Degradation of Azo Dye Reactive Black 5 and Acid Orange 7 by Fenton-Like Mechanism

Colored wastewater is one of the most important sources of environmental pollution and because of their visibility and bearing toxic chemicals, it is very important to be treated before released into the environment. In recent years, several methods have been used for treatment of dyestuff effluents. In this work, removal of two azo dyes, Acid Orange 7 and Reactive Black 5 as an indicator of synthetic dyes by Fenton-like reaction were studied. In this process, radicals will be generated by using and UV light, so it can occur without the addition of hydrogen peroxide. Various parameters such as pH, amount of iron powder, initial dye concentration, UV light and contact time were studied in terms of their effect on the reaction progress. It is observed that high removal of dyes for UV system was obtained at pH=11, while in the and /UV system, high removal occurred at pH=3. Removal of dye was increased by increasing the iron mass and contact time. High removal of dye was at the time equivalent of 120 min and reached equilibrium. Initial dye concentration has different effects for Acid Orange 7 and Reactive Black 5 removal. Increasing the initial dye concentration of Acid Orange 7 has increased dye removal in the /UV and system, while it was decreased in the UV system. For RB5 removal, it was decreased in the /UV and system by increasing the initial dye concentration, while it increased in UV system.