Degradation of p-Nitrophenol using magnetic Fe0/Fe3O4/Coke composite as a heterogeneous Fenton-like catalyst

A Coke supported Fe3O4 and Fe-0 composite (Fe-0/Fe3O4/Coke) was prepared for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the Fenton degradation of p-Nitrophenol (p-NP). A four factor Box-Behnken design (BBD) coupled with response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely Fe-0/Fe3O4/Coke dosage, reaction temperature, initial pH and H2O2 concentration, on the removal efficiency of p-NP. A significant quadratic model (p-value < 0.0001, R-2 = 0.9952) was derived using analysis of variance (ANOVA). Optimum conditions were determined to be 13 g/L catalyst, 32 degrees C, pH 3.1 and 113 mM H2O2. 100% of p-NP (100 mg/L) conversion and 81% of COD removal were achieved after 120 min of reaction time, respectively, under the optimum conditions, which agreed well with the modeling prediction. The recyclability of Fe-0/Fe3O4/Coke was also investigated after three successive runs, in which p-NP degradation, performances showed a slight difference with the first oxidation cycle with an acceptable iron leaching. Moreover, according to the main intermediate products identified by gas chromatography-mass spectrometry (GC-MS), a possible pathway of p-NP degradation was proposed based on hydrogen radicals ([H]) or hydroxyl radicals (center dot OH) mechanism. (C) 2016 Elsevier B.V. All rights reserved.