Heterogeneous photocatalytic ozonation of 2,4-D in dilute aqueous solution with TiO2 fiber
| Autor: | Hiroaki Ozaki, Shogo Taniguchi, Rabindra Raj Giri, R. Takanami |
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| Rok vydání: | 2008 |
| Předmět: |
Titanium
Environmental Engineering Ozone Aqueous solution Photochemistry Inorganic chemistry Waste Disposal Fluid Decomposition Catalysis Water Purification Solutions Kinetics chemistry.chemical_compound Reaction rate constant chemistry Chemical engineering Photocatalysis Hydroxyl radical 2 4-Dichlorophenoxyacetic Acid Oxidation-Reduction Dissolution Water Pollutants Chemical Water Science and Technology |
| Zdroj: | Water Science and Technology. 58:207-216 |
| ISSN: | 1996-9732 0273-1223 |
| DOI: | 10.2166/wst.2008.633 |
| Popis: | Photocatalytic ozonation (O 3 /UV/TiO 2 ) is an emerging oxidation method for recalcitrant organic contaminants in water. However, immobilised TiO 2 catalysts suffer from reduced photonic efficiency. Therefore, TiO 2 catalysts with excellent mechanical and thermal properties and enhanced photonic efficiencies are sought. This paper aimed to elucidate the mineralisation of low concentration 2,4-D (45.0 μM) by O 3 /UV/TiO 2 using the world9s first high-strength TiO 2 fibre in laboratory batch experiments. 2,4-D degradation and TOC removal followed pseudo first-order reaction kinetic. The removal rates for 2,4-D and TOC in O 3 /UV/TiO 2 were 1.5 and 2.4-fold larger than the summation of the values for ozonation (O 3 ) and photocatalysis (UV/TiO 2 ), respectively. O 3 /UV/TiO 2 was characterised by few aromatic intermediates with low abundance, fast degradations of aliphatic intermediates and dechlorination as a major step. The significantly enhanced 2,4-D mineralisation in O 3 /UV/TiO 2 was attributed to increased ozone dissolution and decomposition, and reduced electron–hole recombination resulting in large number of hydroxyl radical ( • OH) formation from more than one parallel path. The discrepancies in the organic carbon mass budget were attributed to few apparently major unidentified intermediates, while chlorine mass balance was reasonably acceptable. The mineralisation efficiency of O 3 /UV/TiO 2 with the TiO 2 fibre can further be enhanced by optimisation of experimental design parameters. The new TiO 2 fibre is very promising to overcome the problem of reduced efficiency of TiO 2 catalyst in an immobilised state. |
| Databáze: | OpenAIRE |
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