Comparative Study of Green Synthesis to Prepare TiO₂ Nanoparticles from Plant Shard Leaves Extract by Using Microwave Irradiation and Microjet Plasma

Plant extracts have been widely investigated as a safer alternative for the green synthesis of metal oxide nanoparticles. This study presents a green synthesis approach using shard leaf extract assisted by microwave irradiation and microjet plasma for the preparation of titanium dioxide nanoparticles (TiO2 NPs). The synthesized nanoparticles were characterized using Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), and zeta potential (ZP) analysis. XRD results confirmed the formation of the anatase phase of TiO2 without detectable brookite or rutile peaks, indicating high phase purity. The crystal structure was tetragonal with average crystallite sizes of 11.05 nm and 11.04 nm for microwave and microjet plasma methods, respectively. UV–Vis analysis revealed band gap energies of 3.55 eV and 3.43 eV for the respective synthesis methods. FESEM images showed irregular spherical nanoparticles with average diameters ranging from 43.48 to 46.52 nm. Zeta potential measurements indicated moderate stability of the nanoparticles with values of 76.8 mV and -68.5 mV. The antibacterial activity of TiO2 NPs was evaluated against Gram-positive and Gram-negative bacteria, showing higher effectiveness against Gram-positive bacteria such as Staphylococcus aureus compared to Escherichia coli. Additionally, the nanoparticles demonstrated excellent adsorption efficiency for heavy metals, including lead, chromium, and cadmium, achieving up to 100% removal from aqueous solutions. These results highlight the potential of green-synthesized TiO2 nanoparticles for environmental remediation and antibacterial applications.