Combustion particles are commonly found in atmospheric aerosol plumes, where long transport takes them through various relative humidity regions. Particles like fly ash, produced during the combustion of coal in power plants, are found in isolated atmospheric regions, away from their power plant source. Given their long transport and residence time, fly ash particles can impact atmospheric physical and chemical processes. For instance, depending on their hygroscopic properties, fly ash particles can act as cloud condensation nuclei (CCN). These CCN properties are closely dependent on both the coal minerology and the combustion process efficiency. In this work, we examine the water uptake isotherms of fly ash samples from several source regions: US fly ash, Indian fly ash, and European fly ash. Fly ash composition and morphology was examined for each sample and the formation of water monolayers was studied using a quartz crystal microbalance inside a variable relative humidity chamber. In addition, changes in infrared features are also discussed as a function of the water uptake capacity. In general, a water multilayer is formed on the fly ash particles as a relative humidity increases in the chamber. The adsorption/desorption isotherms show that water tends to remain adsorbed onto the surface of fly ash particles, suggesting that the uptake of water on these bulk samples can lead to CCN properties.

Study of water adsorption/desorption isotherms on several fly ash sources

251st National Meeting (2016)

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