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 Fe-0 based system for high concentration wastewater treatment, Fe-0 particles were passivated by concentrated nitric acid, and a premagnetization Fe-0/(passivated Fe-0) 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 Fe-0/(passivated Fe-0) system could obtain high k(obs) 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 Fe-0/(passivated Fe-0) system. The results suggest that passivated Fe-0 particles could be stimulated better than Fe-0 particles by pre-magnetization process, and the premagnetization Fe-0/(passivated Fe-0) 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) Fe-0 and passivated Fe-0 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 Fe-0/(passivated Fe-0) system (better than that of Fe-0 system) was proposed. Consequently, the premagnetization for reactivity improvement of Fe-0/(passivated Fe-0) system is a promising technology to enhance the efficiency of this system for high concentration wastewater treatment. (C) 2017 Elsevier Ltd. All rights reserved.