Catalytic Ozonation of Tartrazine Dye Wastewater Using NiAl₂O₄/NiO@γ-Al₂O₃: Catalyst Preparation and Performance

ABSTRACT

In this study, a novel NiAl₂O₄/NiO@γ-Al₂O₃ catalyst was prepared by the impregnation-calcination method and used for the catalytic ozonation of tartrazine wastewater. The NiAl₂O₄/NiO@γ-Al₂O₃ catalyst were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption experiments. It was found that NiAl₂O₄/NiO@γ-Al₂O₃ significantly improved the removal of chemical oxygen demand of the dye wastewater from 40% for the direct ozone oxidation to 65%, and the ozone concentration depletion for catalytic ozonation was 120% of that for ozone alone. The catalytic activity of the catalyst did not significantly decrease after reuse for six cycles and leaching concentration of metal ions less than 1%. However, the toxicity of the dye wastewater was greatly reduced after the catalytic ozonation. The pyridine Fourier transform infrared spectroscopy showed the catalytic ozonation reaction was related with Lewis acid sites. The presence of hydroxyl radicals, superoxide anion radicals, and singlet oxygen was verified by an electron paramagnetic resonance, and the quenching experiments confirmed that the removal of organic pollutants from the tartrazine wastewater mainly relied on hydroxyl radicals and singlet oxygen. Therefore, the NiAl₂O₄/NiO@γ-Al₂O₃ could be an effective catalyst for the rapid catalytic ozonation of dye wastewater.

KEYWORDS:

• catalytic mechanism
• catalytic ozonation
• dye wastewater
• hydroxyl radical
• NiAl₂O₄/NiO@γ-Al₂O₃
• singlet oxygen

Acknowledgments

The authors would like to thank the National Key Research and Development Program of China (2020YFB1506301) and the Dalian Science & Technology Innovation Fund projects (2022JJ12GX021) for the financial support of this work.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article or its supplementary materials.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the National Key Research and Development Program of China (2020YFB1506301) and the Dalian Science & Technology Innovation Fund projects (2022JJ12GX021).