Premagnetization enhancing the reactivity of Fe0/(passivated Fe0) system for high concentration p-nitrophenol removal in aqueous solution

In order to strengthen the treatment efficiency of Fe0 based system for high concentration wastewater treatment, Fe0 particles were passivated by concentrated nitric acid, and a premagnetization Fe0/(passivated Fe0) system was setup for high concentration p-nitrophenol (PNP) removal in this study. The significant parameters of this system were optimized. Under the optimal conditions, the premagnetization Fe0/(passivated Fe0) system could obtain high kobs value for PNP removal (0.100 min−1) and COD removal (15.0% after 60 min) for high concentration PNP (500 mg/L) treatment. In addition, five control experiments were set up to confirm the advantage of the premagnetization Fe0/(passivated Fe0) system. The results suggest that passivated Fe0 particles could be stimulated better than Fe0 particles by premagnetization process, and the premagnetization Fe0/(passivated Fe0) systems is much superior to the other five control systems. Furthermore, the pathway for PNP destruction treated by 6 different systems was also proposed according to intermediates determination by High Performance Liquid Chromatography (HPLC) and UV-vis spectrum, and the carbon mass balance was demonstrated according to the COD and HPLC analyses. Finally, the characteristics of (premagnetization) Fe0 and passivated Fe0 was detected by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and vibrating sample magnetometer (VSM), and the mechanism of premagnetization effectively enhancing the reactivity of Fe0/(passivated Fe0) system (better than that of Fe0 system) was proposed. Consequently, the premagnetization for reactivity improvement of Fe0/(passivated Fe0) system is a promising technology to enhance the efficiency of this system for high concentration wastewater treatment.