Degradation of p-nitrophenol (PNP) in aqueous solution by a micro-size Fe0/O3 process (mFe0/O3): Optimization, kinetic, performance and mechanism

A micro-size Fe-0/O-3 process (mFe(0)/O-3) was setup to degrade p-nitrophenol (PNP) in aqueous solution, and its key operational parameters (i.e., initial pH, ozone flow rate, and Fe-0 dosage) were optimized by the semibatch experiments, respectively. Under the optimal conditions, COD removal efficiency (89.5%) obtained by the mFe(0)/O-3 process was about two times of the sum (44.8%) of COD removal obtained by Fe-0 alone and O-3 alone. The results suggest that the synergetic effect between O-3 and Fe-0 in the mFe(0)/O-3 process played a vital role in the degradation of PNP. In addition, treatment efficiency of the mFe(0)/O-3 process also was much higher than some of the present technologies (e.g., Fe-0/air process, MnO2/O-3 and Al2O3/O-3), which confirm the superiority of the mFe(0)/O-3 process. Furthermore, the degradation mechanism and pathway of PNP was proposed according to the analysis results of UV vis, FTIR, IC and GC MS. According to the present literature and analysis data of SEM, EDS and XRD analysis, it can be concluded that the high-efficient mFe(0)/O-3 process was mainly resulted from the combination of homogeneous or heterogeneous catalytic ozonation, Fenton-like reaction, adsorption and precipitate. Therefore, the mFe(0)/O-3 process was a promising technology for the refractory industrial wastewater. (C) 2016 Elsevier B.V. All rights reserved.