Hydroxyl radical

Quantum mechanics

Catalysis

Ultraviolet

Engineering

Photochemistry

Materials science

Hydrogen peroxide

Inorganic chemistry

Chemical engineering

Ammonium hydroxide

Hydroxide

Physics

Organic chemistry

X-ray photoelectron spectroscopy

Radical

Ozonide

Kinetics

Chemistry

Advanced oxidation process

Optoelectronics

Chlorine

Ozone

Chlorine dioxide

Journal of Hazardous Materials

The key step for nitric oxide (NO) removal using oxidation method is to efficiently oxidize NO. This study developed a novel advanced oxidation process (AOP) of ultraviolet light (UV) catalysis of chlorite (NaClO2) to oxidize NO. The production of nitric dioxide (NO2) and photo-production of chlorine dioxide (ClO2) were suppressed by adding ammonium hydroxide (NH4OH). The NO conversion efficiency was 98.1% using UV/NaClO2-NH4OH. Electron spin resonance (ESR) tests confirmed the roles of hydroxyl radical (HO) and oxychloride radical (ClO/Cl2O2) in the oxidation of NO. Kinetics analyses showed that NO flux was significantly enhanced by radical-induced (HO/ClO) oxidation of NO. In the presence of UV, the overall reaction rates (kov1*) were 3-8 times higher than those without UV. The Hatta number, namely the enhanced factor, was calculated in the range of 229-403 and 730-780 corresponding to without and with UV light, suggesting that NO oxidation belonged to fast and/or instantaneous reaction. Thus, the gas-film mass transfer resistance was the rate-determining step. N-containing product was determined as NH4+ and NO3- according to X-ray photoelectron spectroscopy (XPS).

A novel method of ultraviolet/NaClO2-NH4OH for NO removal: Mechanism and kinetics