Recent studies show increasing amounts of harmful organic pollutants in wastewater. Fortunately, many organic pollutants can be broken down into harmless end products via photolysis. However, more information on the kinetics and intermediates of these reactions is needed to determine their safety. Ideally, surface enhanced Raman spectroscopy (SERS) can be used to monitor reactions in real time, up to 100 times faster than gas chromatography-mass spectrometry, and with high sensitivity. SERS involves the use of semi-aggregated gold nanoparticles (NPs) to greatly enhance the Raman intensity of adsorbed analytes. However, over-aggregation of the NPs leads to sedimentation which reduces Raman intensity over time. A capping agent can be used to arrest aggregation and improve NP stability. Using the capped NPs, photolysis can be monitored by analyzing the changes in the analyte’s Raman spectra over the course of the reaction. The capped NPs were found to be stable in a wide range of pH (3 to 11). In this experiment a common dye and a common pesticide were used as the analytes. In the absence of UV-radiation, the Raman intensity of analytes showed little to no decrease over time, indicating the NPs were stable and did not sediment. In the presence of UV-radiation, spectral changes were seen in the Raman spectra of the analytes, indicating molecular changes in the analytes. The results of this experiment show the potential of capped NPs as a tool to monitor the photodegradation of organic molecules.

Using surface enhanced Raman spectroscopy to monitoring photo-induced degradation of organic pollutants

2019 Spring National Meeting

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