High-efficiency cdmium decontamination enabled by a magnetically separable ternary composite based on sustainable microcrystalline cellulose

The widespread presence of cadmium (Cd) in aquatic environments continues to pose substantial risks to ecosystem safety and public health, highlighting the urgent need for high-performance and recyclable adsorbents. In this study, a novel magnetically separable ternary composite (MCC@CaCO 3 /Fe 3 O 4 ) was successfully fabricated through a combined cooling activation and ion exchange approach, using microcrystalline cellulose as a sustainable and low-cost substrate. Comprehensive characterization techniques including XRD, FTIR, and SEM confirmed the homogeneous dispersion of Fe 3 O 4 and CaCO 3 particles on the cellulose matrix, which exhibited a developed porous structure and abundant oxygen-containing functional groups. The composite demonstrated an exceptional Cd(Ⅱ) adsorption capacity of 617.00 mg·g -1 and remarkable reusability, maintaining over 85% removal efficiency throughout twenty consecutive adsorption–desorption cycles. The adsorption process was accurately described by the Langmuir isotherm and pseudo-second-order kinetic models, with the underlying mechanism identified as a synergistic combination of ion exchange, surface complexation, and coprecipitation. This work provides a green and sustainable strategy for the effective treatment of cadmium-laden wastewater using functionalized cellulose-based materials. • A novel magnetically separable ternary composite (MCC@CaCO 3 /Fe 3 O 4 ) was successfully synthesized. • The adsorbent exhibits a high Cd(Ⅱ) adsorption capacity of 617 mg · g -1 . • The removal mechanism involves ion exchange, surface complexation, and electrostatic interactions. • The composite maintains over 85% Cd(Ⅱ) removal efficiency after 20 regeneration cycles.