Application of the Swan Model for the Adsorption of Ni<sup>2+</sup> and Cd<sup>2+</sup> on Chitosan Derivative in a Packed Bed Column

Water pollution by heavy metals constitutes a significant environmental and health risk, necessitating efficient and reusable adsorbents. The current study investigates the application of inexpensive biopolymer chitosan to extract Ni 2+ and Cd 2+ ions from aqueous solutions. Material characterization using X-ray diffraction (XRD) showed the amorphous nature (absence of peak at 10°), and Brunauer-Emmett-Teller (BET) analysis exhibited the mesoporous surface area of 302.12 m 2 /g, suitable for the adsorption of metal ions. The Swan model was parameterized with batch-derived adsorption parameters (i.e., Qₘₐₓ = 220 mg/g for Ni 2+ , 226 mg/g for Cd 2+ ) and successfully predicted packed-bed breakthrough curves at optimum pH (7 for Ni 2+ , 6 for Cd 2+ ), with transport rates of 3.65 × 10 -11 m 2 /s (Ni 2+ ) and 3.14 × 10 -11 m 2+ /s (Cd 2+ ) for a 1.2 m column. The material retained over 95% removal efficiency after five regeneration cycles. These findings show the potential of chitosan for large-scale water treatment with high efficiency, model-driven design, and strong reusability.