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

Ren, Yi, Li, Jun, Lai, Leiduo, Lai, Bo
Chemosphere 2018 v.194 pp. 634-643
X-radiation, aqueous solutions, carbon, chemical oxygen demand, energy-dispersive X-ray analysis, high performance liquid chromatography, iron, nitric acid, p-nitrophenol, scanning electron microscopy, ultraviolet-visible spectroscopy, wastewater treatment
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.