Ultrasound-Assisted Removal of Tetracycline by a Fe/N-C Hybrids/H2O2 Fenton-like System

In this work, the degradation of tetracycline (TC) in water by the integrated ultrasound (US)-Fenton process was investigated. For this, a new composite Fe/N-C-x (x is the molar ratio of iron salt Fe(NO3)(3)center dot 9H(2)O) catalyst was synthesized through simple carbonization of the mixture of glucose and iron salt Fe(NO3)(3)center dot 9H(2)O) in the presence of ammonium chloride as the nitrogen source. The resultant catalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, and N-2 adsorption-desorption, showing a typical graphite porous structure and good magnetic properties. The results indicated that the optimized Fe/N-C-2 catalyst prepared with a mole ratio of glucose/Fe(NO3)(3)center dot 9H(2)O)/NH4Cl of 5:2:16.8 exhibited the highest TC removal in the Fe/N-C-2/H2O2/US system at a wide pH range from 3.0 to 11.0. At an initial pH of 7.0, TC removal in the Fe/N-C-2/H2O2/TC/US system was 1.83, 18.69, and 28.75 times of that in Fe/N-C-2/TC/H2O2, H2O2/TC/US, and TC/H2O2 systems, showing a positive synergistic action between US and Fe/N-C-2. The effects of catalyst dosage, H2O2 concentration, ultrasonic power, humic acid, and coexisting anions on TC removal were investigated. The preliminary analysis suggested that the Fe-N species and the graphite N dispersed in the carbon matrix are responsible for the efficient catalytic activity. By a simple magnetic separation, the Fe/N-C-2 catalyst was easily recovered and used for the next degradation experiment. Above 88% catalytic ability of Fe/N-C-2 was retained even after six successive runs, suggesting its good reusability. The simple preparation strategy, good magnetic property, and good catalytic ability of the Fe/N-C-2 materials make them promising alternative Fenton-like catalysts for the antibiotics abatement in water.