title: Quantifying the availability and the stability of trace cationic elements in fly ash.
abstract: For adsorption-desorption controlled leaching processes, the total leachable mass and the adsorption constant are parameters representing the availability and the stability of trace elements in solid media. With these parameters, one can predict the leaching behavior of trace elements from solids under various pH and solid-to-liquid ratio conditions. An approach was developed in this paper to determine these parameters for model elements Cu(II), Cd(II), and Ni(II) in fly ash. This approach consists of a batch equilibrium titration, a batch equilibrium leaching with and without target element addition, and mathematical modeling. Results indicated that the adsorption constant of a trace element can be determined by modeling the adsorption ratio of the added element to the system as a function of pH. Results also indicated that the trace element originally present in fly ash had similar adsorption-desorption behavior as that added externally. By modeling the batch leaching data with and without external element addition, the total leachable mass and adsorption constant of the target element can be determined simultaneously. The total leachable mass is in agreement with experimental data from 50mM EDTA extraction.
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, University of Missouri--Rolla, Rolla, MO 65409, USA.
authors.forename: Tian
authors.initials: T
authors.lastname: Wang
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wang
authors.forename: Heng
authors.initials: H
authors.lastname: Ban
authors.forename: Ken
authors.initials: K
authors.lastname: Ladwig
mesh_terms: D002104:Cadmium / Q000032:analysis / Q000737:chemistry; D002244:Carbon / Q000032:analysis* / Q000737:chemistry; D002412:Cations; D060729:Coal Ash; D003300:Copper / Q000032:analysis / Q000737:chemistry; D004782:Environmental Health; D004784:Environmental Monitoring / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009532:Nickel / Q000032:analysis / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry; D014131:Trace Elements / Q000032:analysis* / Q000737:chemistry
chemical_list: D002412:Cations; D060729:Coal Ash; D052638:Particulate Matter; D014131:Trace Elements; D002104:Cadmium; D002244:Carbon; D003300:Copper; D009532:Nickel