BDMT‐Functionalized γ‐Alumina as a High–Capacity Adsorbent for Cadmium(II): Kinetics and Isotherms

ABSTRACT

Cadmium (Cd) is a highly toxic environmental pollutant that bioaccumulates in living systems, creating severe health risks. Adsorption using functionalized materials has emerged as an effective approach for removing Cd ²⁺ from contaminated water. This study investigates the adsorption performance of thiol‐functionalized alumina composites, γ‐Al ₂ O ₃ (C)‐BDMT and γ‐Al ₂ O ₃ (S)‐BDMT. The materials were comprehensively characterized to confirm their structural and surface properties. Adsorption experiments examined the effects of initial Cd ²⁺ concentration (5–50 mg/L), pH (2–8), and contact time (0.5–40 min), under a constant adsorbent dosage of 0.005 g and fixed temperature. The optimum removal efficiency was achieved at pH 6, an initial concentration of 10 mg/L, and equilibrium times of 20–30 min. Kinetic modelling indicated that the pseudo‐second‐order model best described the adsorption process, reflecting chemisorption as the dominant mechanism. Isotherm analysis demonstrated good agreement with the Freundlich model, confirming multilayer adsorption behavior. The maximum adsorption capacities were 463.767 mg/g for γ‐Al2O3(C)‐BDMT and 428.410 mg/g for γ‐Al2O3(S)‐BDMT. These results highlight the composites’ strong potential for cadmium remediation, offering a simple synthesis route and high efficiency. Thus, the study provides valuable insight for developing effective and sustainable adsorbents for water treatment applications.