This paper denotes the importance of operational parameters for the feasibility of ozone (O3) oxidation for the treatment of wastewaters containing 1,4-dioxane. Results show that O3 process, which has formerly been considered insufficient as a sole treatment for such wastewaters, could be a viable treatment for the degradation of 1,4-dioxane at the adequate operation conditions. The treatment of both synthetic solution of 1,4-dioxane and industrial wastewaters, containing 1,4-dioxane and 2-methyl-1,3-dioxolane (MDO), showed that about 90% of chemical oxygen demand can be removed and almost a total removal of 1,4-dioxane and MDO is reached by O3 at optimal process conditions. Data from on-line Fourier transform infrared spectroscopy provides a good insight to its different decomposition routes that eventually determine the viability of degrading this toxic and hazardous compound from industrial waters. The degradation at pH>9 occurs faster through the formation of ethylene glycol as a primary intermediate; whereas the decomposition in acidic conditions (pH<5.7) consists in the formation and slower degradation of ethylene glycol diformate.

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1This study reports the synthesis and characterization of composite nitrogen and fluorine 2 co-doped titanium dioxide (NF-TiO2) for the removal of contaminants of concern 3 (COCs) in wastewater under visible and solar light. Monodisperse anatase TiO2 4 nanoparticles of different sizes and Evonik P25 were assembled to immobilized NF-5TiO2 by direct incorporation into the sol-gel or by the layer-by-layer technique. The 6 composite films were characterized with X-ray diffraction, high resolution-transmission 7 electron microscopy, environmental scanning electron microscopy, and porosimetry 8 analysis. The photocatalytic degradation of atrazine, carbamazepine, and caffeine was 9 evaluated in a synthetic water solution and in an effluent from a hybrid biological 10 concentrator reactor (BCR). Minor aggregation and improved distribution of 11 monodisperse titania particles was obtained with NF-TiO2-monodisperse (10 and 50 12 nm) from the layer-by-layer technique than with NF-TiO2 + monodisperse TiO2 (300 13 nm) directly incorporated into the sol. The photocatalysts synthesized with the layer-by-14 layer method achieved significantly higher degradation rates in contrast with NF-TiO2-15 monodisperse titania (300 nm) and slightly faster values when compared with NF-TiO2-16 P25. Using NF-TiO2 layer-by-layer with monodisperse TiO2 (50 nm) under the solar 17 light irradiation, the respective degradation rates in synthetic water and BCR effluent 18 were 14.6 and 9.5  10

1The treatment of 1,4-dioxane solution by electrochemical oxidation on boron-doped 2 diamond was studied using a central composite design and the response surface 3 methodology to investigate the use of SO4 2-and HCO3