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Sorption of cadmium and lead by clays from municipal incinerator ash- water suspensions

January 1, 1993

The effect of Cl complexation in extracts of a flue gas-scrubber incinerator fly ash sample on the sorption of Cd and Pb by kaolinite and illite was investigated using batch-sorption methods. In the pH range of 5 to 9, Cl complexation may reduce sorption and thus increase the mobility of these metals. When an ash—water suspension was acidified to pH 6.85, the dissolution of Cl and Ca essentially eliminated Cd sorption because of complexation and cationic competition. Cadmium would be considered as either mobile or very mobile under these conditions. Lead was not soluble in the pH-6.85 suspension. At pH 12, the approximate pH of water in contact with flue gas-scrubber fly ash, Cd was essentially insoluble and Pb occurred as anionic Pb hydroxide. Anionic Pb was sorbed by the two clays, and the extent of sorption was not influenced by Cl or carbonate complexation. Sorption constants, derived from isotherms, suggested that Pb would be relatively immobile in saturated soil—water systems. The recent concern that highly alkaline, flue gas-scrubber fly ash may release environmentally significant concentrations of mobile Pb when placed in an ash-disposal site with a soil liner should be reevaluated in light of this study.

Publication Year 1993
Title Sorption of cadmium and lead by clays from municipal incinerator ash- water suspensions
DOI 10.2134/jeq1993.00472425002200030019x
Authors W. R. Roy, I.G. Krapac, J.D. Steele
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Environmental Quality
Index ID 70018351
Record Source USGS Publications Warehouse