Novel functionalized metal-organic framework MIL-101 adsorbent for capturing oxytetracycline

Developing high-performance materials for removal of antibiotics has attracted ever-increasing concerns since variety of harmful antibiotics have been frequently detected in aquatic environments and posed a serious threat to both human health and ecosystems in recent years. In this work, a novel adsorbent (ED-MIL-101) for oxytetracycline antibiotic (OTC) was prepared by grafting ethylenediamine (ED) to Lewis acidic open metal sites in porous metal-organic framework MIL-101. The successful grafting was corroborated via FT-IR spectrum. Compared with the pristine MIL-101, ED-MIL-101 demonstrated a slight decrease in BET surface areas and pore sizes, while the basic frameworks remain invariant. Results for kinetics and thermodynamics showed that the aminofunctionalized adsorbent exhibited a predominant superiority over nongrafted MIL-101 and activated carbon (AC) on the removal of OTC, even though the specific surface area decreased remarkably after grafting. Moreover, ED-MIL-101 can be regenerated by simple washing with ethanol and reusable up to at least the third run with little change in adsorption capacity. Evidence from zeta potential showed that the adsorption of OTC was also driven by electrostatic interaction between the OTC and ED-MIL-101. These results indicate that ED-MIL-101 has great potential in removing OTC contaminant from water.