Solar-Assisted Photodegradation of Paracetamol Using ZnO-Coated Brass Plates in a Rotating Photoreactor

Abstract Rotating structured photoreactor with brass sheets covered with ZnO for the degradation of paracetamol (PAR) was used. The brass plates were calcined and coated with a zinc oxide suspension. The BZnO photocatalysts were characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The photodegradation experiments of the PAR were performed under UVA/UVB radiation for 6 h based on a 2² factorial experimental design with the central point in triplicate, in which the influence of pH (5, 7, and 9) and the mass ratio of the catalyst per substrate area (1; 1.5 and 2 mg.cm-²) was studied. The best result was obtained at pH 5 and a ratio of 2 mg.cm-2 with a degradation of 95.0%. The influence of the type of radiation (solar, visible, and UVC) was studied, obtaining a degradation of the drug of approximately 78% with solar radiation. The photocatalyst reuse experiments showed good stability of the ZnO on the brass plates, presenting an efficiency of 88.3% after five reaction cycles. The kinetic study was conducted using the pseudo-first-order model in two stages. Toxicity tests using seeds indicated the absence of toxic compounds after photodegradation.