Premium
AUTOXIDATION OF HUMIC ACID UNDER ALKALINE CONDITIONS
Author(s) -
SWIFT R. S.,
POSNER A. M.
Publication year - 1972
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1972.tb01669.x
Subject(s) - chemistry , humic acid , fractionation , autoxidation , extraction (chemistry) , nuclear chemistry , lignin , organic chemistry , fertilizer
Summary Humic acid was treated for 30 days with normal NaOH under either N 2 or O 2 . In both cases some acid‐soluble material resulted which was enriched with free and peptide α‐amino N and also with total N. The molecular weight of the humic acid fell under alkaline conditions, while there was a decrease in total UV and visible absorption due to the production of less‐coloured material which was largely present in the acid soluble fraction. Under O 2 these effects were considerably enhanced and simultaneously a significant arnount of O 2 was consumed. Other changes produced by O 2 were an increase in the cation‐exchange capacity, particularly of the acid‐soluble fraction, the production of carbonate, an increase in the Oxidation state of the acid, and a lessening of the resemblance of the acid to lignin as shown by the infra‐red and UV spectra. In the main the changes produced by O 2 are similar to those observed for humic acids of decreasing molecular weight that can be extracted from a soil, either by differential extraction or by extraction followed by fractionation into different molecular‐weight classes.