Green Synthesis of ZnO Nanoparticles Using Licania tomentosa Benth (Oiti) Leaf Extract: Characterization and Applications for the Photocatalytic Degradation of Crystal Violet Dye

Efficient plant biomass utilization is a key component in advancing a sustainable and circular bioeconomy. ZnO nanoparticle synthesis using plant extracts is actively studied as a part of this effort. Here, green ZnO nanoparticles were prepared using Licania tomentosa Benth (also known as Oiti) leaf extract. Characterization of the produced green ZnO nanoparticles (NPs) involved X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy (UV-Vis) techniques. Furthermore, we investigated photocatalytic degradation of the crystal violet (CV) dye catalyzed by the obtained ZnO NPs and evaluated the efficiency of the photodegradation process. The synthesized nanoparticles have an average crystallite size of 12.4 nm, as measured by XRD and have a spherical shape as revealed by SEM. UV–Vis studies show that ZnO nanoparticles have a relatively small band gap of 2.75 eV, as estimated by Tauc plot. The photodegradation activity tests using synthesized green ZnO NPs showed that approximately 79% of CV dye is decomposed in 2 h after being exposed to UV irradiation under experimentally studied conditions. The photodecomposition of CV is impacted by different factors, such as the catalyst bandgap and loading, the pH and the intensity of light. Moreover, an optimum photocatalyst loading was determined. Our studies reveal that Oiti leaf extract can be efficiently used for ZnO NPs synthesis, which has significant potential for photodegradation applications.