Selective oxidation of ammonium to dinitrogen by a novel catalytic ozonation system: Regulating the N2 selectivity by
Yuexinxi Wang1, Yong Liu1, Shizong Wang2
1College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, PR China.
Abstract:
The selective oxidation of NH4+-N into dinitrogen (N2) is still a challenge. Currently, traditional advanced oxidation processes often involve in the chlorine free radicals to increase the selectivity of NH4+-N oxidation products towards N2 but is usually accompanied by the production of many toxic disinfection by-product. Herein, we reported a novel catalytic ozonation system (UV/O3/MgO/Na2SO3) for selective NH4+-N oxidation based on the reducing capability and photochemical properties of Na2SO3. In the UV/O3/MgO/Na2SO3/NH4+-N system, Na2SO3 could not only reduce the intermediate of NO2- or NO3- to N2 by inducing the generation of hydrated electrons under UV irradiation, but also reduce the gaseous intermediate of NOx to N2, thus achieving a high N2 selectivity (>85 %). Based on the analyses of each component roles, the determination of reactive oxygen species and the evolution of NH4+-N oxidation intermediates, the possible mechanisms of NH4+-N selective oxidation by UV/O3/MgO/Na2SO3 system were revealed. This system exhibits a great potential for the NH4+-N removal from water/wastewater. This work provides a new strategy for NH4+-N oxidation into N2 by advanced oxidation processes independent of the action of chlorine free radicals.
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