Bicarbonate Effect in the Ozone-UV Process in the Presence of Nitrate

Abstract

Ozonation and advanced oxidation processes (AOP) are very efficient methods for the destruction of refractory organic matters. These virtues have always been related to the production of hydroxyl radicals HO•, which are extremely powerful and non-selective oxidants. In this study, the O3-UV process is used as an AOP, where hydroxyl radicals are generated from the photodecomposition of ozone by short wavelength ultraviolet radiation. The obtained results indicated a weak scavenging effect of tert-butanol proving that hydroxyl radicals and ozone are not the only oxidants existing in the medium. Moreover, bicarbonate, known for a long time as effective HO• radical scavengers, does not slow down the oxidation of benzoic acid, but surprisingly increases it. Chlorides significantly decrease the degradation of organic compounds through their reaction with HO• radicals to produce chlorine. Carbonate radicals, nitrate and nitrogenated species as peroxynitrite/ peroxynitrous acid are involved in the oxidative mechanisms.