FTIR analaysis of coal. 1. techniques and determination of hydroxyl concentrations

The preparation of coal samples for the determination of hydroxyl content by FTIR is described. It is concluded that the FTIR method provides good quality infrared spectra on opaque materials such as coal and char. If sample preparation procedures are followed carefully, quantitative spectra of coals can be reproduced within ±5%. Beer's law is followed in the range 0.3–1.3 mg of coal/cm². The broad absorbance in the range 2000–3600 cm^?1 appears when using several different preparation techniques and is caused by hydrogen-bonded OH. The use of quantitative FTIR specta offers a simple method of estimating the hydroxyl content of a coal. Reasonable results have been obtained despite the problem of interference by water. The KBr pellets were dried for 48 h at 105 °C and the absorbance was reduced at 3200 cm^?1 and the problem of scattering was minimized by using a rectilinear baseline. With these procedures the hydroxyl oxygen concentrations in the coal were determined to an accuracy of ±10%.