Kinetic study of Orange II oxidation using peroxynitrous acid

The reaction of Orange II with peroxynitrous acid has been studied by a spectrophotometrical method. The reaction rate is complex because the order changes from zero to one in function of substrate and oxidant concentration. The influence of pH and ionic strength has been investigated, but their effect on the reaction rate appears to be negligible under the experimental conditions used. A reaction mechanism based on the experimental results is proposed, involving a radical cage solvent attack from peroxynitrous acid to Orange II. Copyright (C) 2009 John Wiley & Sons, Ltd.