Investigation on the Removal of COD from Colored Aqueous Solutions with O₃, H₂O₂, HCO₃⁻, and PAC

Abstract

In this study, chemical oxygen demand (COD) was removed using different processes containing O₃, H₂O₂, HCO₃⁻, and powder activated carbon (PAC) from the synthetic dye solutions. The effects of the experimental parameters such as temperature, ozone dose, dye concentration, pH, and time on the removal of COD were investigated. The Taguchi method was applied to determine the optimum conditions. An orthogonal array L₁₈ (2¹ * 3⁷) experimental design plan was selected to define the optimum conditions. In addition, the mechanism of the COD removal was explained on the basis of the results of Fourier transform infrared (FTIR) spectroscopy. To gain information about COD removal mechanism at various pHs, electrophoretic mobilities of particles were measured. The chosen experimental parameters and their ranges are: (0–39 mM); temperature (18–70 °C); ozone dose (164–492 mg/min); dye concentration (200–600 ppm); PAC (0–1.5 g); H₂O₂ (0–0.056 mM); pH (3–12); and time (10–30 min). Under these optimum conditions, it was found that the COD removal efficiency from the synthetic dye solutions was 98%.

Keywords:

• Ozone
• Bicarbonate Ion
• COD Removal
• Hydrogen Peroxide
• Powdered Activated Carbon (PAC)