AN EXAMINATION OF THE HUMIC ACIDS OF SPHAGNUM PEAT

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Abstract
Humic acid fractions were prepared by the repeated extraction of Sphagnum peat with dilute sodium hydroxide. The infrared spectra of the initial fractions were typical of humic acids. Spectra of the later fractions were indicative of an aromatic structure similar to that of lignin. The content of methoxyl groups, which had remained constant through the earlier fractions, increased rapidly in the later fractions. Changes in the intrinsic viscosity of the fractions in aqueous alkali and salt solutions paralleled those observed in the infrared spectra and methoxyl group content. The results show that humic acids of similar composition and increasing molecular weight were extracted initially, and that low molecular weight material resembling lignin predominated towards the end of the extraction. The presence of lignin was confirmed by alkaline nitrobenzene oxidation of a peat residue. Dilute sodium pyrophosphate extracted humic acids which were similar in all respects to the first fraction obtained by extraction with dilute sodium hydroxide.

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