title: Influence of various reaction parameters on 2,4-D removal in photo/ferrioxalate/H(2)O(2) process.
abstract: The influence of various reaction parameters on herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) removal were examined in the photo/ferrioxalate/H(2)O(2) system, with regard to: (1) sulfate, phosphate, and z.rad;OH scavenger, as solution constituent; and (2) light intensity, ferrioxalate, H(2)O(2), and oxalate concentration, as operating parameter. In terms of 2,4-D removal, the photo/ferrioxalate/H(2)O(2) system has always been superior to the photo/Ferric ion/H(2)O(2) system, despite the high presence of anions (sulfate 100 mM, phosphate 1 mM) or z.rad;OH scavenger. Not only the rate of 2,4-D removal, but also the decomposition rate of H(2)O(2) and oxalate proportionally increase with light intensity. The ferrioxalate concentration determines the light absorption fraction, and thus, controls the rates of 2,4-D removal, and the decomposition of H(2)O(2) and oxalate, are predicted from kinetic formulations. The optimal concentration of H(2)O(2) and oxalate, according to the extent of the z.rad;OH scavenging reaction with these reagents, has been demonstrated for 2,4-D removal. It was found that an increasing oxalate concentration, which bears the burden of increased dissolved organic carbon (DOC), does not occur. This is because its decomposition, as a result of the photochemical reduction of the ferric oxalate complex, results in a decrease of the equivalent DOC. The importance of the key reaction factors to be considered, when applying this system to real wastewater treatment, is also discussed.
authors.affiliation: School of Chemical Engineering, College of Engineering, Seoul National University, Kwanak Ku, Shilimdong san 56-1, South Korea.
authors.forename: Yunho
authors.initials: Y
authors.lastname: Lee
authors.forename: Joonseon
authors.initials: J
authors.lastname: Jeong
authors.forename: Changha
authors.initials: C
authors.lastname: Lee
authors.forename: Soomyung
authors.initials: S
authors.lastname: Kim
authors.forename: Jeyong
authors.initials: J
authors.lastname: Yoon
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry / Q000302:isolation & purification*; D006540:Herbicides / Q000737:chemistry / Q000302:isolation & purification*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010777:Photochemistry; D014865:Waste Disposal, Fluid / Q000379:methods; D018508:Water Purification / Q000379:methods
chemical_list: D006540:Herbicides; D010070:Oxalates; D016877:Oxidants; C034942:ferrioxalate; D015084:2,4-Dichlorophenoxyacetic Acid; D006861:Hydrogen Peroxide