Photocatalytic Degradation of 1,10-Dichlorodecane in Aqueous Suspensions of TiO2:  A Reaction of Adsorbed Chlorinated Alkane with Surface Hydroxyl Radicals

1,10-Dichlorodecane (D2C10) is shown to be effectively photodegraded in aqueous suspensions of TiO2 using a photoreactor equipped with 300 nm lamps. Solutions exposed to UV light intensities of 3.6 × 10-5 Ein L-1 min-1, established by ferrioxalate actinometry, showed negligible direct photolysis in the absence of TiO2. The degradation rate was optimal with 150 mg/L of TiO2 and a D2C10 concentration (240 μg/L) approaching its solubility limit. Kinetics of photodegradation followed a Langmuir−Hinshelwood model suggesting that the reaction occurred on the surface of the photocatalyst. The presence of h+ vb and OH• radical scavengers, including methanol and iodide, inhibited the degradation supporting a photooxidation reaction. Electron scavengers (Ag+, Cu2+, and Fe3+) had small effects on the degradation rate. The lack of transformation of D2C10 in acetonitrile as solvent indicated that the major oxidants were OH• radicals. The presence of tetranitromethane, effectively eliminating the formation of free OH• radicals, did not affect the degradation rates significantly. This result, combined with observed increases in photolysis rates with the degree of adsorption of D2C10 onto the surface of the photocatalyst, confirmed that the reaction involved adsorbed 1,10-dichlorodecane and surface bound OH• radicals.