Dynamic electrode reconfiguration promotes in situ electrochemical peracetic acid synthesis for selective water decontamination

Abstract

In situ synthesis and activation of peracetic acid (PAA) for water decontamination is a promising way to overcome the transport and storage problems in PAA applications. Here, an in situ electrochemical PAA synthesis and activation system is constructed using RuO₂−Ti “active” electrode and graphite plate as the anode and the cathode, respectively. PAA is efficiently generated at the RuO₂−Ti anode with a maximum real-time concentration of ∼1020 μM and a negligible precursor loss of 2.91% after 180 min, and can be activated at the cathode to destruct a refractory pollutant (i.e., benzoic acid (BA)) with the rate constant of 0.22−0.28 h⁻¹, even under the interference of co-existing anions. Multiple pieces of evidence, including differential electrochemical mass spectrometry, sulfoxide probing test, and electron paramagnetic resonance spectroscopy, indicate that the oxygen-atom-transferring oxidation of CH₃COO⁻ by a high-valent ruthenium-oxo intermediate (i.e., RuO₃) in situ formed through the electrode reconfiguration between RuO₂ and chem-sorbed HO^• mainly accounts for PAA synthesis. Acetylperoxyl radical (CH₃C(O)OO^•) was evidenced as the dominant species for BA degradation. This study proposes an in situ strategy to electrochemically synthesize and activate PAA for selective water decontamination and enriches the understandings of the mechanism of “active” electrode in peroxide synthesis.