Removal of Azo Dyes Acid Orange 7 (AO7) and Reactive Black 5 (RB5) by Metallic Iron: Kinetic Study

Bearing organic and inorganic pollutants, colored wastewater are an important source of environmental pollution. Removal dyes from dyestuff can be accomplished by various methods such as coagulationflocculation, Fenton regent, ozonation and so on. This work investigated metallic iron as an efficient and inexpensive material for treatment of colored wastewater. Parameters such as pH (3,, , 9 and 11), contact time (15, 30, 45, 60, 75, 90, 105 and 120 min), iron powder concentration (0.5, 1, 1.5 and 2 g/L) and initial dye concentration (25, 50, 75 and 100 mg/L) were studied. In addition, experimental data were fitted on pseudo- first order, pseudo-second order and modified pseudo-first order kinetic models. Result showed that dye removal was increased by increasing iron mass and contact time. While decreased by increasing pH of solution. Increasing initial dye concentration of AO7, has increased removal efficiency, while it was decreased by increasing initial dye concentration of RB5. In addition, results showed that pseudo-first order model best describe removal of AO7 (r2> 0.9708) and RB5 (r2>0.9776) by metallic iron. We concluded that metallic iron can be used as an effective an inexpensive matter for treatment of dyestuff waste.