(1) 东南大学能源与环境学院

The nano-Mg(OH)_2 with different morphologies was prepared by the chemical precipitation using magnesium chloride and natural bischofite obtained from the Qarhan Salt Lake as the raw material, respectively. The surface morphology, crystal structure and surface functional group of the synthesized catalysts were characterized by scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy. The obtained materials were firstly used for the catalytic ozonation process. The degradation and mineralization of metronidazole by two nano-Mg(OH)_2 catalysts [Mg(OH)_2-1 and Mg(OH)_2-2] with different morphologies were investigated. The results showed that the degradation and mineralization efficiency of metronidazole in the single ozonation process within 10min reached 51.9% and 17.4%, respectively. The addition of Mg(OH)_2-1 or Mg(OH)_2-2 into the ozonation system caused a significant improvement for the removal and mineralization efficiency of metronidazole. The catalytic ozonation performance of Mg(OH)_2-2 was better than that of Mg(OH)_2-1. The pseudo-first order kinetic model had a good fitness (R2>0.97) for the removal of metronidazole in the single ozonation process, Mg(OH)_2-1 catalytic ozonation process and Mg(OH)_2-2 catalytic ozonation process. In addition, the stability and reusability of these two different nano-Mg(OH)_2 catalysts were also evaluated. The results indicated that these two nano-Mg(OH)_2 still maintained high metronidazole removal efficiency even after six repeated runs. Therefore, the synthesized nano-Mg(OH)_2 with different morphologies will be a promising ozonation catalyst for the removal of antibiotics.