This research explores the synthesis of zinc oxide nanomaterials (ZnO NMs) through the utilization of neem leaf extract, presenting an environmentally conscious and sustainable methodology. The biosynthesized ZnO NMs exhibit dual functionality, showing remarkable efficacy in the photocatalytic degradation of natural organic matter (NOM) as well as antimicrobial activity against drug-resistant microorganisms. Under low-energy UV light, ZnO effectively degraded 92 % of NOM within a span of 180 min, concurrently exhibiting substantial antimicrobial effects against Escherichia coli and Candida albicans , characterized by significant inhibition zones. The research further highlights the application of low-energy UV light to improve the photocatalytic efficiency of ZnO NMs, thereby promoting sustainability and reducing the toxicity of by-products. The characterization of ZnO NMs was conducted employing various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–vis), and scanning electron microscopy (SEM). At a concentration of 3 g/l, ZnO accomplished a 92 % reduction in NOM over a period of 180 min, accompanied by a 59 % reduction in organic carbon deposition (OCD). The low levels presence of OCD on the surface after the reaction further confirmed the effectiveness of the process. The findings highlight the promise of neem-extract ZnO NMs as an eco-friendly and adaptable substance for environmental cleanup and antimicrobial uses, demonstrating significant antibacterial efficacy at concentrations of 0.05 mg/ml and 0.1 mg/ml.

Textile dyes are one of the dominant reasons for water pollution. Among these dyes, Orange G is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to humans and marine life. Therefore, in this present work, a novel photocatalyst was synthesized, and systematic degradation of Orange G dye was investigated. The novel ZnO/ZIF-8 nanocomposite has been successfully synthesized via a two-step method, thermal decomposition for ZnO and wet-chemical method for ZnO/ZIF-8 nanocomposite. The band gap of the nanocomposite was calculated using a KM plot and found to be 3.5 eV. The surface charge of the materials was examined using zeta potential measurement, which was found to be suitable for dye degradation. The recombination time of the materials was investigated using Time-Resolved Photoluminescence (TRPL) study, and it was found that nanocomposite has a lower recombination rate than pristine materials. The degradation efficiency of materials towards Orange G dye was calculated to be ∼95% after 120 min illumination. The photocatalysis mechanism was proposed on the basis of Mott–Schottky measurements, which were supported by the scavenger test. Furthermore, to evaluate the reusability of the nanocomposite, a photocatalytic experiment was conducted several times. The ZnO/ZIF-8 nanocomposite could be used for the degradation of textile dye wastewater.