| Tetracycline is widely used in medical treatment because of its broad-spectrum antibacterial activity.However,the residue of tetracycline in the environment has seriously affected the health of the public and the balance of the ecosystem,and its pollution has aroused great concern.The efficient removal of tetracycline residue from the water environment is of great significance to the construction of an environmentally friendly society.In recent years,chromium-based metal organic framework(MIL-101)has been widely used to adsorb and remove toxic substances in aqueous solutions due to its excellent water stability and huge pore size.However,MIL-101 has limited adsorption capacity for contaminants.In order to better broaden its application range,its structural properties can be optimized by modifying MIL-101.Therefore,in this study,MIL-101 was modified by loading CuCo bimetallic nanoparticles in MIL-101 and it was used for the adsorption of tetracycline in aqueous solution.Firstly,MIL-101 was synthesized by hydrothermal method,and then Cu/MIL-101,Co/MIL-101 and a series of CuCo/MIL-101 materials were synthesized by solvent method and reduction method.These four materials were characterized by XRD,SEM,TEM,BET,FT-IR,TGA and XPS.The results showed that the materials were successfully synthesized.CuCo/MIL-101 showed the best adsorption performance for tetracycline.Compared with MIL-101,the adsorption capacity of CuCo/MIL-101 for tetracycline was increased by 140%.The increase of adsorption ability may be attributed to the chemical bond force between tetracycline molecules and Cu and Co bimetallic nanoparticles.Then,the effects of initial pH,ionic strength,humic acid and contact time on the adsorption behavior were discussed.It was found that the removal efficiency of tetracycline solution with high concentration(100 mg/L)by CuCo/MIL-101 was still as high as 82.9%.The adsorption kinetics,isothermal adsorption and thermodynamics were also studied.The results showed that the adsorption process of tetracycline by CuCo/MIL-101 was more consistent with Elovich model and Freundlich model,and the maximum adsorption capacity of tetracycline by CuCo/MIL-101 reached 225.179 mg/g.The adsorption process was spontaneous and endothermic.In addition,the mechanism of tetracycline adsorption on CuCo/MIL-101 was analyzed in detail.Finally,the regeneration experiment of the adsorbent was carried out.It was found that CuCo/MIL-101 still had high adsorption capacity for tetracycline after four adsorption-desorption experiments.The characterization of XRD,FT-IR and TEM showed that CuCo/MIL-101 had good chemical stability. |
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