Monitoring the advanced oxidation of paracetamol using ZnO films via capillary electrophoresis

With the goal of investigating the effect on ZnO on the photo-chemical degradation of pharmaceuticals (using paracetamol as a model compound), a thin film of ZnO was grown -by means of ultrasonic spray pyrolysis on glass substrates. The morphology, crystalline structure and elemental composition of the obtained thin films were determined by scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy techniques. UV–vis spectroscopy was used to determine the corresponding optical bandgap. To evaluate the catalytic activity of zinc oxide films towards the degradation of selected pharmaceutical compounds, capillary electrophoresis was used. The structure of the byproducts generated during the photocatalytic reactions, was determined by gas chromatography coupled with mass spectroscopy. According to our results, the film allowed coupling relatively mild conditions (0.35 % H₂O₂ and UV light 365 nm / 6 W cm⁻²) and still reach a degradation efficiency of 88.1 %. Under the selected experimental conditions, the approach was also applicable to other compounds with similar properties (diclofenac, paracetamol, diflunisal and acetylsalicylic acid).