THE COMPOSITION OF LIGNITE HUMIC ACIDS

Humic acids from lignite deposits in Bulgaria were characterized with respect to the concentration of oxygen-containing functional groups. T he following ranges were determined, in mequiv g-1: total acidity 5.1- 6.8; carboxylic groups 3.5-4.5; phenolic OH groups 1.6-2.3; ketone gro ups 4.0-2.0; quinone groups 1.0-1.3; and methoxyl groups 0.3-1.3. Yiel ds of high- and low-molecular fractions were monitored by g.p.c. on Se phadex G-50. The molecular mass for the lower molecular fraction was a pproximately 4000 u. On the basis of the elemental composition, molecu lar mass and distribution of oxygen in functional groups, a concept fo r lignite humic acid structure was developed.