Efficiency and Selectivity Study of Eco‐Extracted Chitosan for Potentially Toxic Elements Removal From Brassware Effluents

This study investigated the efficiency of eco-extracted chitosan obtained through a microwave-assisted method for removing potentially toxic elements from synthetic solutions and industrial effluents. The obtained results disclosed that the removal efficiency of metal ions depends on several parameters, including contact time, adsorbent dose, deacetylation degree of chitosan, initial metal ion concentration, and solution pH. Kinetic analysis showed that the adsorption process follows a pseudo-second-order model, suggesting that the chemisorption mechanism dominates the adsorption process. Additionally, equilibrium data fitted well with the Langmuir isotherm, indicating monolayer adsorption with a homogeneous adsorbent surface and limited binding sites. Maximum adsorption capacities were 31.78 mg/g for Ag⁺, 30.57 mg/g for Cu²⁺, 14.49 mg/g for Ni²⁺, and 37.21 mg/g for Pb²⁺. Thermodynamic analysis revealed that the adsorption of Ag⁺, Cu²⁺, and Pb²⁺ occurs spontaneously across all temperatures, whereas the adsorption of Ni²⁺ is non-spontaneous, implying that Ni²⁺ removal is less favorable. Regarding desorption, although studies show a slight decrease in efficiency over successive cycles, chitosan remains a highly reusable material, especially for metals like Ag⁺ and Pb²⁺. To assess the treatment performance on real brassware effluent, two types of wastewater were analyzed: a single-metal effluent containing only Ni²⁺, and a multi-metal effluent comprising Ag⁺, Cu²⁺, and Ni²⁺. The adsorption capacity for Ni²⁺ increased to approximately 56 mg/g, demonstrating the high chitosan efficiency in treating complex effluents brassware. In the multi-metal system, monovalent ion Ag⁺ was preferentially adsorbed over divalent ions, indicating selective adsorption behavior. The results obtained highlight the potential of eco-extracted chitosan as a sustainable and eco-friendly adsorbent for the removal of potentially toxic elements from industrial effluents.