摘要
In this research,a lucunary Keggin structure,[PMo_2W_9O_（39）]^（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,K_7[PMo_2W_9O_（39）]？ 19H_2O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H_2O_2,pH and reaction time were investigated and optimized. Results show that K_7[PMo_2W_9O_（39）]？ 19H_2O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H_2O_2 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 H_2O_2 was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H_2O_2 and optimize conditions（0.6 g/L of K_7[PMo_（2-） W_9O_（39）H_9H_2O,0.08 mol/L hydrogen peroxide and room temperature）.
In this research,a lucunary Keggin structure,[PMo_2W_9O_（39）]^（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,K_7[PMo_2W_9O_（39）]？ 19H_2O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H_2O_2,pH and reaction time were investigated and optimized. Results show that K_7[PMo_2W_9O_（39）]？ 19H_2O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H_2O_2 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 H_2O_2 was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H_2O_2 and optimize conditions（0.6 g/L of K_7[PMo_（2-） W_9O_（39）H_9H_2O,0.08 mol/L hydrogen peroxide and room temperature）.
基金
Supported by the Islamic Azad University Yazd Branch
