DYNAMIC INSITU 9 GHZ CW-EPR LOW-TEMPERATURE OXIDATION STUDY OF SELECTED ALBERTA COALS .2. INFLUENCE OF MINERAL MATTER IN AN HV BITUMINOUS COAL

The effect of the presence of manganese and cobalt impurity ions on the formation of free radicals in the low-temperature oxidation of an Alberta hv bituminous coal has been investigated using dynamic in situ 9 GHz c.w.-e.p.r. spectroscopy. Changes in the effective g-factor and effective linewidth DELTAB1/2 e.p.r. spectral parameters as well as in the relative total spin concentration and the lineshape were monitored in both virgin and demineralized coal samples subjected to dry air flow whilst being heated from 20 to 250-degrees-C. The virgin sample produced a larger number of free radicals than the demineralized sample when heated. This demonstrates that the presence of transition metal ions in the mineral matter component of the virgin coal plays an important role in promoting the low-temperature oxidation process. It is shown that two free radical species are present and that the presence of the transition metal ions promotes the preferential creation of the free radical with the larger g-factor.