Solar photocatalytic degradation of groundwater contaminated with petroleum hydrocarbons

To evaluate the potential use for ex situ remediation, a solar-driven, photocatalyzed reactor system was constructed and applied to the treatment of groundwater contaminated with benzene, toluene, ethylbenzene, and xylene (BTEX) and total petroleum hydrocarbons (TPHs) near a gas station using selected advanced oxidation processes such as H2O2/solar light, TiO2 slurry/solar light, and immobilized TiO2/solar light. Groundwater samples containing BTEX and TPH, loaded with H2O2 or slurry and immobilized TiO2 catalyst, were exposed to solar light (37° N and 128° E) in winter with an average intensity of 1.6 mW/cm2 measured at 365 nm. Whereas the solar light/TiO2 slurry system achieved >70% degradation of BTEX and TPH within 4 h, the solar light/immobilized TiO2 and solar light/H2O2 systems did not show significant removal within the same time. However, both TiO2 slurry and immobilized systems were able to reduce BTEX and TPH levels effectively if H2O2 (10 mM) was added. The degradation rates of low molecular weight gasoline (BTEX) and n-alkanes ranging from C10 to C15 were higher than those of n-alkanes ranging from C16 to C20. The removal efficiency of BTEX and TPH in the groundwater samples also increased with a larger solar collector area of the reactor. © 2006 American Institute of Chemical Engineers Environ Prog, 2006