Fly ash, an iron-containing byproduct of coal-fired power plants, is commonly found in atmospheric aerosol plumes. Induced by proton-promoted dissolution in acidic atmospheric water, these particles leach both Fe (II) and Fe (III).  This iron dissolution can impact the chemical balance of the atmosphere and prompts carbon sequestration in the open ocean by inducing to phytoplankton blooms.  These environmental effects can vary at daytime, as solar radiation can interact with the semiconductor and/or chromophores components of fly ash. In addition, solar radiation can impact redox reactions on iron oxides, changing the yield and/or rate of iron leach.In this work, we report the yield and initial rate of iron leached from fly ash from different source regions. Three fly ash samples were examined under atmospherically relevant pHs along with simulated solar radiation: US Midwest, Northeast India, and European ash. In general, simulated solar radiation tends increase the initial rate of iron dissolution. This change in rates was found to be larger in fly ash suspension in pH 2 solutions than that at pH 1. In addition, while Fe (III) is the dominant speciation of dissolved iron from all fly ash samples, solar radiation has been found to increase the fraction of aqueous Fe (II) up to three times the values measured in the absence of solar radiation.

Effect of simulated solar radiation on the leach of iron from fly ash from various source regions

251st National Meeting (2016)

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