a pH range of 4–8, the degradation efficiency of rhodamine B approached 99.2%.