ASSESSMENT OF THE ADSORPTION CAPACITY AND REGENERATION MECHANISMS OF HYBRID SORBENTS BASED ON LOCAL CLAY MINERALS FOR REMOVING INDUSTRIAL HEAVY METAL IONS FROM WASTEWATER

Abstract

This study evaluates the adsorption capacity and regeneration mechanisms of hybrid sorbent materials synthesized from local clay minerals for removing heavy metal ions (Pb^(2+), Cd^(2+), and Cu^(2+)) from industrial wastewater. Raw local clays—predominantly bentonite and kaolinite—were modified through functionalization with organic polymers (chitosan and polyacrylamide) and organosilanes (3-aminopropyltriethoxysilane) to enhance structural stability and active binding sites. Adsorption experiments were systematically executed under batch conditions to measure equilibrium isotherms, kinetic parameters, and thermodynamic variables. The maximum adsorption capacity (q_max) of the synthesized hybrid sorbents reached 142.5 mg/g for Pb^(2+), 98.3 mg/g for Cd^(2+), and 115.6 mg/g for Cu^(2+), significantly outperforming unmodified raw clays. Kinetic modeling confirmed that the adsorption process adheres strictly to pseudo-second-order kinetics, indicating chemisorption as the primary rate-limiting step involving ion exchange and surface complexation. Desorption and recyclability tests demonstrated that treatment with 0.1 M HCl recovered over 92% of adsorbed heavy metals, maintaining stable removal efficiency exceeding 85% through five consecutive regeneration cycles. These results prove that locally sourced clay-based hybrid composites serve as cost-effective, sustainable, and highly efficient media for industrial effluent remediation..