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

Wan, Dong, Li, Wenbing, Wang, Guanghua, Lu, Lulu, Wei, Xiaobi
The Science of the total environment 2017 v.574 pp. 1326-1334
analysis of variance, catalysts, chemical oxygen demand, gas chromatography-mass spectrometry, hydrogen, hydrogen peroxide, hydroxyl radicals, leaching, magnetite, models, oxidation, p-nitrophenol, pH, prediction, response surface methodology, temperature
A Coke supported Fe3O4 and Fe0 composite (Fe0/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 Fe0/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, R2=0.9952) was derived using analysis of variance (ANOVA). Optimum conditions were determined to be 1.3g/L catalyst, 32°C, pH3.1 and 11.3mM H2O2. 100% of p-NP (100mg/L) conversion and 81% of COD removal were achieved after 120min of reaction time, respectively, under the optimum conditions, which agreed well with the modeling prediction. The recyclability of Fe0/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 (•OH) mechanism.