The kinetics of electroreduction of peroxyacetic acid ͑PAA͒ 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 ͑m͒, the product (␣n a ) of the transfer coefficient and the number of electrons involved in the rate-determining step, and the number ͑n͒ of electrons involved in the overall electrode reaction were determined using cyclic voltammetry, hydrodynamic voltammetry, and hydrodynamic chronocoulometry. The Tafel slope ϭ 0.215 V/decade, m ϭ 1, k o ϭ 9.4 ϫ 10 Ϫ11 cm s Ϫ1 , ␣n a ϭ 0.32, and n ϭ 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.Organic peroxides have been used in a diverse range of industries, typically as oxidizing agents in organic syntheses, catalysts in polymerization reactions, bleaching reagents in the textile and paper industries, and disinfectants in the food industries. [1][2][3][4] Of these peroxides, H 2 O 2 has attracted special attention as an intermediate product in the electroreduction of oxygen; thus, its electrochemical behavior has been extensively studied. 5-18 Previous electrochemical studies on other peroxides have been mainly restricted to their polarographic behavior 19-23 with a view to finding a suitable method for their analysis. Recently, we developed a simple voltammetric method for the analysis of peroxyacetic acid ͑PAA͒. 24-26 As a continuation of previous papers, this study is devoted to clarifying the mechanism and kinetics of the electroreduction of PAA. This information is expected to be useful, for example, in finding an optimum condition for the electroanalysis of PAA and H 2 O 2 in their coexistence. [26][27][28][29][30] The electroreduction of PAA at a gold electrode was examined in acetate buffer solutions of various pH, because the gold electrode is most suitable as an electrode substrate for the voltammetric analysis of PAA. [24][25][26] The relevant kinetic and thermodynamic parameters ͑i.e., the Tafel slope, the formal potential of the PAA/acetic acid redox couple, k o , ␣n a , m, and n͒ were determined using cyclic voltammetry, steady-state voltammetry, and hydrodynamic chronocoulometry ͑HCC͒.
ExperimentalReagents.-Deionized water ͑Milli-Q, Millipore, Japan͒ was used to prepare all solutions. The PAA solutions of appropriate concentrations were prepared from its stock solutions ͑30% for H 2 O 2 and 39.4% for PAA͒. The equilibrium PAA ͑containing...
