摘要: In this research, a lucunary Keggin structure,[PMO₂W₉0₃₉]^7- was selected as an efficient homogenous catalyst for degradation of an azo dye (direct blue 71) and a simple method was developed for degradation of DB71. The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates, K₇[PMO₂W₉O₃₉]·19H₂O, as a homogenous catalyst at room temperature. The reaction is monitored spectrophotometrically by measuring the absorbance of dye at λ=585 nm. Some parameters including concentration of catalyst, concentration of H₂O₂, pH and reaction time were investigated and optimized. Results show that K₇[PMO₂W₉O₃₉]·19H₂0 is more efficient in the presence of hydrogen peroxide. Degradation of dye in the presence of the catalyst and H₂O₂ could lead to the disappearance approximately 65% of dye after 60 min. But degradation for the same experiment performed in the absence of catalyst or in the absence of H₂O₂ was 22% or 5% respectively. Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst, H₂O₂ and optimize conditions (0.6 g/L of K₇[PMO₂-W₉O₃₉]·19H₂O, 0.08 mol/L hydrogen peroxide and room temperature).