Removal of metoprolol from water by sepiolite-supported nanoscale zero-valent iron

The presence of β-blockers (i.e. metoprolol (MPL)) as an emerging contaminant in aquatic environments has become a subject of concern because of their high solubility in water, consumption, and persistence. In this study, metoprolol was removed from water with sepiolite-supported nanoscale zero-valent iron (SPT-nZVI) to prevent agglomeration and provide a large reactive area. The SPT-nZVI was synthesized using the sodium borohydride reduction method and characterized by various techniques including Fourier-Transform infrared spectroscopy (FTIR), x-ray diffraction spectrometry (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDAX). The selected parameters of solution pH, contact time, H2O2 concentration, initial MPL concentration, and dosage of nanoparticles were investigated and optimized. The results indicated that the maximum MPL removal rates in the absence and presence of water anions and cations were 67.24% ± 0.95 and 55.16% ± 1.26, respectively, obtained under optimal conditions including an MPL concentration of 3 mg/L, 10 mM H2O2, SPT-nZVI dosage of 0.5 g/L, solution pH of 3, and contact time of 60 min. Kinetics study indicated that the removal of metoprolol was best fitted with the pseudo-second order model (R2 = 0.9907). Hydroxyl radical production was successfully verified through the scavenging effect of methanol.