ABSTRACT
Laboratory experiments were conducted to study the photocatalytic capability of amorphous α-Fe2O3 to degrade polycyclic aromatic hydrocarbons (PAHs). Solutions containing 16 US EPA priority PAHs were spiked with Fe2O3 and incubated in a climate chamber at stable conditions of temperature (20°C) and light (9.6 W·m−2) for 28 days. In addition, samples without Fe2O3 were also incubated. PAHs levels were monitored by means of GC–MS, and their toxicity was assessed using Microtox® bioassay. Fe2O3 had a significant photocatalytic effect on fluorene, phenanthrene, and benzo(a)pyrene, the photodegradation rate of the latter being 71% and 50% in presence and absence of Fe2O3, respectively. On the other hand, photolysis was significantly higher than photocatalysis for benzo(a)anthracene and dibenzo(ah)anthracene. Photodegradation of anthracene was notably the same regardless of Fe2O3 presence. Remaining PAHs were not photodegraded, neither with, nor without Fe2O3. These results indicated that, in some cases, Fe2O3 might act as a shield for PAHs by hindering their photodegradation. Other factors, such as the chemical structure of the Fe2O3, and also the absence of the soil matrix components (i.e., humic acid, other metals oxides, and texture) could also play a role. Photodegradation trends were supported by changes of EC50 values, suggesting the formation of more bioavailable or toxic PAHs by-products when Fe2O3 and light were present.
Acknowledgments
The authors are indebted to Dr. Irene Maijó for her excellent guidance and assistance in GC–MS analysis