1c:I[419806,["/_next/static/chunks/bb923814e1f4d2e9.js","/_next/static/chunks/dd3ee9f5b7716ca6.js","/_next/static/chunks/4204a0ae82542ca8.js","/_next/static/chunks/1270dead247da766.js","/_next/static/chunks/6e1aa89a642f40be.js","/_next/static/chunks/cd5e572bc3e4eb92.js","/_next/static/chunks/8ffd0b71567920d8.js","/_next/static/chunks/67ea6dfd21f16c5f.js","/_next/static/chunks/24eb4379f68013fd.js","/_next/static/chunks/b8cd775ffdf935bd.js","/_next/static/chunks/983103cd9eb7b428.js","/_next/static/chunks/d4ac9dcf27f6ff52.js","/_next/static/chunks/294b9525248c8e5f.js"],"default"] 1d:T525,Base is the most commonly used activator of persulfate for the treatment of contaminated groundwater by in situ chemical oxidation (ISCO). A mechanism for the base activation of persulfate is proposed involving the base-catalyzed hydrolysis of persulfate to hydroperoxide anion and sulfate followed by the reduction of another persulfate molecule by hydroperoxide. Reduction by hydroperoxide decomposes persulfate into sulfate radical and sulfate anion, and hydroperoxide is oxidized to superoxide. The base-catalyzed hydrolysis of persulfate was supported by kinetic analyses of persulfate decomposition at various base:persulfate molar ratios and an increased rate of persulfate decomposition in D(2)O vs H(2)O. Stoichiometric analyses confirmed that hydroperoxide reacts with persulfate in a 1:1 molar ratio. Addition of hydroperoxide to basic persulfate systems resulted in rapid decomposition of the hydroperoxide and persulfate and decomposition of the superoxide probe hexachloroethane. The presence of superoxide was confirmed with scavenging by Cu(II). Electron spin resonance spectroscopy confirmed the generation of sulfate radical, hydroxyl radical, and superoxide. The results of this research are consistent with the widespread reactivity reported for base-activated persulfate when it is used for ISCO.1e:T4d6,The initiation of ozone decomposition in "pure water" is first order in O₃ and OH^- concentration and k_O₃,OH^- becomes 70 ± 7 M^-1 s^-1 when a sequence of reactions is assumed by which three molecules of O₃ are eliminated per primary event. The difference between this value and higher values reported in the earlier literature may be explained by interferences by radical chain reactions which have not been totally inhibited in those studies. H₂O₂ also reacts with O₃ when present as an anion, HO₂^-. k_O₃,OH^- is (2.8 ± 0.5) × 10⁶ M^-1 s^-1 when it is assumed that 'two molecules of O₃ are eliminated per primary event. Therefore, whenever [H₂O₂] > 10^-7 M (pH <12), HO₂^- has a greater effect than OH^- on the decomposition rate of O₃ in water. The high reactivity of HO₂^- explains that H₂O₂ is observed as a significant intermediate in the ozonated water only if the pH is low, e.g., <6.1f:T5bd,

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References