FeOOH-CoFe layered double hydroxide carbon felt cathode for the electro-Fenton degradation of oxytetracycline in aqueous solution.

Abstract

Heterogeneous electro-Fenton is one of green and promising technologies for removing organic pollutants. In this paper, the FeOOH-CoFe layered double hydroxide carbon felt (LDH/CF) was synthesized by a facile hydrothermal method for an efficient degradation of oxytetracycline (OTC). The structural morphology and elemental composition of the composite electrode were studied by scanning electron microscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. Then, the electrocatalytic activity of the composite electrode was analysed through electrochemical characterization such as cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. The removal rate of 20 mg/L OTC reached about 91.6% at pH = 3, with a current density of 6.67 mA cm^-2 within 60 minute in the hydrophobic FeOOH-CoFe LDH/CF + PTFE system. Moreover, the catalytic electrode exhibited impressive degradation efficiency over a wide pH range. According to quenching experiments, the principal reactive oxygen species (·O₂^-, ·OH, and ¹O₂) involved in the degradation of OTC was identified. Based on this discovery, the possible mechanism for the degradation of OTC was also proposed. In addition, the cyclic experiment demonstrated relatively excellent stability of the hydrophobic FeOOH-CoFe LDH/CF + PTFE electrode, which provided the possibility for the practical application of the electrode.