Surface‐Engineered TiO 2 Nanoparticles for Sustainable Cadmium Adsorption From Aqueous Acidic Medium
Abderraouf Jraba, Amel Chibani, Chirine AOUALI, Khaled Brahmi, Wided Bouguerra, Elimame ElalouiABSTRACT
Pure and functionalized TiO 2 were successfully synthesized via Stober‐modified sol–gel. TEM and HRTEM confirmed the nanometric morphology and structural modifications induced by functionalization. The average particle sizes were 17.55 nm for pure TiO 2 , 25.1 nm for NH 2 ‐ TiO 2 , and 19.39 nm for SH‐TiO 2 . EDX, FTIR, and CHNS elemental analysis validated the successful of grafting on TiO 2 surface. BET surface analysis revealed high specific surface areas of 394.70, 260.19, and 317.47 m 2 ·g −1 for TiO 2 , NH 2 ‐TiO 2 , and SH‐TiO 2 , respectively. This decreases after functionalization attributed to partial pore blocking by grafted organosilanes. Measured pH PZC decreases after functionalization, suggesting the increase of cations adsorption in acidic medium. The adsorption performance of nanoparticles was studied for Cd 2+ removal from acidic aqueous media. Amine and thiol functionalization improve the adsorption efficiency relative to pure TiO 2 to reach ∼15mg·g −1 for NH 2 –TiO 2 , and ∼26mg·g −1 for SH–TiO 2 attributed to strong Cd 2+ ‐amin and Cd 2+ ‐sulfur affinities. Adsorption equilibrium data were fitted using Langmuir, Freundlich, and Dubinin–Radushkevich models, suggesting monolayer adsorption on energetically homogeneous sites, surface heterogeneity, and a predominantly physisorption mechanism, with a feature of chemisorption approach for thiol‐modified samples. These results demonstrate that surface‐functionalized TiO 2 are promising adsorbents for efficient Cd 2+ remediation in highly acidic wastewater systems.