Composition of Humic and Fulvic Acids from Lignite
K. S. Votolin, С. И. Жеребцов, K. M. Shpakodraev, Н. В. Малышенко, З. Р. Исмагилов
Abstract
A method has been developed and tested for isolating humic acids and fulvic acids from lignite. The yields are high: up to 68.0% for humic acids; and up to 9.6% for fulvic acids. The composition of the initial and residual lignite from the Kansk-Achinsk and South Ural Basins and the extracted humic and fulvic acids is investigated by technical analysis, elemental analysis, FTIR spectroscopy, and 13C NMR (CPMAS) spectroscopy. The humic acids and fulvic acids from lignite differ in chemical and structural composition. The fulvic acids are characterized by higher content of oxygen-bearing aliphatic groups, with a predominance of carbonic acids and complex esters, as confirmed by their highly hydrophilic behavior. The humic acids are characterized by higher content of carbon, hydrogen, and aromatic fragments. That must be taken into account in their practical use.