Green synthesis of TiO2 nanoparticles using Echinops echinatus plant extract and its potential applications for photocatalytic dye degradation, 4-nitrophenol reduction, and antimicrobial activity

Industrial wastewater poses a significant threat to human health and the environment. Numerous treatment methods have been developed to mitigate harmful compounds. The production of multifunctional titanium oxide nanoparticles (TiO2-NPs) for wastewater treatment through green synthesis is a desirable alternative to conventional methods. This study reports using Echinops echinatus leaves (EES) as an effective bio-reductant for the green synthesis of TiO2-NPs. A simple and eco-friendly process with low reaction time and temperature was adopted for the EES-mediated synthesis of TiO2-NPs. Various spectroscopic and microscopic techniques were used to characterize the synthesized nanoparticles. The UV-visible spectrophotometer spectra showed an absorbance peak at 289 nm and a bandgap of 2.91 eV. SEM and XRD revealed the nanoparticles' crystal nature, size, and spherical morphology. HR-TEM indicated an average particle size of 36 nm with a spherical shape. Energy-dispersive X-ray (EDX) spectra confirmed the presence of titanium. Fourier transform infrared (FTIR) spectroscopy identified the fundamental biomolecules responsible for reducing and stabilizing the TiO2 nanoparticles. The synthesized nanoparticles were developed as photocatalysts for treating trypan blue dye under visible light irradiation, achieving a rapid decomposition rate with 84% degradation efficiency and catalyst reusability. The radical experiment that was studied identified h(+) and OH* radicals as the more reactive species. The catalytic potential of EES-TiO2 NPs was further examined for converting 4-nitrophenol to 4-aminophenol, with a 98% conversion rate in an alkaline medium. UV-vis spectroscopy showed a decrease rate of k = 0.011 min(-1) during the catalytic conversion. Additionally, EES-TiO2 NPs demonstrated significant antibacterial effects on pathogenic bacteria, as measured by the zone of inhibition in the disc diffusion method. The findings suggest that the synthesized EES-TiO2 nanoparticles hold promise for various environmental and antipathogenic applications.