Preparation and properties of magnetic superabsorbent composite based on poly (acrylic acid-acrylamide)-g-sodium alginate/Fe3O4

Abstract

Magnetic superabsorbents have been successfully synthesized through aqueous solution polymerization, employing sodium alginate as the backbone material, acrylic acid and acrylamide as the polymeric monomers, Fe₃O₄ nano-particles as the magnetic component, N,N’-methylenebisacrylamide as the crosslinking agent, and ammonium persulfate serving as the initiator. The micro-morphology and thermal stability of these superabsorbents were thoroughly characterized using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), respectively. A comprehensive investigation was undertaken to examine the swelling capacity, water retention properties, magnetic responsiveness, and reusability of the magnetic superabsorbents. The findings reveal that these superabsorbents possess an impressive maximum water absorption capacity of 302.7 g/g in distilled water. Notably, their swelling ratios maintain high levels within a pH range of 5–10. Featuring a porous structure, the magnetic superabsorbents demonstrate rapid swelling kinetics, attaining swelling equilibrium within 30 min in a 1 wt% NaCl solution. Furthermore, the superabsorbents exhibit excellent magnetic responsiveness, characterized by a maximum saturation magnetization of 7.91 emu/g, allowing for swift separation under an external magnetic field. Lastly, the magnetic superabsorbents display outstanding reusability, with their water absorption capacity in distilled water still exceeding 90% of the initial swelling ratio after seven reuse cycles.