This study aims to investigate the degradation mechanism of lemon yellow (a common azo dye) using dielectric barrier discharge (DBD) plasma, focusing on the influence of key operational factors (current, voltage, time and initial concentration) on decolorization and degradation efficiency. Additionally, this research sought to identify and characterize the major degradation products to elucidate the underlying degradation pathway.
DBD plasma is applied under varying conditions (current, voltage, time and initial concentration) to assess their effects on lemon yellow degradation. Degradation products are isolated via thin-layer chromatography. The degradation products are structurally characterized using infrared spectroscopy, mass spectrometry and nuclear magnetic resonance. The degradation mechanism of DBD plasma treatment of lemon yellow was analyzed based on the structural characteristics of the degradation products.
Four factors – current, voltage, time and initial concentration – were investigated, and all were found to significantly affect both the decolorization and degradation efficiency of lemon yellow. During the degradation process, three characteristic degradation products were successfully isolated and identified: benzenesulfonic acid, p-hydroxybenzenesulfonic acid and 4-amino-5-oxo-2-pyrazoline-3-carboxylic acid. The degradation pathway likely involves the cleavage of azo bonds and subsequent oxidation.
This study provides mechanistic insights into the DBD plasma-induced degradation of lemon yellow, contributing to the understanding of advanced oxidation processes for azo dye removal.
