Effect of UV wavelength, temperature and photocatalyst on the removal of PAHs from industrial soil with photodegradation applications.

The aim of the present study was to evaluate the effectiveness of UV-based processes to the removal of PAHs from soils with and without photocatalyst. PAH removal experiments were conducted in a specially designed UV photochamber. The effects of various factors, namely temperature, light wavelength (UVA, UVC), TiO ₂ dose on the removal of PAHs were examined. Furthermore, evaporation ratios of PAHs during UV applications were determined with polyurethane foam (PUF) samples. Temperature increase positively affected PAH removal process. The total 12 (∑ ₁₂ ) PAH content reduced by 86-90% in the soil samples during UV applications. With the use of UVA rays, higher ∑ ₁₂ PAH removal was enhanced when compared to UVC rays. It was thought that in the existence of UVC rays, other aromatic compounds or other PAHs in soil converted to targeted PAHs with photodegradation. The amounts of evaporated PAHs from soil were increased with increasing of temperature and more than 90% of PAHs in the air consisted of 3-4 ring compounds. It was found that TiO ₂ provided an increase in removal ratios and ∑ ₁₂ PAHs removal ratios changed between 87% and 94%. Furthermore, the amount of PAH migrated to the air decreased during this application. During UVA-TiO ₂ and UVC-TiO ₂ applications, at 30°C, evaporated average ∑ ₁₂ PAH amounts were 2.91 ng/m ³ and 6.59 ng/m ³ , respectively.