Efficient removal of nitrobenzene by Fenton-like process with Co-Fe layered double hydroxide

Co-Fe layered double hydroxide (Co-Fe LDH) prepared by the co-precipitation method was proposed as the Fenton-like catalyst for nitrobenzene removal. The properties of prepared catalysts were characterized by BET, SEM and XRD analyses. The initial pH, hydrogen peroxide concentration, catalyst dosage and the nitrobenzene concentration on the removal of nitrobenzene have been studied. The best removal efficiency (100%) was obtained at pH = 2.7, [H2O2]0 = 500 mg/L, catalyst dosage = 1 g/L for the initial concentration of 50 mg/L nitrobenzene. Co-Fe LDH retained the catalytic activity after five cycles. The mechanism of nitrobenzene oxidation was radical mediated process, confirmed by the addition of T-butanol (·OH scavenger). The iron leaching was only 12.47 mg/L even at pH 2.7. Moreover, the intermediates were detected by LC/MS and a possible pathway for nitrobenzene removal in the Co-Fe LDH and H2O2 system was proposed.