Rate constants for hydrogen abstraction reactions of the sulfate radical, SO₄⁻. Alcohols

Abstract

Rate constants have been determined for the reactions of SO4-with a series of alcohols, including hydrated formaldehyde. The SO, -radical was produced by the laserflash photolysis of persulfate, Sz02-. Rate constants for the reactions of SO4-with alcohols range from 1.0 x lo7 for methanol to 3.4 x 10' M-' s-l for 1-octanol. Rate constants for the reactions of SO4-with deuterated methanol and ethanol are lower by about a factor of 2.5. For methanol, ethanol, and 2-propanol, the temperature dependence of the rate constant was determined over the range 10-45°C.

Reactivity of selected volatile organic compounds (VOCs) toward the sulfate radical (SO4−)

“…Data concerning the reaction of CH(OH) 2 ϩ SO 4 Ϫ have been reported using apparently more or less similar experimental techniques and conditions [19,20]. These data are about a factor 2 lower than our measurement (see Table II).…”

“…It may be assumed that the observed differences of the reactivity of the sulfate radical toward the organic species considered are due to changes in the activation energies which are expected to be linked to the bond dissociation energy of the bond being ruptured [19]. If this is the case, there is a relationship between the logarithm of k H and the bond strength.…”

“…In previous studies [19,22], it was suggested that the sulfate radical reacts with alcohols, hydrocarbons, and ethers via an H-abstraction mechanism. If this is the case, we would expect the observed rate constants to be correlated with the type and bond strength of the "leaving" hydrogen atom, which is probably the one having the weakest C 9 H bond strength (it was assumed that no H-abstraction occurs at the O 9 H group for alcohols).…”

Effects of bromide on the degradation of organic contaminants with UV and Fe2+ activated persulfate

“…Any observed degradation of these compounds would therefore be resulted from radical reactions. The rate constant of t-BuOH with hydroxyl radical (k HO•/t-BuOH = 6.0 x 10 8 M -¹ s -¹ [17]) is around three-order higher than with sulfate radical (k SO4• -/ t-BuOH = 8.4 x 10 5 M -¹ s -¹ [44]). Thus, the addition of an excessive amount of t-BuOH allowed a strong suppression of the reaction of target compounds with hydroxyl radical [45][46][47].…”

Removal of carbamazepine from urban wastewater by sulfate radical oxidation

“…Quenching experiments were performed in order to identify and confirm the primary radical species produced in our system. Methanol (MeOH) and tertbutyl alcohol (t-BuOH) were selected as quenching agents since MeOH is a well-known quenching agent for both hydroxyl (k = 9.7Á10 8 M -1 s -1 ) (Buxton et al 1988) and sulfate radicals (k = 1.1Á10 7 M -1 s -1 ) (Clifton and Huie 1989), while t-BuOH reacts at a significantly higher rate with HO Á (k = 6.0Á10 8 M -1 s -1 ) (Buxton et al 1988) than with SO 4 Á-(k = 8.4Á10 5 M -1 s -1 ) (Clifton and Huie 1989). Hydroxyl radicals react with MeOH approximately 90-times faster than sulfate radicals and around 700-times faster with t-BuOH.…”