Photocatalytic Degradation of Rhodamine B using MnO2 and ZnO Nanoparticles

The oxide semiconductor with different bandgap energy i.e. manganese dioxide (MnO2) (E-g: 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 MnO2 nanoparticles were synthesized by hydrothermal method (160 degrees C, 4 h) using analytical grade manganese sulfate hydrate and potassium permanganate (VII) as precursors. The XRD analysis reveals that the nanoparticles were delta-MnO2. 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 delta-MnO2 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.