Chitosan–Schiff Base Cu(II) Complex-Grafted ZnO Nanoparticles as a Photocatalyst for Degrading Pharmaceutical Pollutants Under Diverse Light Sources
摘要
In this study, Zinc oxide nanoparticles were prepared hydrothermally and incorporated into the Chitosan–Schiff base Cu(II) complex to form a ZnO-Chitosan–Schiff base Cu(II) (ZnO-CSBCu) nanocomposite. The photocatalytic activity of the synthesized nanocomposite was investigated for the degradation of pharmaceutical pollutants, including tetracycline (TC), paracetamol (ANPA), and aspirin (ASA) under various light sources UV (254 and 365 nm), visible light, and sunlight and at different pH values (3.0, 7.0, and 10.0). It was observed that the degradation of three pollutants was more efficient under sunlight, in an acidic environment (pH 3.0). This enhancement is achieved through improved charge separation and increased active site availability provided by the Cu(II) complex and Chitosan matrix. Structural, morphological, and optical properties of the nanocomposite were characterized by XRD, UV–Vis, FTIR, SEM–EDX, and PL techniques. XRD confirmed the crystalline structure of ZnO, with an average particle size of 18.56 nm, while FTIR spectra revealed Zn–O bond stretching frequencies at 613 cm−1 and 671 cm−1. SEM images demonstrated a nearly spherical morphology and a homogenous distribution of nanoparticles. UV–Vis spectroscopy confirmed the absorption characteristics of ZnO, with a calculated band gap of 3.25 eV using Tauc’s relation. Photoluminescence (PL) analysis indicated that the ZnO-CSBCu nanocomposite significantly reduced charge carrier recombination rates. These findings highlight the potential of the ZnO-CSBCu nanocomposite as an efficient and sustainable photocatalyst for the removal of pharmaceutical pollutants from water, and they provide the basis for further development and application in environmental remediation.