Synthesis, magnetic properties, biotoxicity and potential mechanism of modified nano zero-valent iron for decolorization of dye wastewater.

SiO-coated nano zero-valent iron (nZVI) has emerged as a fine material for the treatment of dye wastewater due to its large specific surface area, high surface activity, and strong reducibility. However, the magnetic properties based on which SiO-coated nZVI (SiO-nZVI) could effectively separate and recover from treated wastewater, and the biotoxicity analysis of degradation products of the dye wastewater treated by SiO-nZVI remain unclear. In this study, SiO-nZVI was synthesized using a modified one-step synthesis method. The SiO-nZVI nanoparticles were characterized using Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Fully automatic specific surface and porosity analyzer, Vibrating sample magnetometer, and Zeta potential analyzer. The removal rate of methyl orange (MO) by SiO-nZVI composite reached 98.35% when the degradation performance of SiO-nZVI treating MO was optimized. Since SiO-nZVI analysed by magnetic hysteresis loops had large saturation magnetization and strong magnetic properties, SiO-nZVI exhibited excellent ferromagnetic behaviour. The analysis of the degradation products showed that the MO treated by SiO-nZVI was converted into a series of intermediates, resulting in reducing the toxicity of MO. The potential mechanism of MO degradated by SiO-nZVI was speculated through degradation process and degradation kinetics analysis. Overall, the SiO-nZVI composite may be regarded as a promising catalyst for decolorization of dye wastewater.