In-situ growing of metal-organic frameworks on three-dimensional iron network as an efficient adsorbent for antibiotics removal

Considering the low recyclability of powder adsorbents, an efficient method is needed to fabricate a novel three-dimensional (3D) adsorbents. Take advantage of the 3D iron network and admirable adsorption performance of the Fe-based metal-organic framework (Fe-MOF), a solvothermal method was used to in-situ growing a series of Fe-based MOFs (MIL-53(Fe) MIL-100(Fe) and MIL-101(Fe)) onto the iron network (MIL stands for Materials of Institute Lavoisier). The successful growing of MILs(Fe) on the iron network was verified by optical microscopy, SEM, XRD, FT-IR and XPS characterizations. As expected, the 3D MILs(Fe) (Fe/MILs) inherited the high adsorption capacity of powdery MILs(Fe), while excellent recycling performance was obtained. Among them, Fe/MIL-100(Fe) exhibited the highest performance towards tetracycline (TC), more than 95% of TC could be removed at fifth adsorption cycle. Mechanism indicated that the π-π and hydrogen bonding (H-bonding) interactions between Fe/MIL-100(Fe) and TC molecules played an essential role in the adsorption process. Besides, the Fe/MIL-100(Fe) adsorbent was stable in water with negligible iron leaching in solution. It is worth noting that Fe/MIL-100(Fe) kept a high adsorption performance towards TC in a wide pH range of 2–10 and suffered minor influence from the anion and humic acid in solution. Even in actual aqueous solution (tap water, river water and pharmaceutical wastewater), high performance was presented by the Fe/MIL-100(Fe) adsorbent. This work provided a new method to synthesis 3D MILs(Fe) adsorbents for wastewater remediation.