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Structural Study of Humic Acids by X‐ray, Electron Spin Resonance, and Infrared Spectroscopy
Author(s) -
Eltantawy I. M.,
Baverez M.
Publication year - 1978
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/sssaj1978.03615995004200060014x
Subject(s) - chemistry , humic acid , electron paramagnetic resonance , infrared spectroscopy , carbon fibers , spectroscopy , radical , compost , infrared , carbon black , organic chemistry , nuclear magnetic resonance , materials science , fertilizer , physics , optics , ecology , natural rubber , quantum mechanics , composite number , composite material , biology
Composts and soil humic acid structures were examined by X‐ray, ESR, and IR methods. X‐ray diffraction showed three bands at 3.6, 2.1, and 1.2Å for the studied humic acids. These bands occured on the same position as the (002), (10), and (11) of carbon black and were ascribed to aromatic structure or graphite‐like layers. The presence of a 7.5Å band in the X‐ray diffraction of the examined humic acids indicate to nonaromatic fraction too. IR spectra confirm the presence of aromatic and aliphatic fractions associated with various types of functional groups including quinone groups. The nature of these groups are discussed. ESR signal G ∼ 2 indicates the presence of free radicals within the humic substances, whereas very little is known about the ESR signal at G ∼ 4.125 observed in the studied humic acids. This signal was attributed to Fe 3+ chelated to humic substances. Compost and soil humic acids showed some structural differences.