Metal-organic framework decorated by chitosan implemented as an efficient solid phase extraction of antibiotics residues from milk

The increased prevalence of antibiotic residues in milk causes serious health and environmental concerns, to necessitate the development of effective and safe removal techniques. With the aim of demonstrating a model for environmental remediation, this study focuses on exploiting a Ca-based metal–organic framework (Ca-MOF) integrated with chitosan for the highly efficient removal of sulfamethazine and sulfanilamide from milk. Chitosan was cross-linked with Ca-MOF through bridge of epichlorohydrin (EPH). The obtained Ca-MOF@Chitosan composite were exhibited with exceptional adsorption capacities, reaching 251.8 mg/g and 194.3 mg/g for sulfamethazine and sulfanilamide, respectively. The removal efficiency under realistic milk conditions followed pseudo-second-order kinetics with high affinity toward the antibiotics, and the experimental data were best described by the Langmuir isotherm model. The improved adsorption of sulphonamides onto composite is governed by a combination of chemisorption and physical interactions presented in H-bonding, π–π, electrostatic interactions, as well as pore filling. Almost complete antibiotic recovery from Ca-MOF@Chitosan was achieved within 1 h using ethanol, while the material exhibited good stability and reusability. The synergistic combination of the high surface area and porosity of Ca-MOF with the biocompatibility of chitosan yields a promising green adsorbent for environmental remediation and solid-phase extraction, demonstrating effective capability for antibiotic detection.