Removal of Cu(II) from Aqueous Medium Using Chitosan/nSiO₂ Nanocomposite: Fixed-Bed Adsorption Study and Modeling

The study aims to use Chitosan/nSiO₂ Nanocomposite (CSNC) as an adsorbent to eliminate toxic Cu(II) ions from its aqueous solution using a fixed-bed continuous column system. nSiO₂ was synthesized from rice husk ash. The adsorption investigations were performed at optimum pH 6.5 under different operating conditions, such as bed height (3–7 cm), influent flow rates (30–50 mL min⁻¹), and influent Cu(II) concentration (10–30 mg L⁻¹). The removal of Cu(II) was increased with the column’s bed depth but reduced with flow rate and adsorbate concentration. Experimental observations were employed to study seven kinetic models. The Thomas model was confirmed to be the best-fit kinetic model corresponding to 3 cm bed height, a column diameter of 1.5 cm, 30 mL min⁻¹ flow rate, and an initial metal concentration of 30 mgL⁻¹. A regeneration study and scale-up design were also reported. MLR (R² > 0.98) and GA techniques (R² = 1) were also applied to forecast the elimination of Cu(II). The performance of the prepared nanocomposite adsorbent was evaluated on a laboratory scale for removing Cu(II) from synthetic wastewater. This study integrates sustainability and circular economy principles in the application of adsorbents by focusing on their synthesis, utilization in fixed-bed continuous column systems, regeneration, and safe disposal.