A novel magnetically separable pH sensitive surface-active iron oxide nanoparticles for the removal of antibiotics (tetracycline) from aquatic environments

This research examines the application of magnetic iron-oxide (Fe₃O₄) nanoparticles (IONPs) for the targeted removal and recovery of tetracycline (TC) from aqueous systems. The IONPs were synthesized through a steady-state headspace with NH_3(g) at room temperature and pressure without mechanical agitation. IONPs were found to be in a single phase with uniform size distribution and magnetic separability. Effects of pH on surface charge, dispersity, and particle size were studied using zeta potential and DLS. Sorption profiles at various mass loadings for antibiotics (1–25 ppm) and nanoparticles (0.1–0.5 mg/mL) were studied using UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) imaging and energy dispersive X-ray (EDX) analysis. Results suggested a rapid sorption of TC onto IONPs with overall TC removal efficiency from wastewater ranging between 70% and 95% depending on temperature (10, 25, and 45°C) and contact time (1–90 min). The investigation into adsorption mechanisms demonstrated that adsorption of TC onto IONPs was feasible, spontaneous, and an endothermic process primarily governed by physisorption. The process well aligned with Freundlich isotherm and pseudo-second order kinetics. Further, stability of IONPs and desorption ability were also evaluated. The results suggest that IONPs can be used as a sustainable alternative to commercial adsorbent for removal of antibiotics from waterbodies.