Synthesis of magnetic Fe3O4 nanoparticles from scrap iron and use of their peroxidase like activity for phenol detection

Abstract The present study was initiated to check the feasibility of using leach liquor as a precursor for the synthesis of magnetite (Fe 3 O 4 ) nanoparticles (MNPs). The leaching of iron was carried out from scrap iron using citric acid. The results show that 40 mL citric acid solution (0.5 M) was sufficient to solubilize 2 cm 2 work-piece in 7 days at 30 °C and 150 rpm. The increase in number of work-pieces decreased the leaching efficiency. The leach liquor obtained from this process was used for the synthesis of nanoparticles. Sodium borohydride (NaBH 4 ) was used as a reducing agent for co-precipitation of nanoparticles. X-ray diffraction (XRD) analysis showed the presence of Fe 3 O 4 . Transmission electron microscope (TEM) observations indicated that MNPs were elliptical or sphere shaped with an average size of 7 nm. The as synthesized MNPs were superparamagnetic in nature with 0.83506 G coercivity (Hc) and 11.51 emu/g saturation magnetization (Ms). Further, the MNPs showed peroxidase like activity. This ability of MNPs was used for the detection of phenol in the concentration range between 1 μM–200 mM.