Physicochemical characteristics of coals with different ranks in geothermal water environments
GE Peng
Abstract：To elucidate the structural evolution and interfacial reactivity of coals with different metamorphic degrees under geothermal conditions,three representative coal samples,gas coal(GC),coking coal(CC)and anthracite(ANT),were subjected to water-coal interaction experiments at 25℃and 50℃.Scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and contact angle measurements were employed to systematically characterize variations in surface morphology,functional groups,and hydrophilicity.The results showed that geothermal treatment markedly facilitated the transformation of coal sur-faces from compact to porous structures,with more pronounced pore development and crack propagation in low-rank coals.With the increase of temperature,the content of polar functional groups such as C—O and C＝O increases,the proportion of C—C structure decreases,the O/C ratio has significantly increased,it indicates that the coupled heat-water effect enhances the oxidation and polarization processes on the coal surface.Contact angle measurements further revealed that coal hydrophilicity was significantly enhanced with temperature,particularly for coking and an-thracite coals,indicating that geothermal conditions strengthen water-coal interfacial reactions through a synergistic mechanism of"structural loosening-functional group oxidation-hydrophilicity enhancement.This study provides a mo-lecular-level understanding and theoretical foundation for quantitatively describing coal-water reactivity,DOM release dynamics,and subsurface carbon migration processes in geothermal environments of deep coal seams.
Keywords：geothermal conditioncoal rankwater-coal interactionfunctional group evolutionhydrophilicity
Publication Date：2026-01-31
Pages：8( 20-27 )