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a b s t r a c t Feasibility of degradation of Triton X-100 as a widely used and resistive surfactant in aqueous media was studied via some homogeneous and heterogeneous AOPs of UV/TiO 2 , UV/H 2 O 2 and UV/S 2 O 8 2− . For treatment of solutions containing 20 mg/L of Triton, the optimum obtained conditions are: 5.0 mg/L of nano TiO 2 , 270.3 mg/L of KPS, and 34.0 mg/L of H 2 O 2 (1 mM of the oxidants), initial natural pH of 5.4 and temperature of 45 • C. Under these conditions, the degradation efficiency for the UV/TiO 2 , UV/H 2 O 2 and UV/S 2 O 8 2−processes exceeds 71.9% (in 60 min), 80.9% (in 60 min) and 98.5% (in only 30 min) respectively. It was found that simultaneous application of these heterogeneous and homogeneous AOPs (UV/TiO 2 /H 2 O 2 or S 2 O 8 2− ) is not desirable due to some physico-chemical retarding effects. The influence of temperature on the reactions was examined in the range of 15-45 • C and a kinetic power law model jointed with the Arrhenius equation was introduced. A pseudo first order reaction rate is appropriate for UV/S 2 O 8 2− and UV/TiO 2 processes under optimum conditions, while this order for UV/H 2 O 2 process is 2.27. Meanwhile, the initial rates of degradation in UV/TiO 2 process can be described well by the Langmuir-Hinshelwood kinetic model. Analysis of energy consumptions (thermal and electrical) revealed that increasing in temperature is an effective factor for lowering the energy cost of the preferred process of UV/S 2 O 8 2− .

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