title: Leaching characteristics of toxic constituents from coal fly ash mixed soils under the influence of pH.
abstract: Leaching behaviors of Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Magnesium (Mg), Selenium (Se), and Strontium (Sr) from soil alone, coal fly ash alone, and soil-coal fly ash mixtures, were studied at a pH range of 2-14 via pH-dependent leaching tests. Seven different types of soils and coal fly ashes were tested. Results of this study indicated that Ca, Cd, Mg, and Sr showed cationic leaching pattern while As and Se generally follows an oxyanionic leaching pattern. On the other hand, leaching of Ba presented amphoteric-like leaching pattern but less pH-dependent. In spite of different types and composition of soil and coal fly ash investigated, the study reveals the similarity in leaching behavior as a function of pH for a given element from soil, coal fly ash, and soil-coal fly ash mixtures. The similarity is most likely due to similar controlling mechanisms (e.g., solubility, sorption, and solid-solution formation) and similar controlling factors (e.g., leachate pH and redox conditions). This offers the opportunity to transfer knowledge of coal fly ash that has been extensively characterized and studied to soil stabilized with coal fly ash. It is speculated that unburned carbon in off-specification coal fly ashes may provide sorption sites for Cd resulting in a reduction in concentration of these elements in leachate from soil-coal fly ash mixture. Class C fly ash provides sufficient CaO to initiate the pozzolanic reaction yielding hydrated cement products that oxyanions, including As and Se, can be incorporated into.
authors.affiliation: Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706, United States.
authors.forename: Kanokwan
authors.initials: K
authors.lastname: Komonweeraket
authors.affiliation: College of Engineering, University of Georgia, Athens, GA 30602, United States. Electronic address: bora.cetin@sdsmt.edu.
authors.forename: Bora
authors.initials: B
authors.lastname: Cetin
authors.affiliation: Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706, United States. Electronic address: chbenson@wisc.edu.
authors.forename: Craig H
authors.initials: CH
authors.lastname: Benson
authors.affiliation: Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, United States. Electronic address: aydilek@umd.edu.
authors.forename: Ahmet H
authors.initials: AH
authors.lastname: Aydilek
authors.affiliation: Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706, United States. Electronic address: edil@engr.wisc.edu.
authors.forename: Tuncer B
authors.initials: TB
authors.lastname: Edil
mesh_terms: D001151:Arsenic / Q000032:analysis; D002104:Cadmium / Q000032:analysis; D060729:Coal Ash / Q000737:chemistry*; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D008396:Maryland; D008673:Metals, Alkaline Earth / Q000032:analysis; D008910:Minnesota; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry*; D012995:Solubility; D014922:Wisconsin
chemical_list: D060729:Coal Ash; D008673:Metals, Alkaline Earth; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D001151:Arsenic
keywords: C-type fly ash; High carbon fly ash; Metals; Minerals; Sulfate; pH-dependent leaching test