Sustainable synthesis and functionalization of ZnO photocatalysts using Amphipterygium adstringens (Cuachalalate) bark extract for the effective degradation of emerging pollutants

Abstract

This study investigates the photocatalytic degradation of emerging pollutants (EP) using zinc oxide nanoparticles (ZnO NPs) synthesized via green chemistry. It employs Amphipterygium adstringens (Cuachalalate) bark extract as a natural reducing and stabilizing agent. The photocatalytic performance of the synthesized ZnO NPs was evaluated under ultraviolet (UV) light irradiation using various model compounds, including the dyes Congo Red (CR), Malachite Green (MG), Rhodamine B (RhB), Methylene Blue (MB), and Methyl Orange (MO), as well as the pharmaceutical contaminants Ibuprofen (IBU), Ciprofloxacin (CIP), and Diclofenac sodium (DCF). Characterization techniques determine the physical, chemical, and electronic properties of ZnO NPs. Ultraviolet–visible (UV–Vis) spectroscopy presents an absorbance peak at 371 nm, and the TAUC plots of each spectrum revealed band gaps of 2.948, 2.940, and 2.847 eV for 1%-ZnO NPs, 2%-ZnO NPs, and 4%-ZnO NPs, respectively. At the same time, the obtention vibration bonds through FTIR spectroscopy showed Zn–O stretching vibration at 380 cm⁻¹. X-ray diffraction (XRD) shows the crystalline structure, with average crystallite sizes of 21.6 nm, 14.19 nm, and 13.26 nm for 1%-ZnO NPs, 2%-ZnO NPs, and 4%-ZnO NPs, respectively. Finally, scanning electronic microscopy showed the morphology, which was spherical with a slight agglomeration of the particles. The photocatalytic degradation efficiency of the ZnO NPs was approximately 90% for dyes and 85% for drug contaminants. The degradation constant was determined using the equation of first-order kinetics. These promising results highlight the potential of Cuachalalate-derived ZnO NPs for efficiently remedying emerging pollutants and suggest further environmental application research, pollutants and suggest for further research in environmental applications.