Abstract
The adsorptive potential has been evaluated for the aminopropyl functionalized mesoporous silica materials obtained by co-condensation and post grafting methods. Nitrogen sorption, small angle neutron and X-ray scattering (SANS and SAXS) demonstrated high surface area and well-ordered hexagonal pore structure suitable for applications as adsorbents of metals from waste waters. A comparison of Cr(VI) adsorption properties of the materials prepared by different functionalization methods has been performed. The obtained results demonstrated the adsorption capacity due to the affinity of the chromium ions to the amino groups, and showed that co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTES) resulted in higher metal sorption capacity of the materials compared to post-synthesis grafting of aminopropyl groups onto the mesoporous silica particles.
Highlights
Decontamination of toxic pollutants by porous nanomaterials with high removal efficiency became a topic of intense studies in recent years [1]
The morpho-structural and adsorption properties of mesoporous silica functionalized with aminopropyl triethoxysilane (APTES) by the co-condensation and the post grafting methods were evaluated
From the performed studies it was found that adsorption capacity of Cr(VI) was almost ten times higher for the material prepared by co-condensation compared to the one prepared by post-grafting
Summary
Decontamination of toxic pollutants by porous nanomaterials with high removal efficiency became a topic of intense studies in recent years [1]. The direct method permits preparation of organic-inorganic hybrid materials in a short time and involves a one-step co-condensation between tetraalkoxy silanes with one or more organoalkoxy silanes through the sol-gel process without or in the presence of a structure directing agent [7] The advantages of this method are that it gives a more homogeneous distribution of the functional groups but the disadvantage is that it produces materials with a less ordered structure [8,9]. The post grafting method uses a two-step procedure: synthesis and functionalization are done at separate stages, it is easier to control particle size, morphology, pore diameter [10], and pore ordering Usually it produces nonuniformly distributed organic groups, which can congregate on the particle external surface blocking the pore entrance [8,11,12]. Some interesting differences between the pore morphologies of ordered mesoporous silica prepared by co-condensation and post grafting of organic functional groups have been revealed in previous publications [14,15,16]
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