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Fotoquímica del nitrato adsorbido
Jennifer Schuttlefield1, Gayan Rubasinghege, Mohamed El-Maazawi
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52246, USA.
Journal of the American Chemical Society
|August 30, 2008
Resumen
El nitrato en los aerosoles de polvo mineral se somete a fotólisis, produciendo óxidos de nitrógeno. El agua y el oxígeno coadsorbidos influyen en la distribución del producto, afectando la química atmosférica.
Área de la Ciencia:
- Química atmosférica La química atmosférica es la química de la atmósfera.
- La fotoquímica es la fotoquímica.
- Ciencias de la superficie Ciencias de la superficie.
Sus antecedentes:
- Los óxidos de nitrógeno reaccionan con las partículas atmosféricas, formando nitrato adsorbido.
- La fotoquímica del nitrato adsorbido superficialmente en los aerosoles es poco conocida.
- El polvo mineral y los aerosoles de sal marina son componentes clave de la atmósfera.
Objetivo del estudio:
- Investigar la fotólisis del nitrato adsorbido en la alúmina (un sustituto del polvo mineral).
- Determinar la influencia del agua coadsorbida y el oxígeno molecular en la fotoquímica de los nitratos.
- Comprender el papel de la humedad relativa en las reacciones fotoquímicas superficiales de aerosoles.
Principales métodos:
- Irradiación de alumina adsorbida por nitrato con luz de banda ancha (λ > 300 nm).
- Los experimentos se llevaron a cabo a una humedad relativa baja (<1% RH) y alta (45% RH).
- Análisis de los productos de la fase gaseosa (NO2, NO, N2O) utilizando la espectrometría de masas.
Principales resultados:
- La fotólisis de nitrato produce NO2, NO y N2O en todas las condiciones.
- El agua y el oxígeno molecular coadsorbidos alteran la distribución del producto.
- El NO es el principal producto en ausencia de O2 (seco y húmedo).
- El NO2 es el principal producto en presencia de O2.
Conclusiones:
- Este estudio es el primero en examinar el papel del agua en la fotoquímica de adsorbentes en interfaces sólidas.
- El agua, el oxígeno y la humedad relativa afectan significativamente la fotoquímica de los nitratos en las superficies de los aerosoles.
- Estos procesos fotoquímicos en los aerosoles pueden alterar el equilibrio químico de la atmósfera.
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