Decolorization of Reactive Red K-2BP wastewater in fixed-bed column system packed sponge iron

The decolorization of Reactive Red K-2BP wastewater with sponge iron in a fixed-bed column system was evaluated at different influent water qualities (pH, dye concentration), particle diameter of sponge iron and filtrate rate. The decolorization efficiencies at influent pH of 6 were superior to those at influent pH of 5 and 7.5. The decolorization efficiency decreased with increments of filtration rate, influent dye concentration and particle size of the sponge iron. Under optimal conditions, over 94% of decolorization efficiency could be obtained. X-ray diffraction (XRD) of sponge iron showed Fe⁰ was transformed to Fe_3.6O_0.4(O, OH, Cl)₉, magnetite (Fe+2Fe₂+3O₄) and lepidocrocite Fe+3O(OH) after the reaction.