Decolorization and mineralization of Oolong tea polyphenols in colored soft drink wastewater by photo Fenton reaction

The decolorization and the mineralization of the colored soft drink wastewater including Oolong tea polyphenols by the photo Fenton reaction have been investigated. The decolorization of the colored soft drink wastewater including Oolong tea polyphenols by the photo Fenton reaction could be divided into 3 phases. Just after H2O2 was added to the solution, the color of the solution immediately increased from absorbance of 0.247 to 0.711 at the wavelength of 400 nm, which was defined as the 1st phase. Subsequently the significant decolorization by the photo Fenton reaction occurred at the 2nd phase. Finally, complete decolorization (the color attributed to the color of Fe3+) could be achieved in 180 min at the 3rd phase. The instantaneous and considerable color increase at the 1st phase could be attributed to the formation of intermediate colored compounds like quinones and soluble iron complexes produced by the Fenton reaction. About 95% mineralization of model colored soft drink wastewater with 229 mg L−1 initial TOC concentration was achieved after 165 min.