A Magnetically Recyclable Carboxymethyl Chitosan-based Hydrogel as a High-Capacity Adsorbent for Malachite Green Dye from Aqueous Solutions
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A novel magnetic carboxymethyl chitosan/polyacrylic acid (Fe 3 O 4 /CMC/PAA) hydrogel adsorbent was successfully synthesized via free radical polymerization for malachite green (MG) dye removal from wastewater. Comprehensive characterization through FT-IR, XRD, SEM, and VSM confirmed its porous network structure containing abundant functional groups (-OH, -COOH, -NH₂) and superparamagnetic properties (1.8 emu/g saturation magnetization). The adsorbent exhibited optimal performance at pH 10, achieving a maximum adsorption capacity of 397.73 mg/g. The adsorption mechanism followed pseudo-second-order kinetics and the Langmuir isotherm model, indicating chemically controlled monolayer adsorption. Thermodynamic analysis revealed the spontaneous (ΔG < 0) and endothermic (ΔH > 0) nature of the process. After five regeneration cycles, the material maintained 86.7% removal efficiency, demonstrating excellent reusability. This magnetic hydrogel combines high adsorption capacity with rapid magnetic separation capability, offering significant potential for practical dye wastewater treatment applications. The integrated properties of efficient contaminant removal, facile recovery, and stable regeneration performance position it as a promising alternative to conventional adsorbents.
