title: Treatment of air pollution control residues with iron rich waste sulfuric acid: does it work for antimony (Sb)?
abstract: Antimony (Sb) in air pollution control (APC) residues from municipal solid waste incineration has gained increased focus due to strict Sb leaching limits set by the EU landfill directive. Here we study the chemical speciation and solubility of Sb at the APC treatment facility NOAH Langøya (Norway), where iron (Fe)-rich sulfuric acid (∼3.6M, 2.3% Fe(II)), a waste product from the industrial extraction of ilmenite, is used for neutralization. Antimony in water extracts of untreated APC residues occurred exclusively as pentavalent antimonate, even at low pH and Eh values. The Sb solubility increased substantially at pH<10, possibly due to the dissolution of ettringite (at alkaline pH) or calcium (Ca)-antimonate. Treated APC residues, stored anoxically in the laboratory, simulating the conditions at the NOAH Langøya landfill, gave rise to decreasing concentrations of Sb in porewater, occurring exclusively as Sb(V). Concentrations of Sb decreased from 87-918μgL(-1) (day 3) to 18-69μgL(-1) (day 600). We hypothesize that an initial sorption of Sb to Fe(II)-Fe(III) hydroxides (green rust) and eventually precipitation of Ca- and Fe-antimonates (tripuhyite; FeSbO4) occurred. We conclude that Fe-rich, sulfuric acid waste is efficient to immobilize Sb in APC residues from waste incineration.
authors: Department of Plant and Environmental Sciences, Norwegian University of Life Sciences (UMB), P.O. Box 5003, N-1432, Ås, Norway. gudny.okkenhaug@ngi.no
authors: Gudny
authors: G
authors: Okkenhaug
authors: Gijs D
authors: GD
authors: Breedveld
authors: Terje
authors: T
authors: Kirkeng
authors: Marit
authors: M
authors: Lægreid
authors: Trond
authors: T
authors: Mæhlum
authors: Jan
authors: J
authors: Mulder
mesh_terms: D000397:Air Pollution / Q000517:prevention & control; D000965:Antimony / Q000737:chemistry*; D007220:Industrial Waste; D007501:Iron / Q000737:chemistry*; D012995:Solubility; D013464:Sulfuric Acids / Q000737:chemistry*; D018505:Waste Management / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D013464:Sulfuric Acids; D014874:Water Pollutants, Chemical; D000965:Antimony; D007501:Iron; C033158:sulfuric acid