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Use of Chelating Resins in Metal Adsorption Studies
Author(s) -
Turner M. A.,
Hendrickson L. L.,
Corey R. B.
Publication year - 1984
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1984.03615995004800040013x
Subject(s) - adsorption , ionic strength , metal , chemistry , metal ions in aqueous solution , chelation , trace metal , atomic absorption spectroscopy , ionic bonding , inorganic chemistry , absorption (acoustics) , stability constants of complexes , ion , materials science , organic chemistry , aqueous solution , composite material , physics , quantum mechanics
Metal adsorption characteristics obtained using conventional batch equilibration methods are often of limited use for predicting the behavior of trace metals under natural conditions due to inadequate control of the composition and pH of the equilibrium solution. Much of the existing adsorption data has also been obtained using unrealistically high metal concentrations and in response to total soluble metals rather than unassociated metal ions. These limitations were overcome via the use of chelating resin to establish and maintain constant pH and metal activity in a solution of constant ionic strength and composition. The Cd/Ca ratio of the resin was varied to provide a range of Cd activities (0–1.5 µ M ) consistent with normal soil solution concentrations when equilibrated with 0.01 M Ca(NO 3 ) 2 . A series of these prepared resin systems were equilibrated with an Fe gel, a muck, and an intact soil to obtain Cd adsorption data in response to Cd activities as low as 10 −8 M . These resin systems can also be used to describe metal adsorption as a function of ionic metal concentrations in systems containing soluble complexing agents. The resins can provide ionic metal concentrations below the sensitivity of flameless atomic absorption spectrophotometry, and the activity of several trace metals can be maintained by the same resin, thus enabling evaluation of metal competition for adsorption sites. In some cases, the resin system may eliminate the requirement for a complete adsorption isotherm, since metal adsorption can be determined in response to one or more predetermined metal activities.