Copper and Cadmium Adsorption Characteristics of Selected Acid and Calcareous Soils1
- N. Cavallaro and
- M. B. McBride2
Samples of two New York soils, an acid and a neutral silt loam, were equilibrated with Cu2+ and Cd2+ solutions in concentrations ranging from 10−5 to 10−4M in distilled water and in 0.01M CaCl2. The extent of complexation and adsorption of the heavy metals was measured using specific ion electrodes and atomic absorption. The data were found to fit the Langmuir adsorption model, and the Cu2+ adsorption maxima were greater than those of Cd2+ for both soils. Acid soils demonstrated much less ability to retain the heavy metals than neutral soils. In the presence of 0.01M CaCl2, adsorption of the metals was much reduced, suggesting Ca2+ competition for adsorption sites. A considerable amount of Cu2+ was complexed in the soil solutions, but Cd2+ complexation was much less evident. The results support an ion exchange mechanism of adsorption in the surface soils, and suggest that precipitation occurs in calcareous subsoils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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