Effective removal of Rhodamine B dye using novel benzoxazine-crosslinked magnetic chitosan

Water pollution and dye contamination pose serious environmental challenges, necessitating the development of efficient and sustainable adsorbent materials. In this study, we report a novel magnetic Chitosan-based nanocomposite synthesized by functionalization with 2-hydroxy-1,4-benzoxazine, glutaraldehyde crosslinking, and Fe₃O₄ incorporation Ch-BOX/Glu/Fe₃O₄ for the removal of Rhodamine B dye. Comprehensive characterization FTIR, HNMR, XRD, SEM, TEM, TGA, EDX confirmed the successful modification, with Fe₃O₄ particle size of 10.4 nm and enhanced thermal stability T₅₀ = 420 °C. Under optimized conditions 0.5 g adsorbent dose, 20 mg/L initial dye concentration, 25 °C, 3 days, the maximum dye removal efficiency reached 81.3 % for Ch-BOX/Glu and 79.7 % for Ch-BOX/Glu/Fe₃O₄. Kinetic analysis revealed that the adsorption followed a pseudo-second-order model R² = 0.99, confirming chemisorption. Reusability tests demonstrated that Ch-BOX/Glu retained 60 % removal efficiency after 3 cycles, while Ch-BOX/Glu/Fe₃O₄ retained 35 %, indicating comparatively higher long-term stability for the non-magnetic composite. This work introduces an innovative Chitosan-benzoxazine-magnetite hybrid platform that combines structural stability, efficient dye removal, and recyclability, highlighting its potential for future wastewater treatment applications.