Photocatalytic Degradation of Rhodamine B using MnO_2 and ZnO Nanoparticles

摘要

The oxide semiconductor with different bandgap energy i.e. manganese dioxide (MnO_2) (Eg: 1.30eV) and zinc oxide (ZnO) (E_g: 3.37 eV) nanoparticles were used to degrade Rhodamine B (RhB) under irradiation of UV light (254 nm).The MnO_2 nanoparticles were synthesized by hydrothermal method (160 °C, 4 h) using analytical grade manganese sulfate hydrate and potassium permanganate (VII) as precursors. The XRD analysis reveals that the nanoparticles were δ-MnO_2. The photocatalytic study shows that degradation of RhB solution by ZnO nanoparticles (rate constant: 0.02749 min~(-1)) was approximately four times faster than the δ-MnO_2 nanoparticles (rate constant: 0.0067 min~(-1)). This observation could be attributed to the higher reducing and oxidizing power of ZnO in producing free radicals for photodegradation of RhB solution.