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The Metal Complexing Capacity and the Nature of the Chelating Ligands of Water Extract of Poultry Litter
Author(s) -
Tan K. H.,
Leonard R. A.,
Bertrand A. R.,
Wilkinson S. R.
Publication year - 1971
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/sssaj1971.03615995003500020026x
Subject(s) - chemistry , chelation , divalent , dissolution , metal , aqueous solution , organic matter , inorganic chemistry , solubility , metal ions in aqueous solution , nuclear chemistry , organic chemistry
The metal complexing capacity and the nature of the chelating ligands of organic matter extracted from broiler house litter were studied by ion‐exchange equilibrium and dissolution methods and infrared spectroscopy. The water extract of broiler house litter appeared to exhibit a significant chelating effect on the cations Cu 2+ , Zn 2+ , Mg 2+ , and Al 3+ . The amount of organic matter complexed by one mole of metal and the stability of metal complexes increased with increasing pH in the cases of Cu‐, Mg‐, and Al‐complexes, but were unaffected by changes in pH in the case of Zn‐complexes. With respect to the divalent ions, the amount of organic matter chelated and the stability of the divalent metal‐complexes decreased in the order Cu > Zn > Mg. Dissolution studies with insoluble Al 2 O 3 and Fe 2 O 3 powders showed that both Al and Fe were chelated in the aqueous extract, but 10 times more Al than Fe was dissolved in a given time period. Infrared analysis revealed spectrograms of the ligands similar to those obtained for polysaccharides. However, since the freeze‐dried extract contained 9% N, some NH 2 groups must have been present, although bands of these groups were not resolved from overlapping O‐H bands. Functional group frequency vibration comparisons at 3,500, 3,200, 1,650, and 1,400 cm ‐1 showed that the formation of stable metal‐complexes involved carboxyl electrovalent linkages and probably hydroxyl and/or amino coordinate linkages.