Study on the efficiency and mechanism of Direct Red 80 dye by conventional ozonation and peroxone (O₃/H₂O₂) treatment

ABSTRACT

With the development of the dye industry, the treatment of dye wastewater needs to be solved urgently. In this work, conventional ozonation and peroxone (O₃/H₂O₂) processes were used to treat the Direct Red 80 dye wastewater, and the influence of relevant factors of the treatment efficiency was analyzed by using physicochemical methods including UV-visible absorption spectrum, three-dimensional fluorescence spectrum and ion chromatography. Through analysis of the oxidation mechanism under ozone treatment, a possible degradation pathway of Direct Red 80 was deduced. The results show that the decolorization rate of 100 mg/L dye wastewater after oxidation by ozone is 99%, and at pH = 12, the chemical oxygen demand (COD) removal rate is highest to 27.4%. In the process of peroxone (O₃/H₂O₂), under the same pH condition, when the dosing ratio of hydrogen peroxide and ozone is fixed at 1:10500, the chemical oxygen demand (COD) removal rate of Direct Red 80 dye wastewater can reach 40%, and under this ratio of addition, when the pH is 13, the chemical oxygen demand (COD) removal rate is the highest at 43%. These results indicated that the peroxone (O₃/H₂O₂) process of Direct Red 80 dye wastewater is better than ozone oxidation alone, and in both systems, the alkaline environment is more conducive to the decolorization and degradation of Direct Red 80 dye.

KEYWORDS:

• Direct Red 80 dye wastewater
• ozone oxidation
• hydrogen peroxide
• degradation mechanism

Acknowledgements

This work was supported by NSFC (21477067, 21777088 and U1806216), the Cultivation Fund of the Key Scientific and Technical Innovation Project, Research Fund for the Doctoral Program of Higher Education and Ministry of Education of China (708058, 20130131110016) Science and Technology Development Plan of Shandong Province (2014GSF117027) are also acknowledged.