Catalytic effect of Fe@Fe2O3 nanowires and Fenton process on carbamazepine removal from aqueous solutions using response surface methodology

Abstract

Carbamazepine is one of the hydrophilic compounds identified in aquatic environments. Due to toxicity and bio-stability of this psychotropic pharmaceutical in the environment and humans, its removal efficiency and mineralization are important. In this study, synthesized Fe@Fe₂O₃ nanowires were applied to improve Fenton oxidation process using FeCl₃.6H₂O and NaBH₄. The effects of different parameters such as initial pH, H₂O₂, FeSO₄.7H₂O, carbamazepine concentrations, oxidation time, and nanowires dose were evaluated using response surface methodology. After scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffract meter analysis, Fe@Fe₂O₃ morphology was synthesized in the form of nanowires with diameters of about 40-80 nm. The optimum oxidation conditions for carbamazepine were established at pH= 4.3, reaction time of 45.9 min, nanowire dose of 179.4 mg/L as well as H₂O₂, FeSO₄.7H₂O and carbamazepine concentrations of 22, 52.2 and 7.7 mg/L, respectively. The oxidation efficiency (99.5%) achieved under the optimum condition, which was determined by the model, was consistent with the efficiency predicted by the model. The multi-parameter models showed good calibration and prediction abilities with R²₌0.922, R²_adj= 0.907, R²_pred= 0.868. According to the results, the carbamazepine degradation rate increased with the increase of Fe²⁺ due to the synergistic effect between Fe@Fe₂O₃ and Fe²⁺ on the catalytic decomposition of H₂O₂and generation of OH•. It was concluded that the Fenton process based on the Fe@Fe₂O₃ nanowires can increase the carbamazepine oxidation rate in aqueous solutions. This method can also be used as an effective and pre-treatment process in the conventional treatment plants.