Sílica mesoporosa sba-15 modificada com ferro para adsorção de fosfato em águas

Abstract

Eutrophication, driven by excessive phosphate inputs into aquatic systems, demands the development of selective, stable, and cost-effective adsorbents. In this study, mesoporous silica SBA-15 was functionalized with Fe(III) ions via impregnation, yielding SBAFe(III), which was evaluated for phosphate removal from aqueous solutions. The modification increased the specific surface area from 675 to 743 m² g⁻¹ while preserving the ordered hexagonal mesoporous structure, with average pore diameters ranging from 5.4 to 5.7 nm, as confirmed by XRD, FTIR, TGA, SEM, and BET/BJH analyses. Iron loading reached saturation at 3.0 mg L⁻¹, ensuring strong anchoring of Fe(III) species onto the silica surface. Adsorption experiments revealed a maximum phosphate uptake of ~15.4 mg g⁻¹, with equilibrium achieved within 55 min. Kinetic modeling showed an excellent fit to the pseudo-first-order model (R² > 0.99), indicating that the process is predominantly governed by mass transfer from the solution to the adsorbent surface. Incorporation of Fe(III) did not compromise the structural integrity of SBA-15; instead, it enhanced specific interactions with phosphate through electrostatic complexation. These findings demonstrate that SBAFe(III) combines structural stability, moderate adsorption capacity, and regeneration potential, establishing it as a promising candidate for advanced wastewater treatment technologies aligned with the United Nations Sustainable Development Goals (SDGs), particularly those addressing water quality preservation and nutrient pollution mitigation.