Contrasting radical activity

Reaction intermediates formed during the ultra-violet (UV) activation of hydrogen peroxide (H2O2) (UV-AHP) and persulfate (S2O82-) (UV-APS) include hydroxyl (•OH) and sulfate radicals (SO4•-), respectively. These radicals, used in oxidation treatment systems to degrade a broad spectrum of environmental contaminants, may also react with non-target chemical species (scavengers) that limit treatment efficiency. UV-AHP and UV-APS treatment systems were amended with solid phase alumina to assess scavenging by solid surfaces. The relative rates of reaction between the target compound, rhodamine B dye (RhB), and aqueous and solid phase scavengers was used to assess treatment performance. The overall rate of reaction and rate of radical scavenging was greater for •OH than SO4•-. Scavenging by dissolved constituents was dominated by the oxidant used (H2O2, S2O82-); and the rate of radical scavenging by alumina was greater than the rate of RhB oxidation in all cases. Treatment efficiency was lower in the UV-AHP than in the UV-APS treatment system and was attributed to greater aqueous and solid phase scavenging rates. The cost of commercially available H2O2 ($0.031 mol-1) and PS ($0.24 mol-1) was used in conjunction with the overall treatment efficiency to assess specific cost of treatment. The specific cost to treat the probe compound with UV-AHP was greater than UV-APS and was attributed to the much lower treatment efficiency with UV-AHP. The much-desired high reaction rate constants between •OH and environmental contaminants, relative to SO4•-, comes at the cost of greater combined scavenging rates, and consequently lower treatment efficiency.

This dataset is associated with the following publication: Rusevova Crincoli, K., and S.G. Huling. Contrasting hydrogen peroxide- and persulfate-driven oxidation systems: Impact of radical scavenging on treatment efficiency and cost. Chemical Engineering Journal. Elsevier BV, AMSTERDAM, NETHERLANDS, 404: 1-6, (2021).