Particle size and morphology have important consequences for tropospheric aerosol dissolution. For instance, smaller particles have a larger contact area with the atmospheric acid media. In addition, spherical particles tend to have a higher exposed surface, increasing its solubility. Therefore particle morphology is expected to impact proton-promoted dissolution of iron in particles like fly ash, iron-containing particles produced in coal-fired power plants. These particles are often found in tropospheric aerosol events; because fly ash consist on highly spherical particles, they have a large transport, long atmospheric residence time, and a large surface area exposed to the atmospheric acidic water. A Brunauer-Emmet-Teller surface area was compared to the sphericity of the particles, allowing for a comparative assessment of the effects of surface defects on the leach of iron from fly ash under atmospherically relevant conditions. The leach of iron and its oxidation state was investigated from three well-characterized fly ash particles: US, Indian, and European fly ashes. Surface defect was found to correlate well with the initial rate of iron dissolution, although surface composition plays an important role in the acid-surface interaction. Overall, particle size and mineralogy, along with the combustion efficiency, played an important role in both the solubility of total iron and the iron speciation in solution.

Fly ash size and particle defects: A morphological study on proton-promoted iron leach from fly ash

251st National Meeting (2016)

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