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Leaching Tests of Heavy Metals Stabilized with Portland Cement
William Shively, Paul Bishop, David Gress and Todd Brown
Journal (Water Pollution Control Federation)
Vol. 58, No. 3 (Mar., 1986), pp. 234-241
Published by: Water Environment Federation
Stable URL: http://www.jstor.org/stable/25042886
Page Count: 8
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Release of four heavy metals from a cement matrix was studied during 15 sequential extractions with dilute acetic acid. Two types of metal binding occurred. Adsorption-precipitation limited cationic metal solubility at high pH. Metal anions were leached at high pH during the first three extractions, but with little degradation of the cement matrix. Leachate pH decreased from > 10.0 to < 6.0 in the next three extractions, and cationic metals were released in increasing concentrations. Heavy metal releases were limited as the pH decreased steadily to 4.0 in the subsequent extractions. This second binding process involved chemical changes of the silicate matrix. Heavy metals remained in the silica-rich particles after the extractions. Alkalinity was from calcium hydroxide in the cement paste, and the dry material contained an average buffering capacity of 18.3 meq/g.
Journal (Water Pollution Control Federation) © 1986 Water Environment Federation