In situ embedding of Fe3O4 into large-lateral graphene oxide with chitosan for enhanced sulfonic dyes removal

This study presents a novel ternary magnetic composite (CS-Fe₃O₄-GO), synthesized by electrochemical exfoliation of large-lateral graphene oxide (GO) sheets, in situ embedding of Fe₃O₄ nanoparticles, and glutaraldehyde cross-linking with chitosan (CS). The composite effectively prevents GO restacking and enhances Fe₃O₄ dispersion, which increases interlayer spacing and exposes more active sites, thereby improving adsorption performance. The optimized composite demonstrated remarkable adsorption capacities of 1201 mg/g for Acid Fuchsin (AF) and 1135 mg/g for Amaranth (AM). Kinetic analysis revealed that adsorption was primarily governed by chemisorption, with physisorption also contributing to the overall process. Isotherm analysis fitted the Freundlich model, indicating multilayer adsorption on heterogeneous surfaces. The composite exhibited high selectivity in the presence of 10,000 mg·L⁻¹ of coexisting ions (e.g., NO₃⁻, SO₄²⁻, Cl⁻) and maintained efficient adsorption across a broad pH range (3−10). Furthermore, adsorption performance remained stable in tap and lake water, with only a slight decrease observed in industrial wastewater, demonstrating its practical applicability. Synergistic mechanisms including hydrogen bonding, electrostatic interactions, and π–π stacking contribute to the strong dye adsorption. This research highlights the potential of CS-Fe₃O₄-GO-10 as an eco-friendly, high-performance adsorbent, offering a sustainable solution for addressing critical water pollution challenges in industrial applications.