<![CDATA[Lead (Pb) contamination in aquatic environments poses serious risks to ecosystems and human health due to its toxicity and persistence. This study evaluates the potential of Gamalama volcanic soil (GVS), a locally abundant aluminosilicate material, as a low-cost adsorbent for Pb(II) removal. Batch adsorption experiments were conducted at initial Pb(II) concentrations of 50–500 mg/L and contact times of 20–120 min. Adsorption behavior was analyzed using kinetic models, namely the pseudo-first-order and pseudo-second-order models, and isotherm models, namely the Langmuir and Freundlich models. The structural and surface properties of GVS before and after adsorption were characterized by FTIR, XRD, and N₂ adsorption (BET). The adsorption efficiency decreased from 45.8% to 33.6% with increasing initial Pb(II) concentration, indicating progressive saturation of active sites. In contrast, adsorption increased with contact time and reached a maximum of 94.87% at 60 min. Kinetic analysis showed an excellent fit to the pseudo-second-order model (R² = 0.9997), suggesting a chemisorption-controlled process. The Freundlich isotherm provided a better fit (R² = 0.9902), indicating multilayer adsorption on heterogeneous surfaces. XRD patterns showed no significant changes after adsorption, while the BET surface area decreased from 490.128 to 464.707 m²/g, suggesting partial pore blockage. These results demonstrate that GVS is a promising natural adsorbent for Pb(II) removal, although further studies on selectivity and regeneration are required for practical applications.]]>
