Eco-Friendly Chitosan-Based Composite for Superior Pb²⁺ Adsorption: Mechanism and Performance İnsights

The presence of Pb²⁺ ions in water systems poses severe environmental and public health hazards, highlighting the need for efficient and sustainable treatment technologies. Among various remediation approaches, adsorption stands out due to its practicality and cost-effectiveness; however, selecting environmentally benign, highly efficient, and low-cost adsorbents remains a key challenge. In this work, composite beads of the biopolymers chitosan (Ch) and alginate (A) were synthesized to address this need. After synthesis, the structural characteristics of the Ch–A beads were examined, and their adsorption performance toward Pb²⁺ ions was systematically evaluated under varying operational parameters. The results indicated that the composite beads removed Pb²⁺ ions efficiently while maintaining structural stability. The adsorption mechanism was governed mainly by chemical interactions, and the composite achieved a maximum adsorption capacity of 279 mg g⁻¹. Thermodynamic and kinetic analyses confirmed that adsorption occurred via endothermic and spontaneous processes and was controlled by multiple pathways, including pore and film diffusion. Overall, these findings demonstrate that Ch–A composite beads provide a scalable, environmentally sustainable, and regenerable adsorbent material suited for removing Pb²⁺ ions from contaminated water.