Mechanistic insight into oxidative degradation of some azo dyes with kinetic and thermodynamic analysis

Department of Chemistry, Kanya Gurukul Campus, Gurukul Kangri University, Haridwar-249 407, Uttarakhand, India E-mail : anjaligoel10@gmail.com, lasyal.rajni@gmail.com, abhilashakgc@gmail.com Manuscript received online 28 October 2014, accepted 12 February 2016 In this paper, an attempt has been made to get a kinetic and mechanistic insight into the oxidative degradation of azo dyes, Acid Red-14 and Acid Red-26 by hexacyanoferrate, abbreviated as HCF(III) ions spectrophotometrically at λmax of reaction mixture 515 and 507 nm respectively. The effect of various operational parameters such as the concentration of dye, oxidant, and solution pH on the reaction rate has been determined. The results show that the reaction follows first order kinetics with respect to [HCF(III)] and [Dye]. Thermodynamic parameters have been evaluated by studying the reaction rate at four different temperatures; 40 ºC to 55 ºC. Based on the experimental results a plausible reaction mechanism involving complex formation has been proposed and rate law has been derived. The degradation products were extracted by ethyl acetate and identified by LC-MS