Nitrite photo-assisted catalytic reduction in water: mechanism and kinetic study
NO2, a toxic and potentially carcinogenic nitrogen compound, poses serious risks to water quality and human health. Although several physicochemical treatments have been developed, many convert NO2 into NH4+rather than N2(g), limiting their environmental effectiveness. This study investigates the ca...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.uam.es:10486/743040 |
| Acceso en línea: | https://hdl.handle.net/10486/743040 https://dx.doi.org/10.1016/j.seppur.2025.136491 |
| Access Level: | acceso abierto |
| Palabra clave: | Nitrite reduction Photo-assisted process Reaction mechanism Kinetic analysis iron Oxalic acid Química |
| Sumario: | NO2, a toxic and potentially carcinogenic nitrogen compound, poses serious risks to water quality and human health. Although several physicochemical treatments have been developed, many convert NO2 into NH4+rather than N2(g), limiting their environmental effectiveness. This study investigates the catalytic photo-reduction of NO2using C2O4 2 as a reducing agent and Fe3+as a homogeneous catalyst under UV irradiation. The mechanism, intermediate species, and reaction kinetics were investigated by varying the concentration of the reactants and iron species. Complete NO2 conversion was achieved within 60 min under optimized conditions, with negligible NH4+generation and transient detection of NOX gases only in the early reaction stages. Reaction mechanism follows a dual pathway, with contribution of NO2 disproportionation reactions which generate NO, NO2 and NO3. NO and NO2 can further react with H2O producing HNO2 and HNO3. On the other hand, the photo-assisted catalytic decomposition of C2O4 2 yields CO2 • radicals, which are responsible for the sequential NO2 reduction to NO•and N2O, ultimately achieving N2 (g). Kinetic analysis showed that NO3 and NO2 reduction follow an apparent pseudo-first order kinetic model, with higher apparent rate constants at lower initial NO2concentration. In contrast, C2O4 2 consumption follows a zero-order kinetic model. These findings provide mechanistic and kinetic insights into the selective photo-assisted reduction of NO2, contributing to the development of advanced water treatment strategies targeting nitrogenous contaminants |
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