La/LaF3 co-modified MIL-53(Cr) as an efficient adsorbent for the removal of tetracycline

Chromium based metal-organic framework (MIL-53(Cr)) has enormous potential in the removal of organic contaminants from aqueous solutions due to its outstanding water stability, whereas its poor adsorption capacity limits the application. In this study, La/LaF3-MIL-53(Cr) was successfully synthesized by taking the advantages of La doping and LaF3 encapsulation with one-step hydrothermal method. Diverse analysis tools were utilized to verify that La not only existed in the framework, but also was loaded in the pores in the form of LaF3. The adsorption experiment results demonstrated that 0.3-La/LaF3-MIL-53(Cr) exhibited significantly improved adsorption capacity by four times compared with the pristine MIL-53(Cr) material. XPS and FTIR revealed that the affinity of La to tetracycline was significantly stronger than that of Cr and the excellent dispersion of LaF3 in the material may also be the cause of the increase in adsorption capacity. This study described a simple method to combine two different forms of modification and the modified material was potential for tetracycline adsorption. [Display omitted] •MIL-53(Cr) was modified by combining doping and encapsulation for the first time in the process of in-situ synthesis.•The adsorption capacity of 0.3-La/LaF3-MIL-53(Cr) increased by four times compared to MIL-53(Cr).•The better adsorption performance was ascribed to the stronger affinity of La to tetracycline than that of Cr.•The excellent dispersion of LaF3 in the material may also be the cause of the increase in adsorption capacity.