title: An assessment of Mercury immobilisation in alkali activated fly ash (AAFA) cements.
abstract: This paper presents total and soluble Mercury contents for three coal fly ashes and alkali-activated fly ash (AAFA) cements consisting of 100% fly ash as starting material. To evaluate the potential of the AAFA cement matrix to immobilise Hg from an external source, another batch of cements, doped with 5000 mg/kg Hg as highly soluble HgCl(2), was prepared. The ashes and control AAFA cements complied with Mercury leaching criteria for non-hazardous wastes according to both TCLP and EN 12457 tests. Fly ash activated cements doped with 5000 mg/kg Hg and aged for 2 days immobilised 98.8-99.6% and 97.3-98.8% of Hg according to TCLP and EN 12457 tests respectively. Evidence from SEM-EDX suggests that Hg was immobilised by precipitation as highly insoluble HgS or Hg(2)S, although partial precipitation as less insoluble HgO or Hg silicates could not be entirely ruled out based on data presented. The results for Hg-doped cements contribute to the growing body of evidence that shows AAFA cement as a useful material for immobilizing elevated concentrations of toxic and hazardous elements.
authors.affiliation: Eduardo Torroja Institute of Construction Sciences (CSIC), Calle Serrano Galvache, 4 Madrid, 28033 España, Spain. shanedonatello@ietcc.csic.es
authors.forename: Shane
authors.initials: S
authors.lastname: Donatello
authors.forename: Ana
authors.initials: A
authors.lastname: Fernández-Jiménez
authors.forename: Angel
authors.initials: A
authors.lastname: Palomo
mesh_terms: D000465:Algorithms; D000468:Alkalies; D060729:Coal Ash / Q000737:chemistry*; D003252:Construction Materials / Q000032:analysis*; D008628:Mercury / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D012995:Solubility; D013052:Spectrometry, X-Ray Emission; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000468:Alkalies; D060729:Coal Ash; D008628:Mercury