Synthesis and characterization of magnetic nanoparticles: Biocatalytic effects on wastewater treatment

Abstract

Wastewater treatment plants have experienced some setbacks over the years which makes it inefficient. This has intensified the use of nanotechnology in environmental remediation purposes with researchers delving into the modification of nanoparticles with recoverability benefits. In this study, magnetic nanocomposites (Fe3O4 and NiFe2O4) were prepared by a modified co-precipitation method for the bio-decontamination of wastewater. The physicochemical properties of the prepared nanocomposites were characterized by using scanning electron microscopy/energy dispersive X-ray (SEM/EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The surface morphology and elemental compositions of the nanocomposites were defined by the high micrograph of the SEM/EDX, whereas the crystal structure (face-centred cubic shape) and size (5.179 nm) were affirmed by the XRD. The hydroxyl, amino and carboxyl groups of the nanocomposite intermediates and the possible decomposition route were revealed by the FTIR. Biochemical methane potential (BMP) assay was employed to reveal the treatability performance (COD, colour and turbidity removal), biogas yield and composition. At anaerobic condition of 40 °C and 21 days, the degradation efficiency of 60–90% was achieved by the bioreactors doped with nanocomposites (Fe3O4 and NiFe2O4) as compared with 50–65% efficiency by the control system. In general, the bioreactor was significantly inhibited by the Fe3O4 which increased the biogas and methane yield of 280 mL/day and 100% CH4 respectively as compared to the control of 55 mL/day and 66% CH4.