Infrared spectroscopy confirms that clean separations are obtained. This technique involves passing an infrared beam through a thin film of material or scattering the light from its surface. The amount of light absorbed as a function of the frequency of the light (measured in wavenumbers, cm–1) is then plotted.
Different chemical groups absorb at different frequencies, providing a kind of “molecular fingerprint” of a material. The infrared spectrum of a parent oil sand is shown as the green plot in the figure below. It has bands (labeled) due to hydrocarbons (bitumen), which show up as fairly weak absorptions near 2800 cm–1. The recovered bitumen (red plot at the top) has very strong bands in this region of the spectrum, as one would expect.
On the other hand, the extracted minerals have almost undetectable bands in this region. Similarly, the very strong mineral bands below 2000 cm–1 are absent in the spectrum of the recovered oil.
