Date of Award
Bachelor of Arts
Juan G. Navea
Steven T. Frey
Atmospheric fly ash aerosols are byproduct of coal-fired power plants that contain bioavailable iron. Under the acidic conditions, iron will leach from fly ash particles influencing the global biological cycle. Moreover, in the presence of nitric acid, iron can reduce nitrate to nitrite, which can photodissociate to form NO and OH radicals in the atmosphere. However, quantification of aqueous nitrite formation by atmospheric aerosols is not well understood. This study reports the iron mobility and nitrite (NO2 − ) formation in fly ash from three different locations: Mid-western USA, Europe and India. In addition, the effect of two acids, HCl and HNO3, pH dependency and presence of light were investigated in this study. A proton-promoted reaction occurs in HCl, giving the maximum amount of iron dissolved in the solution. However, in HNO3 a surface-driven reaction occurs, resulting in no observation of dissolved Fe2+ . Moreover, the iron concentration is significantly smaller in HNO3 due to the direct bonding effect. In addition, nitrite concentration increases under light for well-combusted particles due to the photolytic reaction of Fe2O3. However, nitrite concentration decreases for poorlycombusted particles due to the photochemical reaction of nitrite, which reaches the steady state. Therefore, fly ash presents a potential pathway to produce NO2 − by bioavailable Fe2+ .
Xiao, Yao, "Atmospheric Processing of Combustion Particles: Iron Mobility and Nitrite Formation from Fly Ash" (2019). Chemistry Senior Theses. 3.