Electroreduction of peroxyacetic acid at gold electrode in aqueous media

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(o)), the electrochemical reaction order (m), the product (alphan(a)) of the transfer coefficient and the number of electrons 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 5 1, k(o) x 9.4 x 10(-11) cm s(-1), alphan(a) = 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 (H2O2) in the presence of acid catalyst and the standard redox potential of H2O2. 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. (C) 2004 The Electrochemical Society.