Pb(II) Removal from Aqueous Solutions Using Green-Synthesized Iron Oxide Nanoparticles Derived from Centrifuge Used Tea and Their Antibacterial Properties Against E. coli and S. aureus

This study explores the synthesis of sustainable green iron oxide nanoparticles (gINPs) through environmentally friendly methods, utilizing biochemicals such as polyphenols and amino acids. Used Black tea extract was selected for synthesis procedure. Larger residuals were eliminated via centrifugation prior to mixing with iron precursor solution and calcination. The gINPs were characterized using a range of techniques, including the Field Emission Scanning Electron Microscopy (FeSEM), Dynamic light scattering (DLS), Energy Dispersive Xray Spectrometer (EDX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry, and zeta potential analysis. The nanoparticles demonstrated stability, with a zeta potential of -10.5 mV and a surface area of 16.1 m²/g. The efficiency of Pb(II) removal was influenced by various factors such as pH, contact time, mixing speed, initial concentration, gINPs dosage, and temperature. Over 90% removal was achieved within 20 min at room temperature and a pH above 5, with an adsorption capacity of 764 mg/g. The process followed a pseudo-first-order reaction and adhered to the Freundlich isotherm model. Furthermore, a 100 mg/mL concentration of gINPs resulted in inhibition zones of 12 mm against E. coli and 15 mm against S. aureus, highlighting their potential not only for efficient Pb(II) removal but also for possible applications in catalysis and antibacterial treatments.

Graphical Abstract