Preparation and Characterization of CaO/CaSO4/Coal Fly Ash Sorbent for Sulfur Dioxide (SO2) Removal: Part I

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Abstract
A 2 level full factorial design of experiment was used to evaluate the significance of four sorbent preparation variables towards the structural properties of sorbent prepared from coal fly ash, calcium oxide (CaO) and calcium sulfate (CaSO4) for flue gas desulfurization. The structural properties studied were BET specific surface area and average pore size of the sorbent while the experimental sorbent preparation variables studied were hydration period (x 1), ratio of CaO to fly ash (x 2), amount of CaSO4 (x 3), and drying temperature (x 4). The surface area and average pore diameter of the sorbent obtained in this work range from 12.9 to 92.7 m2/g and 48.4 to 159.5 nm, respectively. The results revealed that there were significant influence of all the variables studied on the average pore diameter of the sorbent while only variables x 1, x 2, and x 3 had significant influence on the surface area of the sorbent. X-ray diffraction (XRD) analysis revealed that the main phases detected in the sorbent was calcium alumino silicate hydrate compound. Scanning electron microscope (SEM) analysis showed that the sorbent consists of irregular shape particles that have a high structural porosity.