Simple Synthesis of CoNi@ZrO₂ Nanospheres for Catalytic Degradation of Chloramphenicol Under Visible Light

As a broad-spectrum antibiotic, chloramphenicol has an important contribution in resisting bacterial diseases. It has been widely used in medicine and animal husbandry, but it has the disadvantages of long-term unreasonable use and slow degradation in nature. Long-term consumption of food contaminated by chloramphenicol will cause serious side effects to human beings. Therefore, it is urgent to establish an effective method to remove chloramphenicol from wastewater. Co/Ni@ZrO₂ photocatalyst with nanosphere structure was prepared by hydrothermal method and used for the degradation of chloramphenicol (CAP).The structure, morphology and optical properties of the samples were characterized by TEM, SEM, XPS, XRD, FT-IR and UV-Vis. Under visible light, 12% Co/Ni@ZrO₂ has good photocatalytic performance for the degradation of chloramphenicol, which may be due to the synergistic effect and nano-limitation effect between Co/Ni and ZrO₂. When the optimal dosage of catalyst is 50 mg / L and the initial concentration of chloramphenicol is 20 mg / L, the degradation rate is 98.2 % within 150 min. XPS and Raman results showed that there were appropriate amount of oxygen vacancies on the surface of ZrO₂, which accelerated the electron transfer rate in the system and inhibited the recombination of photoelectron-hole pairs under visible light, thus improving the activation efficiency of dissolved oxygen in chloramphenicol solution. Free radical capture experiments showed that· O₂^-,· OH, h⁺ were the main active substances for the degradation of chloramphenicol. The possible mechanism of chloramphenicol degradation under visible light was speculated. The results show that Co/Ni@ZrO₂ is a promising photocatalyst for wastewater treatment.

A schematic diagram of charge separation and transfer during the degradation of chloramphenicol by 12wt % CoNi @ ZrO2 nanospheres