Graduate Student Domenica Fertal

"Photodegradation of Acid Violet 3 and Fallacies in Chemical Oxygen Demand"

The facile synthesis of azo dyes has led to their widespread use in the textile industry. The textile dyeing process releases up to 280,000 tons of azo dyes into natural waterways annually, polluting local water sources and causing harm to the local ecosystem. Previously explored techniques to degrade azo dyes focus on the water treatment apparatus, with less emphasis on the mechanism of azo dye degradation. In this work, I explore how the intrinsic photophysical properties of azo dyes allow them to be the initiator for their own photodegradation by illuminating an acidic azo dye in the presence of a sacrificial oxidant. My results show that degradation via illumination of the dye occurs most efficiently with wavelengths of light less than 400 nm. Based on my results, I hypothesize that oxygen presence is necessary to achieve degradation because it is used to generate reactive oxygen species (ROS). My work suggests that two different ROS pathways contribute to the degradation of the dye. I utilized chemical oxygen demand (COD) measurements to evaluate the extent of azo dye degradation in this system and uncovered significant discrepancies in the results attributed to premature oxidation of the dyes. These data provide insights into a mechanism of self-initiated dye degradation. My work in the near-future will utilize the mechanism identified in this model system by translating it to a metal-organic framework that can act as a heterogeneous catalyst for azo dye degradation.