Removal of lead and cadmium ions from water using primary-secondary amine modified magnetic microbeads: Equilibrium, kinetic, and thermodynamic studies

•The novel magnetic microbeads were developed based trimethoxysilylpropylethylenediamine (TSD).•Magnetic microbeads (Met-PES/ZVI) were used for the removal of lead and cadmium ions from water.•The maximum adsorption capacity was 68 mg·g−1 for Pb2+ and 51 mg·g−1 for Cd2+ was achieved.•Langmuir model best-fit R2 > 0.99 for both Pb2+ and Cd2+ ions.•Thermodynamic analysis showed that the adsorption process was physisorption. This study developed novel magnetic microbeads based on trimethoxysilylpropylethylenediamine (TSD) as a primary-secondary amine source through a one-pot process. The process involves coating magnetic iron oxide nanoparticles (MNPs) with primary-secondary amine (TSD), followed by cross-linking with alginate (Alg). The ternary magnetic microbeads (Alg@MTSD) were used to remove Pb2+ and Cd2+ ions from aqueous media. The nanocomposite was characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). Adsorption experiments were conducted under optimal conditions, and isothermal models, including Langmuir and Freundlich, as well as kinetic models, were applied to evaluate the experimental data. The findings indicated that the Langmuir model best fit the adsorption data for Pb2+ and Cd2+ ions, with R2 > 0.99. The maximum adsorption capacities were 68 mg·g−1 for Pb2+ and 51 mg·g−1 for Cd2+. Kinetic studies showed that the adsorption process followed the pseudo-second-order model. Thermodynamic analysis suggested that the adsorption mechanism was physisorption.