15092-81-6Relevant articles and documents
Reaction of peroxyl radicals with ozone in water
Lind, Johan,Merenyi, Gabor,Johansson, Erik,Brinck, Tore
, p. 676 - 681 (2003)
The reactivity of alkylperoxyl radicals and -O3SOO toward ozone was investigated. The peroxyl radicals were produced by steady-state γ-radiolysis in the presence of O3. The rate constants were extracted from the decay rate of ozone measured during the irradiation. The rate constants vary between 7 × 103 and 2 × 105 M-1 s-1 and there is a trend of increasing rate constant with electron-withdrawing substituent. Quantum chemical computations support a mechanism, according to which formation of an alkyl trioxide radical is the rate-determining step. This is followed by rapid expulsion of O2 to yield the alkoxyl radical. Conceivably, the alkyl trioxide radical is preceded by an extremely unstable alkyl pentoxide radical in equilibrium with the reactants.
Photoelectrochemical reaction for the efficient production of hydrogen and high-value-added oxidation reagents
Fuku, Kojiro,Wang, Nini,Miseki, Yugo,Funaki, Takashi,Sayama, Kazuhiro
, p. 1593 - 1600 (2015/05/20)
A porous and thick photoelectrode of WO3 in the monoclinic phase was prepared to realize the recovery of H2 and high-value-added oxidation reagents with efficient solar energy conversion. The WO3 photoelectrode enabled the efficient production and accumulation of O2, S2O82-, Ce4+, and IO4- as oxidation products. Most notably, S2O82-, which possesses the highest oxidizability among all the peroxides, was generated with high applied bias photon-to-current efficiency (2.2 %) and faraday efficiency (≈100 %) upon irradiation from the back side of the photoelectrode. The design of a tandem photoelectrode system combining a dye-sensitized solar cell (DSSC) was also challenged for the realization of this photoelectrode system without external bias. A high solar energy conversion efficiency (5.2 %) was achieved in the tandem system comprising the WO3 photoelectrode connected to two DSSCs with a near-IR-utilizing dye in series for the production of H2 and S2O82-.
Reactivity and role of SO5?- radical in aqueous medium chain oxidation of sulfite to sulfate and atmospheric sulfuric acid generation
Das, Tomi Nath
, p. 9142 - 9155 (2007/10/03)
This study reevaluates the role of peroxymonosulfate anion radical (-O3SOO? or SO5?-) intermediate during radical-induced chain oxidation of HSO3-/SO32- in oxygenated aqueous solution. The SO5?- radical absorption band in the UV is weak: ε = 1065 ± 80 M-1 cm-1 at λmax (260-265 nm). The SO5?- radical takes part in two radical-radical and four radical-solute reactions, partially producing the other chain carrier, the SO4?- radical, in either case. In this study, employing the pulse-radiolysis technique but adopting a new approach, these two types of reactions of the SO5?- radical have been separately quantified (at room temperature). For example, over pH 3.5-12, the branching ratio of (SO5?- + SO5?-) reactions giving rise to either the SO4?- radical or S2O82- is found to remain ～1. The respective reaction rate constants for I → 0 are (2.2 ± 0.3) and (2.1 ± 0.3) × 108 M-1 s-1. The (SO5?- + HSO3-) reactions in acid pH follow two paths, forming the SO4?- radical in one and regenerating the SO3?- radical in the other, with respective rates of ca. (6.0 ± 0.4) and (3.0 ± 0.3) × 107 M-1 s-1. In alkaline pH (for SO5?- + SO32- reactions), the rates for similar reactions are ca. (5.6 ± 0.6) and (1.0 ± 0.1) × 108 M-1 s-1. From only these results, the earlier prediction of chain length reaching a few thousands could be supported in simulation studies (Bigelow, S. L. Z. Phys. Chem. 1898, 28, 493. Young, S. W. J. Am. Chem. Soc. 1902, 24, 297. Titoff, A. Z. Phys. Chem. 1903, 45, 641. Ba?ckstro?m, H. L. J. J. Am. Chem. Soc. 1927, 49, 1460. Alyea, H. N.; Ba?ckstro?m, H. L. J. J. Am. Chem. Soc. 1929, 51, 90). To explore the feasibility of controlling S(IV) chain oxidation to sulfuric acid in liquid hydrometeors, the effect of radical scavenging on each SOx?- radical (x = 3, 4, 5) was simulated. The results show that for the SO5?- radical a scavenger reactivity of ～100 s-1 may be enough to reduce the chain length by >98%. However, in the case SO4?- radical scavenging under similar conditions, only ～75-80% reduction in acid production was observed. These results suggest a fresh modeling of sulfuric acid generation in atmospheric liquid hydrometeors.
