Interaction between the bituminous and humic components of peat

Abstract

It was established that an increase in the bituminosity of peat with the degree of decomposition can be explained by an exchange interaction between the π electrons of the molecular polyconjugation systems of humic acids and the quasi-polyconjugation systems of bitumens (the presence of the latter is caused by a synergistic effect of the interaction of separated aromatic rings and the hydrogen bonds of functional groups). This interaction leads to the formation of unique associates, and this fact explains an increase in the concentration of humic substances in a composition with bitumens with increasing the degree of decomposition. The concept of associates is confirmed by a considerable increase in the EPR signal observed upon the removal of a low bitumen content, which was accompanied by changes in its parameters in a number of cases. The formation of these associates occurs under different geoclimatic conditions of peat deposit formation. The lower bituminosity of lowland peats is caused by steric hindrances created by the Ca²⁺ ions bound to the functional groups of humic substances for the access of hydrocarbon molecules.