Magnetic alginate/glycodendrimer beads for efficient removal of tetracycline and amoxicillin from aqueous solutions

The release of antibiotic drugs into aquatic environments is a serious environmental and health problem in recent years. Therefore, the development of potential adsorbents for the effective removal of tetracycline (TC) and amoxicillin (AMX) of aqueous media is of great importance. In this study, new alginate beads were successfully prepared by encapsulation of Fe₃O₄@maltose-functionalized triazine dendrimer in alginate (Alg/Fe₃O₄@C@TD) for the first time. The obtained beads were utilized as a well adsorbent for the removal of TC and AMX antibiotics from aqueous solutions by batch adsorption procedure. The characteristics of the synthesized beads were investigated using FT-IR, Zeta potential, SEM, XRD, EDX, VSM, and BET. The effects of various operation factors such as adsorbent dose, pH of the solution, contact time, antibiotic initial concentration, temperature, and ionic strength on the removal of antibiotics were studied. Moreover, Langmuir and Freundlich adsorption isotherm results showed that the Langmuir model fitted well for the adsorption of both antibiotics onto Alg/Fe₃O₄@C@TD beads. Based on the Langmuir model, the maximum adsorption capacity of TC and AMX onto Alg/Fe₃O₄@C@TD beads at 25 °C was 454.54 and 400 mg/g, respectively. Kinetic and thermodynamic studies also indicated that the TC and AMX adsorption were found to be well fitted with a pseudo-second-order kinetic model, feasible, endothermic, and spontaneous in nature. In addition, the Alg/Fe₃O₄@C@TD beads showed excellent reusability for removal from both antibiotics after six adsorption cycles. Overall, the obtained results suggest that Alg/Fe₃O₄@C@TD beads could be considered as a low-cost and eco-friendly adsorbent for antibiotic contaminants removal from aquatic media.