Magnetic Hydrogel Beads as a Reusable Adsorbent for Highly Efficient and Rapid Removal of Aluminum: Characterization, Response Surface Methodology Optimization, and Evaluation of Isotherms, Kinetics, and Thermodynamic Studies.

Biopolymers such as alginate and gelatin have attracted much attention because of their exceptional adsorption properties and biocompatibility. The magnetic hydrogel beads produced and used in this study had a core structure composed of magnetite nanoparticles and gelatin and a shell structure composed of alginate. The combination of the metal-ion binding ability of alginate and the mechanical strength of gelatin in magnetic hydrogel beads presents a new approach for the removal of metal from water sources. The beads were designed for aluminum removal and fully characterized using various methods, including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, microcomputed tomography, and dynamic mechanical analysis. Statistical experimental designs were employed to optimize the parameters of the adsorption and recovery processes. Plackett-Burman Design, Box-Behnken Design, and Central Composite Design were used for identifying the significant factors and optimizing the parameters of the adsorption and recovery processes, respectively. The optimum parameters determined for adsorption are as follows: pH: 4, contact time: 30 min, adsorbent amount: 600 mg; recovery time: reagent 1 M HNO