Degradation of petroleum aromatic hydrocarbons using TiO₂ nanopowder film

Abstract

The performance of a photo-reactor packed with titanium dioxide (TiO₂) immobilized on glass beads, initiated by irradiation with natural and artificial ultraviolet (UV) sources, was evaluated in terms of the degradation efficiency of petroleum aromatic hydrocarbons. The effects of parameters such as pH, reaction time, hydrogen peroxide (H₂O₂) concentration and some ions were investigated. Additionally, the degradation of total organic carbon (TOC) and the formation of byproducts were studied. Photodegradation rates of benzene, toluene, ethylbenzene and xylenes (BTEX) by processes of UV/TiO₂ and UV/TiO₂/H₂O₂ were found to obey pseudo first-order kinetic models. Results indicated that the effect of pH value was negligible at the pH range of 5.5 to 8.5. TOC removal improved with addition of H₂O₂ demonstrating that a lack of hydrogen peroxide leads to incomplete mineralization. The effect of cations and anions on the photodegradation efficiencies of BTEX revealed that Mg²⁺ and Ca²⁺ caused the most deterioration in BTEX degradation efficiency. However and had the most salient inhibitory effects compared with other tested anions. The degradation efficiencies of both systems were investigated for the treatment of real polluted groundwater collected from the city of Tehran. Results showed that the degradation efficiencies of BTEX declined in the presence of inorganic and organic competitor species.

Keywords:

• advanced oxidation processes
• TiO₂ nanopowder film
• BTEX
• inhibitory salts
• groundwater remediation

Acknowledgements

The authors acknowledge the laboratory of faculty of environment at university of Tehran for BTEX analysis.