DYNAMIC INSITU 9 GHZ CW-EPR LOW-TEMPERATURE OXIDATION STUDY OF SELECTED ALBERTA COALS .4. INFLUENCE OF MOISTURE ON HV BITUMINOUS COAL

The results are reported of a dynamic in situ 9 GHz c.w.-e.p.r. study in the temperature interval 20 to 250-degrees-C of virgin, dried and moisture-saturated hv bituminous coal samples subjected to dry air flow. The c.w.-e.p.r. spectral parameters and the relative total spin concentration were found to be sensitive indicators of the role of moisture in determining the free radical content of a coal sample. The relative total spin concentration in the dried sample was twice that of the other two samples at 20-degrees-C and was essentially temperature-independent, whereas it increased very rapidly between 20 and 100-degrees-C and attained a maximum near 100-degrees-C in both the virgin and moisture-saturated samples. The lineshape changes were most pronounced in the moisture saturated sample and occurred between 20 and 100-C. This lineshape may be the composite of lineshapes due to three resonances, but only one of the free radical resonances is moisture-sensitive.