Degradation of organic dye using a new homogeneous Fenton-like system based on hydrogen peroxide and a recyclable Dawson-type heteropolyanion

The main objective of this work was to study the degradation of Acid Orange 7 (AO7) dye in aqueous solution by hydrogen peroxide using HFe 2.5 P 2 W 18 O 62 23.H 2 O as a catalyst. HFe 2.5 P 2 W 18 O 62 23.H 2 O is a recyclable DAWSON-type heteropolyanion. Effects of various experimental parameters of the oxidation reaction of the dye were investigated. The studied parameters were the initial pH, the initial H 2 O 2 concentration, the catalyst mass, and the dye concentration. The optimum conditions had been determined, and it was found that efficiency of degradation obtained was about 100%. The optimal parameters were: initial pH 4; [H 2 O 2 ] 0 = 2 mM; catalyst mass 0.01 g; concentration of dye 30 mg/L. Infrared spectroscopy analysis of the HFe 2.5 P 2 W 18 O 62 23.H 2 O catalyst indicates that the catalyst showed good stability for degradation of AO7 even after second cycle.