title: The decoloration and mineralization of azo dye C.I. Acid Red 14 by sonochemical process: rate improvement via Fenton's reactions.
abstract: The degradation of azo dye C.I. Acid Red 14 (AR14) was investigated using cast iron in the absence and presence of low frequency ultrasound (59 kHz). The effects of pH, amount of cast iron ([Fe](0)) and initial concentration of AR14 ([dye](0)) on the degradation of AR14 by cast iron combined with low frequency ultrasound had been assessed. The degradation followed the first-order kinetics model. The first-order rate constant of AR14 degradation by cast iron was 7.50 x 10(-2) min(-1) while that by US-cast iron was 2.58 x 10(-1) min(-1). A 3.4-fold increase in the reaction rate was observed in the presence of ultrasound compared with that of absence of ultrasound. This kinetic effect is quantitatively accounted for a simple kinetic model based on the reaction of Fe(II) from cast iron in aqueous solution with sonochemically produced H(2)O(2) (Fenton's reaction). This latter effect illustrates a simple way of achieving a substantial improvement in the efficiency of sonochemical degradation reactions. It was found that for azo dye AR14, the rate of color decay was the first order with respect to the visible absorption of the dye. The destruction of the naphthalene rings in azo dyes was slower than that of color. A significant mineralization of AR14 was observed.
authors.affiliation: Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Lin
authors.forename: Xiao-Song
authors.initials: XS
authors.lastname: Zhao
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Zhi-Guo
authors.initials: ZG
authors.lastname: Yu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001673:Biodegradation, Environmental; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D014465:Ultrasonics; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: C469409:Acid red 14; D001391:Azo Compounds; D004396:Coloring Agents; D014874:Water Pollutants, Chemical; D007501:Iron