Preparation of Fe and Ca Enriched Sorbents Derived from Coal Fly Ash for Arsenic Capture from Flue Gas

Fly ash has been regarded as a potential sorbent for capturing trace elements from flue gas due to its high concentrations of Ca and Fe components. In this paper, a low-cost sorbent for capturing arsenic was prepared by gravity separating coal fly ash. When bromoform was used as the solution for separating the high-sulfur fly ash, Ca, S, and Fe contents in the heavy fly ash (A3) were 24.02, 19.11, and 12.8%, while those of the raw fly ash (A1) were 8.06, 8.97, and 7.63%, respectively. Due to the enrichment of Ca and Fe, the arsenic capturing capacity of the fly ash sorbents under 700 degrees C was increased from 626 (A1) to 702 mu g/g (A3). When the flue gas contained 1500 ppm SO2, the arsenic adsorption capacity of A3 further promoted to 759 mu g/g. Meanwhile, it was found that over 48% arsenic existed as As(V) in the used sorbent (A3). XPS spectra also proved that there was an interaction of Ca or Fe and arsenic, which was attributed to arsenic removal from the flue gas.