Title: Humic Acids
Literature References: Allomelanins found in soils, coals, and peat, resulting from the decompn of organic matter, particularly dead plants. Consists of a mixture of complex macromolecules having polymeric phenolic structures with the ability to chelate with metals, esp iron. Review: R. A. Nicolaus, Melanins (Hermann, Paris, 1968) pp 147-153; W. Flaig et al. in Soil Components vol. 1, J. E. Gieseking, Ed. (Springer, New York, 1975) pp 1-211.
Properties: Chocolate-brown, dust-like powder. Slightly sol in water, usually with much swelling; sol in alkali hydroxides and carbonates; also sol in hot concd HNO3 with dark-red color.
Use: In mud baths, drilling muds, pigments for printing inks, fertilizers, growth hormones for plants, transporters of trace minerals in soil: Steelnick, J. Chem. Educ. 40, 379 (1963). |