Photocatalytic Degradation of Brilliant Red Dye and Textile Wastewater

The degradation of textile wastewater and brilliant red dye solutions in a coil photoreactor provided with recirculation, assisted by powdered TiO₂ and medium-pressure mercury lamp irradiation, was investigated. Factorial design was used for the attainment of the best conditions for COD and color abatement. pH and TiO₂ loading showed to be critical variables for the photocatalytic degradation process for both textile wastewater and aqueous reactive dye solutions (25 mg L⁻¹). For both substrates, the optimized process conditions by factorial design were almost the same (pH 2–3, 444 mg TiO₂ L⁻¹ loading, 5 L h⁻¹ recirculation flow-rate). A 41% COD abatement for textile wastewater was obtained with a 120 min treatment. For the Brilliant Red dye solutions, a 20 min treatment resulted in about 90% decolorization (517 nm, pH 5), as well as in a reduction of 66% of the integrated absorbance (200–600 nm, pH 5).

Key Words:

• Photocatalytic treatment
• Textile wastewater
• Dye
• Coil photoreactor.

ACKNOWLEDGMENTS

The authors wish to thank the Brazilian agency CNPq for the scholarships and financial support.

Notes

*Bio- and chemical oxygen demand.