Solar-Chemical Treatment of Groundwater Contaminated with Petroleum at Gas Station Sites: Ex Situ Remediation Using Solar/TiO₂ Photocatalysis and Solar Photo-Fenton

Groundwater samples contaminated by BTEX (benzene, toluene, ethylbenzene, xylene isomers and TPHs (total petroleum hydrocarbons) were treated with advanced oxidation processes (AOPs), such as TiO₂ photocatalysis and Fe²⁺/H₂O₂ exposed to solar light (37°N and 128°E) with an average intensity of 1.7 mW/cm² at 365 nm. These AOP processes showed feasibility in the treatment of groundwater contaminated with BTEX, TPH and TOC (Total Organic Carbon). Outdoor field tests showed that the degradation efficiency of each contaminant was higher in the Fe²⁺/H₂O₂ system without solar light compared to the TiO₂/solar light and H₂O₂/solar light systems. However, the TiO₂/solar light and the Fe²⁺/H₂O₂/solar light systems showed significantly enhanced efficiencies in the degradation of BTEX, TPH and TOC with the additional use of H₂O₂. Near complete degradation of BTEX and TPH was observed within 2 and 4 hrs, respectively, however, that of TOC was slower. Without pretreatment of the groundwater, fouling of the TiO₂, due to the ionic species present, was observed within 1 hr of operation, which resulted in the inhibition of further BTEX, TPH and TOC destruction. The degradation rate of n-alkanes with carbon numbers ranging from C10 to C15 was relatively greater than that of n-alknaes with carbon numbers ranging from C16 to C20. From this work, the AOP process (Fe²⁺/H₂O₂/solar light and TiO₂/H₂O₂/solar light) illuminated with solar light was identified as an effective ex situ technique in the remediation of groundwater contaminated with petroleum.

Key Words:

• Groundwater
• BTEX
• TPH
• TOC
• H₂O₂
• TiO₂
• Fe²⁺/H₂O₂
• TiO₂/Solar light
• n-alkanes
• Gas station.

ACKNOWLEDGMENTS

This work was partly supported by the RRC program of Ministry of Commerce, Industry and Energy.