Electroreduction of Peroxyacetic Acid at Gold Electrode in Aqueous Media

Abstract

The kinetics of electroreduction of peroxyacetic acid (PAA) has been studied at a gold electrode in acetate buffer solutions of pH in the range 3-6. The electroreduction of PAA was irreversible. The relevant kinetic parameters including the Tafel slope, the standard rate constant (k°), the electrochemical reaction order (m), the product (an J of the transfer coefficient and the number of elections involved in the rate-determining step, and the number (n) of electrons involved in the overall electrode reaction were determined using cyclic voltammetry, hydrodynamic voltammetry, and hydrodynamic chronocoulometry. The Tafel slope = 0.215 V/decade, m = 1, k°= 9.4 × 10 -11 cms -1 , αn 2 = 0.32, and n = 2. The formal potential of the PAA/acetic acid redox couple was also theoretically calculated to be 1.762 V vs. Ag/AgCl based on the equilibrium constant for the reaction of PAA and hydrogen peroxide (H 2 O 2 ) in the presence of acid catalyst and the standard redox potential of H 2 O 2 . The diffusion coefficient of PAA was also estimated. Based on the obtained results, the overall electroreduction of PAA is considered to be composed of two one-electron reduction steps with the formation of acetate or hydroxyl radical as probable reaction intermediates. © 2004 The Electrochemical Society. All rights reserved.