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

1,10-Dichlorodecane (D 2 C 10 ) is shown to be effectively photodegraded in aqueous suspensions of TiO 2 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 TiO 2 . The degradation rate was optimal with 150 mg/L of TiO 2 and a D 2 C 10 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 +, Cu 2+, and Fe 3+ ) had small effects on the degradation rate. The lack of transformation of D 2 C 10 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 D 2 C 10 onto the surface of the photocatalyst, confirmed that the reaction involved adsorbed 1,10-dichlorodecane and surface bound OH • radicals.