Leaching kinetics of bottom ash waste as a source of calcium ions
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Taylor & Francis
Abstract
Bottom ash is a waste material from coal-fired power plants, and it is known to contain elements that are potentially toxic at
high concentration levels when disposed in landfills. This study investigates the use of bottom ash as a partial substitute sorbent
for wet flue gas desulfurization (FGD) processes by focusing on its leaching kinetics in adipic acid. This was studied basing on
the shrinking core model that was applied to the experimental data obtained by the authors presented at the International
Conference on Industrial, Manufacturing, Automation and Mechanical Engineering, Johannesburg, South Africa, November
27–28, 2013) on dissolution of bottom ash. The leaching rate constant was obtained from different reaction variables, namely,
temperature, pH, acid concentration, and solid-to-liquid ratio, that could affect the leaching process. The solid sample of bottom
ash was characterized at different leaching periods using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It
was found that solid-to-liquid ratio had a significant effect on the leaching rate constant when compared with other variables.
The leaching kinetics showed that diffusion through the product layer was the rate-controlling step during leaching, and the
activation energy for the process was found to be 18.92 kJ/mol
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Koech, L. et al. 2015. Leaching kinetics of bottom ash waste as a source of calcium ions. Journal of the Air & Waste Management Association, 65(2):126-132. [https://doi.org/10.1080/10962247.2014.978958]