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Efficiency of hydroxyl radical formation and phenol decomposition using UV light emitting diodes and H2O2

Vilhunen, Sari, Puton, Jarosław, Virkutyte, Jurate, Sillanpää, Mika
Environmental technology 2011 v.32 no.8 pp. 865-872
environmental technology, hydrogen peroxide, hydroxyl radicals, phenol, ultraviolet radiation, wavelengths
A novel process combining hydrogen peroxide (H₂O₂) and radiation emitted by ultraviolet light emitting diodes (UV LEDs) has been investigated. The UV LEDs were used as UV‐C light sources emitting radiation in the range 257–277 nm for decomposition of the model substance phenol in water. In addition, the effect of H₂O₂ to phenol molar ratio and initial phenol concentration was examined. Two parameters, the decomposition efficiency of phenol and characterization of hydroxyl radical (HO•) production from H₂O₂ when illuminated with UV radiation, were selected to provide detailed information regarding the performance of the UV LEDs in the treatment process. A new concept was introduced to characterize and describe the production of HO• radicals produced when photons were absorbed by H₂O₂ molecules. The phenol decomposition efficiency at the initial concentration of 100 mg/L was the most pronounced at the lowest emitted wavelength. A significant correlation was found between the phenol decomposition efficiency and the photons absorbed by H₂O₂ (i.e. formation of radicals).