Carbon-Coated Multifunctional Magnetic Nanoparticles for Fluorescent Detection and Removal of β‑Lactam Antibiotics...

The present study addresses the design of an innovative magneto-luminescent nanocomposite by coating cobalt ferrite nanoparticles with an organic layer, enhancing their multifunctional properties. Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS) analyses confirm the successful formation of an organic layer rich in functional groups, including hydroxyls, carbonyls, and amines. These groups influenced the surface charge, resulting in positive ζ-potential at acidic pHs and negative ζ-potential at alkaline ones. Nitrogen adsorption measurements and Brunauer-Emmet-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses revealed a decrease in surface area but an increase in pore size and volume. The nanocomposite particles exhibited a 26% increase in magnetization at room temperature compared to that of cobalt ferrite, attributed to their larger size. Additionally, the organic coating conferred luminescent properties, enabling the detection of β-lactam antibiotics, as evidenced by luminescence enhancement. For amoxicillin, a detection limit of 26 μmol/L (0-500 μmol/L) was determined. The adsorption kinetics experiments conducted with 0.2 g of the nanocomposite per liter of solution with contaminant at room temperature and pH 6.8 indicate that the process follows a pseudo-second-order (PSO) model (q _e = 149.4 ± 0.4 mg·g^-1). The thermodynamic tests indicate that the interaction between the nanocomposite and amoxicillin is spontaneous at low temperatures. Finally, the nanocomposite demonstrated the dual capability of detecting and magnetically removing amoxicillin from aqueous solutions, highlighting its potential for environmental remediation applications.