Adsorption of sulfamethoxazole antibiotic from aqueous media using thermally activated UiO-67 metal-organic framework

Abstract

Sulfamethoxazole (SMX) has increasingly emerged as an emerging contaminant due to its environmental persistence, potential biotoxicity, and contribution to the development of antibiotic resistance. This study investigated the adsorption efficiency of SMX onto the Universitetet i Oslo-67 (UiO-67) metal-organic framework (MOF). UiO-67 was synthesized using a solvothermal method with thermal activation (A-UiO-67). X-ray diffraction (XRD), Fourier transform infrared (FTIR), N2 adsorption-desorption, and scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS) and elemental mapping analyses were performed to investigate the crystal structure, functional groups, morphology, elemental composition, and surface area of the A-UiO-67. The synthesized adsorbent showed a microporous structure, a large BET surface area (2097.71 m2/g), and good crystallinity and reusability. Kinetic adsorption studies indicated that SMX adsorption onto A-UiO-67 followed a pseudo-second-order kinetic model, suggesting that the adsorption rate is primarily governed by chemical interactions between SMX molecules and active sites of the A-UiO-67 surface, rather than by mass transfer or diffusion. The findings reveal high adsorption capacity (103.2 mg/g) when the adsorption dosage is 200 mg/L and the initial SMX concentration is 50 mg/L within 60 min of contact time. Among the three adsorption isotherms (Langmuir, Freundlich, Temkin models) the Freundlich (0.98) and Temkin (0.95) models best fit the studies. This study highlights the promising potential of thermally activated MOFs as an effective adsorbent for antibiotics in wastewater treatment and environmental remediation.