Efficient degradation of methylene blue dye by catalytic oxidation using the Na8Nb6O19•13H2O/H2O2 system

Na8Nb6O19 center dot 13H(2)O/H2O2 particles were synthesized by a simple hydrothermal method. The catalysts were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and thermogravimetric and differential scanning (TG-DSC). The XRD and TG-DSC analyses indicated that Na8Nb6O19 center dot 13H(2)O/H2O2 was an intermediate hexaniobate during the preparation of NaNbO3 powders. Methylene blue (MB) dye degradation using Na8Nb6O19 center dot 13H(2)O/H2O2 , Nb2O5/H2O2 and NaNbO3/H2O2 systems were investigated, respectively. Among the catalytic oxidation systems, Na8Nb6O19 center dot 13H(2)O/H2O2 showed the highest activity for degradation of MB in the presence of H2O2. The results indicated that the dye degradation efficiency could be 93.5% at 30 degrees C after 60 min in the presence of the Na8Nb6O19 center dot 13H(2)O/H2O2 system. It was also found that the degradation of MB over the catalytic systems followed pseudo-first-order kinetics, and the degradation rate was 0.02376 min(-1) in the Na8Nb6O19 center dot 13H(2)O/H2O2 system, which was higher than that in the Nb2O5/H2O2 and NaNbO3/H2O2 systems. A possible mechanism for MB catalytic oxidation degradation using the Na8Nb6O19 center dot 13H(2)O/H2O2 system was proposed.