Photocatalytic degradation is a popular method for oxidation of organic pollutants. While many studies have demonstrated the effectiveness of this method, fewer reports on the mechanisms exist, and nearly all are limited in temporal resolution because of the use of chromatographic and colorimetric methods. For many systems, however, mechanistic information at higher rates can be collected using Raman spectroscopy. Because Raman spectroscopy is insensitive to water vibrations and robust even for turbid and heterogeneous media, it is an ideal approach for the study of semiconductor photocatalysis. To demonstrate the feasibility of this technique, we present time-resolved Raman spectra monitoring the photocatalytic degradation of aqueous solutions of the x-ray contrast media diatrizoate and iohexol. Internal standards allow for quantitative studies. The spectra are interpreted with the aid of quantum mechanical structural calculations, showing areas most susceptible to the initial oxidative attack.

Monitoring photocatalytic degradation mechanisms non-invasively with Raman spectroscopy

244th National Meeting (2012)

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