Prehydrated Electrons Activated by Continuous Electron Transfer Stemmed from Peracetic Acid Homolysis Mediated by Diamond Surface Defects for Enhanced PFOA Destruction

Research on the use of peracetic acid (PAA) activated by nonmetal solid catalysts for the removal of dissolved refractory organic compounds has gained attention recently due to its improved efficiency and suitability for advanced water treatment (AWT). Among these catalysts, nanocarbon (NC) stands out as an exceptional example. In the NC-based peroxide AWT studies, the focus on the mechanism involving multimedia coordination on the NC surface (reactive species (RS) path, electron reduction non-RS pathway, and singlet oxygen non-RS path) has been confined to the one-step electron reaction, leaving the mechanisms of multichannel or continuous electron transfer paths unexplored. Moreover, there are very few studies that have identified the nonfree radical pathway initiated by electron transfer within PAA AWT. In this study, the complete decomposition (kobs = 0.1995) and significant defluorination of perfluorooctanoic acid (PFOA, deF% = 72%) through PAA/NC has been confirmed. Through the use of multiple electrochemical monitors and the exploration of current diffusion effects, the process of electron reception and conduction stimulated by PAA activation was examined, leading to the discovery of the dynamic process from the PAA molecule → NC solid surface → target object. The vital role of prehydrated electrons (epre–) before the entry of resolvable electrons into the aqueous phase was also detailed. To the best of our knowledge, this is the first instance of identifying the nonradical mechanism of continuous electron transfer in PAA-based AWT, which deviates from the previously identified mechanisms of singlet oxygen, single-electron, or double-electron single-path transfer. The pathway, along with the strong reducibility of epre– initiated by this pathway, has been proven to be essential in reducing the need for catalysts and chemicals in AWT.