Efficient removal of the recalcitrant metamizole contaminant from drinking water by using a CaLaCoO perovskite supported on recycled polyethylene.

Metamizole (MZ) is a widely used anti-inflammatory drug. Due to its common use, this contaminant is found in sewage and rivers. In order to reduce the contamination produced by the MZ, we fabricated in this work a photocatalytic composite using recycled polyethylene (RPE) and the CaLaCoO (LCCO) perovskite. Those nanoparticles had a microplate-like morphology and sizes of 1.4-5.5 µm according to the analysis of microscopy. The photocatalytic properties of the LCCO powders were evaluated under ultraviolet-visible (UV-Vis) irradiation and found a removal efficiency of 96%. When the RPE+LCCO composite was employed for the photocatalytic degradation of MZ, a maximum degradation of 92.5% was obtained. The influence of the pH on the photocatalytic activity was also studied and found that an initial pH = 3 produced a total degradation of MZ after 240 min of UV-Vis irradiation. Moreover, three reuse cycles were carried out for the pure LCCO powders and for the RPE+LCCO composites and found that the maximum loss of degradation was 5%. Furthermore, scavenger experiments demonstrated that the super oxide and hydroxyl radicals are formed during the photocatalytic reaction and were responsible for the degradation of MZ. Additionally, the X-ray photoelectron-spectroscopy and Raman analysis demonstrated the formation of defects (oxygen vacancies), those ones delayed the electron-hole recombination, which in turn, enhanced the degradation of the MZ. Thus, the studies performed in this work proved that composites made with recycled plastics and LCCO perovskites are a low-cost and feasible alternative for the cleaning of water sources polluted with pharmaceutical compounds.