title: Synergy of ozonation and photocatalysis to mineralize low concentration 2,4-dichlorophenoxyacetic acid in aqueous solution.
abstract: Concentration of 2,4-dichlorophenoxyacetic acid (2,4-D) may affect its degradation kinetics in advanced oxidation systems, and combinations of two or more systems can be more effective for its mineralization at low concentration levels. Degradations and mineralizations of 0.045mM 2,4-D using O(3), O(3)/UV, UV/TiO(2) and O(3)/UV/TiO(2) systems were compared, and influence of reaction temperature on the mineralization in O(3)/UV/TiO(2) system was investigated. 2,4-D degradations by O(3), O(3)/UV and UV/TiO(2) systems were similar to the results of earlier investigations with higher 2,4-D concentrations. The degradations and total organic carbon (TOC) removals in the four systems were well described by the first-order reaction kinetics. The degradation and removal were greatly enhanced in O(3)/UV/TiO(2) system, and further enhancements were observed with larger O(3) supplies. The enhancements were attributed to hydroxyl radical (()OH) generation from more than one reaction pathway. The degradation and removal in O(3)/UV/TiO(2) system were very efficient with reaction temperature fixed at 20 degrees C. It was suspected that reaction temperature might have influenced ()OH generation in the system, which needs further attention.
authors.affiliation: New Industrial R&D Center, Osaka Sangyo University, 3-1-1 Nakagaito, Daito City, 574-8530 Osaka, Japan. sn04001@sub.osaka-sandai.ac.jp
authors.forename: Rabindra Raj
authors.initials: RR
authors.lastname: Giri
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ozaki
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ishida
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takanami
authors.forename: Shogo
authors.initials: S
authors.lastname: Taniguchi
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis / Q000737:chemistry*; D002384:Catalysis; D007700:Kinetics; D010126:Ozone / Q000737:chemistry*; D010777:Photochemistry / Q000379:methods; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D015084:2,4-Dichlorophenoxyacetic Acid; D010126:Ozone; D014025:Titanium