Thin film water non-thermal plasma reactor for acetaminophen analgesic oxidation

Occurrence of acetaminophen in wastewater and surface waters is a worldwide concern. This study analyzes the application of a dielectric barrier discharge reactor for non-thermal plasma generated in Ar–O₂ mixtures on a thin film of acetaminophen aqueous solution in order for this pharmaceutical compound to be oxidized. Solution samples collected during the process were analyzed with gas chromatography mass spectrometry technique. At the end of the process, the treated solution was filtered with a Solid Phase Extraction cartridge, and the by-products were recovered with methanol ACS and analyzed immediately. It can be seen from the results obtained that, firstly, the degradation efficiency largely dependents on the operating parameters; secondly, degradation efficiencies of up to 97% were obtained when O₂ reached 20% in the gas phase; and finally, hydroquinone, acetamide and other aromatic products were identified as degradation by-products. The nature of the by-products detected indicates that the acetaminophen oxidation pathway occurred through ^•OH radical reaction instead of the direct O₃ reaction.