Advanced oxidation processes: mechanistic aspects.

The reactive intermediate in Advanced Oxidation Processes (AOPs) is the • OH radical. It may be generated by various approaches such as the Fenton reaction (Fe 2 +  /H 2 O 2 ), photo-Fenton reaction (Fe 3 +  /H 2 O 2 /hν), UV/H 2 O 2 , peroxone reaction (O 3 /H 2 O 2 ), O 3 /UV, O 3 /activated carbon, O 3 /dissolved organic carbon (DOC) of water matrix, ionizing radiation, vacuum UV, and ultrasound. The underlying reactions and • OH formation efficiencies are discussed. The key reactions of • OH radicals also addressed in this review.