Síntese de sílica mesoporosa SBA 15 funcionalizada para teste de sorção de metais pesados

Abstract

SBA-15 Mesoporous silica functionalized with amine (– NH2) hat been prepared in this work for the purpose of the development of heavy metals adsorbents from wastewater. The functionalization with organic groups has been performed by two different methods, post-synthesis and co-condensation. In this work, the matrix was prepared by co-condensation. Two organic groups were selected to be incorporated with specific reactions sites containing amino groups, cysteine (HS–CH2–CH(NH2)–COOH) and phenylisotiocianate (C6H5–NCS). The materials were characterized by X-ray Diffraction at low angle (XRD), Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM), Nuclear Magnetic Resonance Solid State (NMR), Nitrogen adsorption-desorption (BET), Thermal Analysis (TG/DTG) and Spectroscopy of the Infrared (FT-IR). The hybrid material SBA 15_NH2 exhibit BET surface area of 451 m2/g and total pore volume 0,15 cm3/g. FT-IR, NMR, TG confirmed the incorporation of organic groups, cisteine and phenylisotiocianate in the materials. The analysis indicated that all synthesized materials showed hexagonal structure, characteristic of mesoporous materials like SBA-15 with good ordering of the pores, high surface area and narrow pore size distribution. All modified samples were subjected of sorption processes of Cu+2. The maximum adsorption capacity was 21 mg/g for the material modified with phenylisotiocianate. The Langmuir isotherm model fitted well to the experimental data together of pseudo-second order model kinetic process of adsorption. The results suggest that these materials can be used as adsorbents to remove trace metal ions in contaminated aqueous systems.