Monitoring Photocatalytic Degradation of X-ray Contrast Media with Raman Spectroscopy

X-ray contrast media such as diatrizoate and iohexol have been found in wastewater and drinking water and are difficult to remove because they are resistant to water treatment processes. A removal process can be started with ultraviolet photocatalytic degradation of X-ray contrast media in the presence of titanium dioxide or other catalysts. Raman spectra of diatrizoate and iohexol were taken in an aqueous solution in the presence and absence of titanium dioxide during exposure to ultraviolet radiation. Raman intensity is directly proportional to concentration; therefore, we can measure the rate of the reaction based on changes in the Raman spectrum. Changes were monitored for eight hours. Evidence of photoreaction is observed, indicating that the degradation of X-ray contrast media can be measured using Raman spectra. To our knowledge, this represents the first use of Raman spectroscopy to monitor photocatalytic degradation in real time, opening a potentially powerful approach to studying the removal of pollutants in the environment