Application of Advanced Oxidation Process Using Ozonation Assisted with Hydrogen Peroxide for Organic Compounds Removal from Bayer Liquor

ABSTRACT

One of the alumina industry’s main problems is the organic matter in the Bayer liquor during the Bayer Process released in the bauxite digestion process and accumulating in the process. It reduces as process efficiency and results in impurities in the final product. Several studies have shown that removing organic matter by ozonation can be attractive for industrial applications since ozone can be generated in situ and achieve faster results. For this reason, the goal of the present work was to study the removal of organic matter from the Bayer liquor. The effect of ozone dosage and O₃/H₂O₂ combination was evaluated at 40 °C and 80 °C. Results indicated that the organic matter mineralization achieved 19% at 80 °C, using 6.5 g/L of O₃ and 0.05 mol/L of H₂O₂, where 95.4% generated carbon dioxide. At the same conditions, 45.6% of oxalate was degraded. The UV/vis analyses demonstrated the decrease in organic chain size and the color of the samples before and after the oxidation process. An advanced oxidation process (O₃ and O₃/H₂O₂ combination) effectively removed a range of organic impurities from the Bayer liquor impacting the quality of the final product.

KEYWORDS:

• Ozonation
• peroxone process
• Bayer process
• humic acid
• oxalates

Acknowledgments

To the Fundação de Amparo à Pesquisa do Estado de São Paulo and Capes (grants: 2012/51871–9, São Paulo Research Foundation) for the financial support.

Additional information

Funding

Thanks to the University of Sao Paulo for supporting this project and to Fundação de Amparo à Pesquisa do Estado de São Paulo and Capes (FAPESP – grant 2012/51871-5, Sao Paulo Research Foundation) for financial support.