Optimal adsorption of pefloxacin antibiotics from aqueous solutions: Improved performance with metal-organic framework MIL-101(Cr)

Abstract

The widespread use and subsequent release of antibiotics by humans and animals pose health and environmental risks, compelling their removal from aquatic ecosystems. MIL-101(Cr), a metal-organic framework (MOF), exhibits versatile applications in antibiotic adsorption owing to its exceptional structural characteristics. In this context, MIL-101(Cr) nanoparticles are successfully prepared via the hydrothermal method to remove pefloxacin (PEF) from aqueous solutions. The resulting MIL-101(Cr) adsorbents showcase high crystallinity (97.6%), a large surface area (3166 m2/g), broad nanopore sizes, good thermal stability, and efficient reusability. Factors including initial PEF concentration, pH, dosage of adsorbent, and temperature are thoroughly investigated. The findings reveal a good adsorption capacity (254.3 mg/g) with an optimal removal efficiency (99.7%) at 308 K in a neutral pH of 7.0 when the adsorbent dosage is 250 mg/L and the initial PEF concentration is 200 mg/L within 80 min of contact. Among the three adsorption isotherms (Langmuir, Freundlich, Temkin models), the Langmuir equation best fits the studies, indicating a maximum adsorption capacity of 253.8 mg/g at 25°C, while the experimental equilibrium adsorption capacity is 229.2 mg/g at the same temperature. Adsorption kinetics aligns with the pseudo-second-order model. Thermodynamic parameters and activation energy affirm the endothermic and spontaneous behavior of the adsorption process, attributed to both physisorption and chemisorption. This study highlights the promising potential of synthesized MOF nanocrystals as an effective adsorbent for antibiotics in wastewater treatment and environmental remediation.