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- Title
Removal of Heavy Metals from Soil Components and Soil by Natural Chelating Agents. Part I: Displacement from Clay Minerals and Peat by L-Cysteine and L-Penicillamine.
- Authors
Fischer, K.
- Abstract
The β-thiol group containing amino acids L-cysteine and L-penicillamine were tested for their ability to release heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) from bondings onto typical soil components (peat, bentonite, illite) at neutral pH formed by batch adsorption procedure. Following equilibration the metal loaded sorbents were extracted by aqueous amino acid solutions under various physico-chemical conditions. The extractability of metals from peat (metal contents between 62.0 and 6170 mg kg-1) increased in the presence of L-penicillamine following the order Cr < Hg < Pb < Ni ≈ Zn ≈ Cd, ranging from 9% (Cr) to 97% (Cd). The extractability by L-cysteine was slightly lower, following the sequence Cr < Pb < Cd < Ni < Zn. In both cases the sequences did not correlate with the order of the stability constants of the corresponding amino acid complexes. The recovery of metals from bentonite was higher generally. The extent of removal increased with increasing molar excess of the amino acids and, to a lower extent, with increasing extraction volume. Presumably initiated by oxidation of amino acids or by the formation of sparingly soluble polymeric metal complexes, the concentrations of dissolved metals dropped after an agitation period of 2 to 24 hr in most of the extracts. Aspects of this process were discussed in detail.
- Subjects
HEAVY metals; SOILS; CLAY minerals; PEAT; PENICILLAMINE; ANTIARTHRITIC agents
- Publication
Water, Air & Soil Pollution, 2002, Vol 137, Issue 1-4, p267
- ISSN
0049-6979
- Publication type
Article
- DOI
10.1023/A:1015547323779