Bimetallic Fe/Co-MOFs for tetracycline elimination

Fe/Co metal–organic frameworks (Fe/Co-MOFs) were synthesized by a solvothermal method using terephthalic acid (BDC) and N,N-dimethylformamide (DMF), and the removal of tetracycline (TC) was accomplished with high efficiency. We explored the influence of Co content on the characteristics of the bimetallic MOFs. The structures of the Fe/Co-MOFs were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and nitrogen physisorption analysis. The results showed that Co2+ was well loaded in the Fe-MOFs. Due to the different coordination behaviors of Co2+ and Fe3+ with BDC, the Fe/Co-MOFs formed a new 3D structure with a spike ball-like morphology. The morphology changed dramatically, leading to a large specific surface area, and the activity of the Lewis acid sites was greatly enhanced. Through FTIR and XPS analysis before and after adsorption, the adsorption process was mainly affected by coordination action. The largest TC adsorption capacity was observed when the Fe/Co ratio was equal to 1:3, and the saturated adsorption capacity was 139.8 mg g−1.Graphical abstract