Ultraviolet light emitting diodes and hydrogen peroxide in the photodegradation of aqueous phenol

The novel system of ultraviolet (UV) light emitting diodes (LED) and hydrogen peroxide (H₂O₂) was studied for the degradation of phenol as a model organic pollutant in water. The effect of different viewing angles (15 and 120°), wavelengths (255, 265 and 280 nm) and phenol and H₂O₂ concentrations were investigated in four photolytic batch reactors. Phenol degradation was observed to be most efficient with UV LEDs emitting at wavelength 280 nm, presumably due to the highest optical power. However, quantum yield for 280 nm reactor was only 0.23 compared to 0.33 of 255 nm reactor. Quantum yields for the rest of the reactors were 0.24 (265 nm, 120°) and 0.22 (265 nm, 15°). UV LEDs in combination with hydrogen peroxide are promising in wastewater treatment in degrading organic compounds, though development of both LEDs and reactor design is needed.