Abstract:

The degradation of methylene blue by catalytic oxidation in Na₂WO₄-H₂O₂ system was discussed. The results showed that the degradation rate of methylene blue was near 100% after 40 min of reaction in Na₂WO₄-H₂O₂ system．The optimum conditions for 100mL methylene blue（10 mg/L）degradation were as follows：reaction temperature 60 ℃，sodium tungstate（0.01 mol/L）dosage 7.0 mL，30% H₂O₂ solution dosage 3.5mL. The degradation of methylene blue was effective in a wide range of pH value（1～14）. The UV-Vis spectroscopic analyses found that the characteristic absorption peaks originally in 664 nm，614 nm and 292 nm，244 nm disappeared，indicating that hazardous organic compounds were transformed into small molecules. Under these conditions，reaction rate constant for methylene blue degradation was 0.0879 min^－1，activation energy was 34.61 kJ/mol. The degradation of methylene blue in Na₂WO₄-H₂O₂ system accorded well with the first-order kinetics mode1.