Eco-engineered MIL53-NH2/xanthan gum nanocomposite: a magnetic biosorbent for rapid eradication of ciprofloxacin and amoxicillin in polluted waters

Abstract

A biomagnetic nanocomposite called MIL53-NH₂/xanthan gum (MIL53-NH₂/XG–Fe₃O₄), or BMNCs, was developed as an eco-friendly material to remove pollutants from water. This new material combines the benefits of three key components: xanthan gum (XG), a natural biopolymer; iron oxide magnetic nanoparticles (Fe₃O₄), which help in easy separation using magnets; and MIL53-NH₂, a metal–organic framework (MOF) known for its porous structure and high surface area. Together, they give the BMNCs high strength, stability at high temperatures, and the ability to absorb large amounts of pollutants. The structure of the BMNCs was confirmed using various tests, including X-ray diffraction (XRD), infrared spectroscopy (FT-IR), surface charge (zeta potential), and scanning electron microscopy (SEM). The nanocomposite showed a magnetic strength of 20.82 emu g⁻¹ (from VSM analysis) and a surface area of 21.01 m² g⁻¹ (from BET analysis). BMNCs were tested for removing two common antibiotics, ciprofloxacin (CIP) and amoxicillin (AMX) from water. Tests were performed by adjusting the water pH (3–11), material amount (0.008–0.024 g), stirring time (4–24 minutes), and pollutant concentration (25–200 mg L⁻¹). Under optimal conditions, the BMNCs removed up to 237.56 mg g⁻¹ of CIP and 217.37 mg g⁻¹ of AMX, better than many traditional materials. The process followed the nonlinear Temkin model and pseudo-second-order (PSO) kinetics, indicating that chemical bonding played a major role. Thermodynamic analysis showed that the process was spontaneous and absorbed heat (endothermic). The BMNCs could be reused at least three times with little loss in performance. The proposed mechanism indicates that intermolecular interactions such as hydrogen bonding and π–π stacking, along with the porous structure of MIL-53-NH₂, contribute to the high surface area of the BMNCs, thereby enhancing the adsorption of CIP and AMX. As a result, the BMNCs present a promising solution for antibiotic removal due to their exceptional adsorption performance.