Thermodynamic properties of an emerging chemical disinfectant, peracetic acid

Highlights: • Peracetic acid (PAA or CH₃COOOH) is a promising disinfectant alternative to chlorine. • This work for the first time summarized the thermodynamic properties of PAA. • The standard Gibbs energy of formation of CH₃COOOH_(aq) is − 299.41 kJ·mol^{− 1}. • The standard Gibbs energy of formation of CH₃COOO_(aq)⁻ is − 252.60 kJ·mol^{− 1}. • The standard redox potential of PAA is 1.748 V vs. standard hydrogen electrode (pH 0). Peracetic acid (PAA or CH₃COOOH) is an emerging disinfectant with a low potential to form carcinogenic disinfection by-products (DBPs). Basic thermodynamic properties of PAA are, however, absent or inconsistently reported in the literature. This review aimed to summarize important thermodynamic properties of PAA, including standard Gibbs energy of formation and oxidation-reduction (redox) potential. The standard Gibbs energies of formation of CH₃COOOH_(aq), CH₃COOOH_(g), CH₃COOOH_(l), and CH₃COOO_(aq)⁻ are − 299.41 kJ·mol^{− 1}, − 283.02 kJ·mol^{− 1}, − 276.10 kJ·mol^{− 1}, and − 252.60 kJ·mol^{− 1}, respectively. The standard redox potentials of PAA are 1.748 V and 1.005 V vs. standard hydrogen electrode (SHE) at pH 0 and pH 14, respectively. Under biochemical standard state conditions (pH 7, 25 °C, 101,325 Pa), PAA has a redox potential of 1.385 V vs. SHE, higher than many disinfectants. Finally, the environmental implications of the thermodynamic properties of PAA were systematically discussed. Those properties can be used to predict the physicochemical and biological behavior of aquatic systems exposed to PAA.