This study reexamined the mechanisms for oxidative organic degradation by the binary mixture of periodate and H2O2 (PI/H2O2) that was recently identified as a new advanced oxidation process. Our findings conflicted with the previous claims that (i) hydroxyl radical (•OH) and singlet oxygen (1O2) contributed as the primary oxidants, and (ii) •OH production resulted from H2O2 reduction by superoxide radical anion (O2 •–). PI/H2O2 exhibited substantial oxidizing capacity at pH < 5, decomposing organics predominantly by •OH. The likelihood of a switch in the major oxidant under varying pH conditions was revealed. IO4 – as the major PI form under acidic conditions underwent one-electron reduction by H2O2 to yield radical intermediates, whereas H2I2O10 4– preferentially occurring at pH > 7 caused 1O2 generation through two-electron oxidation of H2O2. PI reduction by O2 •– was suggested to be a key reaction in •OH production, on the basis of the electron paramagnetic resonance detection of methyl radicals in the dimethyl sulfoxide solutions containing PI and KO2, and the absence of deuterated and 18O-labeled hydroxylated intermediates during PI activation using D2O and H2 18O2. Finally, simple oxyanion mixing subsequent to electrochemical PI and H2O2 production achieved organic oxidation, enabling a potential strategy to minimize the use of chemicals.

This study is the first to demonstrate the capability of Cl − to markedly accelerate organic oxidation using thermally activated peroxymonosulfate (PMS) under acidic conditions. The treatment efficiency gain allowed heat-activated PMS to surpass heat-activated peroxydisulfate (PDS). During thermal PMS activation at excess Cl − , accelerated oxidation of 4-chlorophenol (susceptible to oxidation by hypochlorous acid (HOCl)) was observed along with significant degradation of benzoic acid and ClO 3 − occurrence, which involved oxidants with low substrate specificity. This indicated that heat facilitated HOCl formation via nucleophilic Cl − addition to PMS and enabled free chlorine conversion into less selective oxidizing radicals. HOCl acted as a key intermediate in the major oxidant transition based on temperaturedependent variation in HOCl concentration profiles, kinetically retarded organic oxidation upon NH 4 + addition, and enabled rapid organic oxidation in heated PMS/HOCl mixtures. Chlorine atom that formed via the one-electron oxidation of Cl − by the sulfate radical served as the primary oxidant and was involved in hydroxyl radical production. This was corroborated by the quenching effects of alcohols and bicarbonates, reactivity toward multiple organics, and electron paramagnetic resonance spectral features. PMS outperformed PDS in degrading benzoic acid during thermal activation operated in reverse osmosis concentrate, which was in conflict with the wellestablished superiority of heat-activated PDS.

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Monitoring the dynamics of proteins in live cells on appropriate spatiotemporal scales may provide key information regarding long-standing questions in molecular and cellular regulatory mechanisms. However, tools capable of imaging the conformational changes over time have been elusive. Here, we present a single-molecule stroboscopic imaging probes by developing gyroscopic plasmonic nanoparticles, allowing for replication of protein–protein interactions and the conformational dynamics based on rotational and lateral velocities. This study fundamentally monitors the rotational motion of a membrane protein, epidermal growth factor receptor (EGFR), to decipher undiscovered structural dynamics in live cells without any molecular perturbations. This method offers a strategy to visualize assemblies and conformational changes, and provides unique insights into the mechanism underlying the molecular dynamics for receptors.

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