Optimized Arsenic Adsorption Using Functionalized Mesoporous Silica: Insights into Kinetics, Thermodynamics, and pH-Dependent Behavior

Abstract

This study investigates the preparation and effectiveness of functionalized mesoporous materials, amino-functionalized SBA-15 and mercapto-functionalized SBA-15, for arsenic removal, specifically targeting As(III) and As(V) species. Characterization through BET analysis revealed significant differences in surface areas and pore structures between unmodified SBA-15 and the functionalized materials. Adsorption experiments demonstrated that the Langmuir isotherm model best described the equilibrium data, with maximum adsorption capacities reaching 98.3 mg/g for M-SBA-15 with As(V) and 97.3 mg/g for A-SBA-15 with As(III). The adsorption kinetics followed a pseudo-second-order model, indicating rapid saturation of active sites at lower arsenic concentrations. Thermodynamic parameters suggested that adsorption processes were spontaneous and endothermic, with positive \(\Delta\)S⁰ values indicating increased randomness at the interface. Notably, pH strongly influenced the adsorption performance, with optimal adsorption observed near neutral pH for both As(III) and As(V). These findings underscore the potential of M-SBA-15 and A-SBA-15 as promising adsorbents for arsenic removal from water. This study highlights the critical need for advanced materials to address global water contamination challenges and underscores the potential of M-SBA-15 and A-SBA-15 as highly efficient adsorbents for arsenic remediation.