Degradation of acetic acid by heterogeneous Fenton-like oxidation over iron-containing ZSM-5 zeolites

• Iron-containing ZSM-5 zeolite catalysts were prepared by ion-exchange.
• The activities of the catalysts were tested in Fenton-like oxidation of acetic acid.
• IE-FeZSM-5(90) was determined as the effective and stable catalyst.
• A COD reduction of 50.5% was achieved for 100 ppm acetic acid at optimum conditions.

In this study, the degradation of acetic acid was investigated by heterogeneous Fenton-like oxidation in the presence of iron-containing ZSM-5 zeolites. Iron content and Brønsted acidity of the catalyst affected positively and significantly the activity of catalyst in acetic acid (AA) degradation. The catalysts were prepared by ion-exchange method by using ZSM-5 type zeolites with different Si/Al ratio and characterized by XRD, SEM, FT-IR, ICP-AES and nitrogen adsorption measurements. The catalyst (IE-FeZSM-5 (90)) with Si/Al ratio of 42 and iron content of 8.5% (in wt) was found to be the most active catalyst in AA degradation. The influence of temperature, initial concentration of acid, amounts of H2O2 and catalyst and solution pH was investigated on degradation of AA by heterogeneous Fenton-like oxidation over this catalyst. Degradation of AA was accelerated at pH around 4 and temperature, H2O2 amount, catalyst loading and initial concentration of AA affected significantly the destruction of acid. The optimum conditions were obtained to be 0.2 g of catalyst, 333 K of temperature, solution pH of 4 and H2O2 amount of 8.35 mmol for an AA concentration of 0.1 g/dm3 with a COD removal of 50.5%. Degradation of AA obeyed first order kinetics with a rate expression of −rAA=2.56×107e−61.5/RTCAA−rAA=2.56×107e−61.5/RTCAA where −rAA in mol/dm3 min, R in kJ/mol.K, T in K and CAA in mol/dm3.

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