The utilization of dye wastewater in enhancing catalytic activity of CeO 2 -TiO 2 mixed oxide catalyst for NO reduction and dichloromethane oxidation.

Waste is a misplaced resource. Herein, anionic (orange II sodium salt and Ponceau 2R) and cationic (Rhodamine B and Methylene blue) dye wastewater assisted photo-treatment (referred as DAPT) method was developed to modify sol-gel synthesized CeO ₂ -TiO ₂ (CeTi) mixed oxide catalyst. Catalytic activity test results showed that both anionic and cationic dye wastewater could be used as "fuel" of photo-treatment to enhance the activity of CeTi catalyst in NO reduction and dichloromethane oxidation. Characterization and DFT calculation results revealed that DAPT process increased the amount of Ce ³⁺ ions on CeTi samples, which could induce the formation of Ce-V _O -Ti (oxygen vacancy (V _O ) in Ce-O-Ti short range structure). These Ce-V _O -Ti defects not only could be adsorption sites for NH ₃ , dichloromethane and oxygen, but also promoted the redox shift of Ce ³⁺ + Ti ⁴⁺ ⇋ Ce ⁴⁺ + Ti ³⁺ by enhancing the oxidizability of Ce ⁴⁺ and Ti ⁴⁺ species. Furthermore, defects changed the polarity of Ce-O and Ti-O, which was conducive to the activation of lattice oxygen. All these improvements contributed to the excellent catalytic activity of CeTi catalysts. We expected this work to be instructive on constructing structure-activity over CeO ₂ -TiO ₂ based catalysts and utilizing dye wastewater.
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