Potentiometric Titration of Humic Fractions

Humic substances—humic acid, hymatomelanic acid, humus acid, and fulvic acid—have been isolated from lignite mined in the Tisulsky deposit of Kansk-Achinsk Basin. The samples obtained are characterized by means of technical and elemental analysis. The content of functional groups is determined by potentiometric titration. For all the acids, the content of carboxyl and hydroxyl groups in the humic substances may be ranked as follows: Ar–OH > Ar–COOH > Alk–COOH.