Catalytic ozonation of Acid Red B in aqueous solution over a Fe–Cu–O catalyst

• Fe–Cu mixed oxide catalyst was synthesized via citrate–nitrate combustion route.
• The catalyst notably improved the removal efficiency of Acid Red B compared to single ozonation.
• The catalyst has a good reusability and stability.
• The Fe–Cu–O catalytic ozonation of ARB was through direct and indirect oxidation.

The catalytic ozonation of Acid Red B (ARB) solution in the presence of Fe–Cu oxide (Fe–Cu–O) catalysts was investigated under different operating conditions. The effects of solution pH (3–11), ozone flow (3.6–30 mg/min) and initial ARB concentration (100–500 mg/L) on color and COD removal were evaluated. The optimum pH and ozone flow were determined to be 6.8 and 30 mg/min, respectively. In the presence of 1 g/L Fe–Cu–O powder, after 60 min, the color and the COD removal efficiency was 90% and 70%, while that of the single ozonation process was 66% and 48%, respectively. The repeated use of the catalyst proved that the Fe–Cu–O catalyst had a good reusability and stability. Finally, the possible mechanism of the catalytic ozonation of ARB was proposed, and the kinetics model of the color and COD degradation were established.