Water-based Synthesis of MIL-53(Al) at Room Temperature: An Eff ective Adsorbent for Oxytetracycline (OTC) Antibiotic Removal from Water

Abstract

MIL-53(Al), a fl exible metal-organic framework, was synthesized by a facile method through a water-based method at room temperature, aligning with the principles of green chemistry. The objective was to investigate its effectiveness in removing pharmaceuticals and personal care products (PPCPs), specifi cally focusing on oxytetracycline (OTC). Our fi ndings revealed that MIL-53(Al) possesses a structure with both micropores and mesopores, with a specifi c surface area of 916 m2/g. MIL-53(Al) notably exhibited a higher OTC adsorption capacity than commercially available powder activated carbon (PAC). The adsorption kinetics followed a pseudo-second-order model, while the Langmuir model accurately described the experimental isotherms for OTC adsorption. MIL-53(Al) outperformed previously reported MOF-based adsorbents with a maximum of 1005 mg/g capacity at pH 7. The fl exible structure induces a breathing effect that signifi cantly improves intraparticle diffusion for OTC, contributing to its adsorption effi ciency. The adsorption of OTC was infl uenced by the solution pH, the acid dissociation constants of OTC, and the charged surface of the adsorbent. Pore fi lling, hydrogen bonding, π-π interaction, electrostatic interaction, and hydrophobic interaction were all associated with the adsorptive interaction between OTC and MIL-53(Al). The MIL-53(Al) also demonstrated good regeneration and reuse, with just a little decreased adsorption capacity after three reuse cycles. These fi ndings indicate that green material MIL-53(Al) has the potential to be an effective adsorbent for removing OTC from water matrices