Photocatalytic oxidation of aquatic humic substances using TiO2/UV in a rotating photoreactor

Applicability of a rotating reactor for photocatalytic oxidation of humic substances extracted from the Han River in Seoul, Korea (Han-HS) was investigated. Because air blowing for complete dispersion of TiO2 photocatalysts could inhibit ultraviolet (UV)-irradiation between UV lamps and photocatalysts by air bubbles, a rotating photocatalytic reactor with four baffles was used for better UV-irradiation in this study. Han-HS was extracted and treated with UV-irradiation. Because Han-HS is different from other commercial humic materials (e.g. Aldrich Humic acid and International Humic Substance Society NOM), structural spectroscopic analyses were conducted by FT-IR and C-13-NMR. Immobilized TiO2 coated on hollow beads was used to separate and recover the photocatalyst. During two hours of UV-irradiation, absorbance at 254 nm (UV254) and total organic carbon (TOC) content were monitored. Photocatalytic oxidation efficiencies of different wavelengths of UV lamps (254 nm and 352 nm) were also compared and raw and pre-chlorinated waters of the Han River were used to evaluate the applicability for water treatment.