Acid-base characterization of molecular weight fractionated humic acid

Acid-base properties of molecular weight fractionated humic acids (HAs) were investigated by the acid-base potentiometric titration. The acidic group contents ( C A t ) and the average values of apparent p K (p K app) were evaluated by applying a modified Henderson-Hasselbalch equation to the experi...

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Published inTalanta (Oxford) Vol. 43; no. 3; pp. 383 - 390
Main Authors Fukushima, Masami, Tanaka, Shunitz, Nakamura, Hiroshi, Ito, Saburo
Format Journal Article
LanguageEnglish
Published Netherlands Elsevier B.V 01.03.1996
Subjects
Acid-base properties
Aromaticity
Humic acids
Aromaticity
Humic acids
Acid-base properties
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Summary:Acid-base properties of molecular weight fractionated humic acids (HAs) were investigated by the acid-base potentiometric titration. The acidic group contents ( C A t ) and the average values of apparent p K (p K app) were evaluated by applying a modified Henderson-Hasselbalch equation to the experimental titration curves. The average values of p K app of the fractionated and unfractionated HAs were about 4.1–4.4, and the distribution of p K app values could be represented by the relationships between α and p K app plots in the range 2–8. The C A t values increased with a decrease in molecular size, as did the aromaticity. This suggests that the acidic group contents are related to the aromaticity of the HA.
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ISSN:0039-9140
1873-3573
DOI:10.1016/0039-9140(95)01727-5