Synthesis, characterization, and effective removal of dye pollutants from water bodies using a new ZnO nanocomposite

Biogenic zinc oxide nanocomposites were fabricated through an eco-friendly method by employing Boerhaavia diffusa leaf extract in combination with zinc nitrate. The nanocomposites underwent a comprehensive characterization process involving uv-visible spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), selected area diffraction (SAED), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDAX), high-resolution transmission electron microscopy (HRTEM), inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), and zeta potential studies. The XRD analysis substantiated the existence of a ZnO nanocomposite possessing a hexagonal wurtzite crystalline structure. Furthermore, extended rod-shaped formations were identified in conjunction with clusters of sodium and potassium. The effectiveness of the ZnO nanocomposite in photocatalytic degradation was assessed for various types of dyes: cationic and anionic like Methylene Blue (MB), Malachite Green (MG), Congo Red (CR), and Methyl Orange (MO) in aqueous medium. The nanocomposites demonstrated remarkable photodegradation capabilities for both cationic and anionic dyes. Notably, 50 mg of the catalyst effectively removed Congo Red (15 ppm) and Methylene Blue (15 ppm) within 40-60 min under direct sunlight and 15-30 min under UV illumination. The samples are more active on UV light illumination rather than exposure to sunlight due to. the favorable semiconductor band gap (3.26 eV). As a result, this research suggests an uncomplicated, budgetfriendly, and environmentally sustainable approach for manufacturing a ZnO-based photocatalyst. Moreover, the inclusion of potassium and sodium elements in the nanocomposite showcased a beneficial synergistic impact on its photoactivity. This necessitates additional scrutiny for its potential application in treating diverse organic pollutants in water resources. Additionally, high efficiency of the catalyst under direct sunlight holds potential for applications in solar cells.