Adsorptivity And Its Geological-Geochemical Controls Of Humic Acid From Lignite

Humic acid is an important component of lignite.Its macromolecular structure is loose,has many surface active groups and unique adsorption-desorption characteristics.However,little is known about the adsorption desorption behavior of humic acid in lignite and its effect on gas storage capacity of lignite reservoir.In view of this,the author extracted humic acid from lignite in Hailaer basin,comparatively analyzed the chemical structure and pore structure of lignite and humic acid,revealed the adsorption and desorption behavior of humic acid and its influence on the adsorptivity of lignite,and explained its geological geochemical control mechanism.The results show that the hydroxyl absorption band of lignite is dominated by hydroxyl cyclic polymer,hydroxyl of humic acid mainly exists in the form of hydroxyl ether hydrogen bond,followed by hydroxyl cyclic polymer.The aliphatic hydrocarbons of lignite and humic acid mainly exist in the form of long chain,less branched chain and trisubstituted benzene ring.The humic acid is high in aromatic carbon ratio and isomerization degree of fat side chain,and its aromatic carbon is mostly bonded with carboxyl group.The aromatic carbon of lignite mainly exists in the form of aromatic ring covalent bond carbon atom.At the same time,the pore structure of lignite is dominated by mesopores,while that of humic acid is dominated by macropores and mesopores,and their specific surface areas are mainly controlled by micropores and transition pores;most of lignite pores are semi-closed pores,while most of humic acid pores are inkbottle-like pores,cylinder pores and parallel plate pores.Comprehensive analysis shows that strong humification is conducive to the formation of primary humic acid and improves the adsorption capacity of lignite.The specific surface area is the main factor controlling the adsorptivity of lignite,and other factors indirectly affect the adsorptivity of lignite through controlling pore specific surface area and humic acid characteristics.The paper includes 41 illustrations,24 tables and 158 references.