Comparative characteristics of texture and properties of hybrid organic–inorganic adsorbents functionalized by amine and thiol groups |
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Authors: | Yuriy L. Zub Inna V. Melnyk Nataliya V. Stolyarchuk Halyna I. Dobryanska Mariusz Barczak Andrzej Dabrowski |
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Affiliation: | aInstitute of Surface Chemistry, NAS of Ukraine, 17 General Naumov Street, Kyiv 03164, Ukraine bFaculty of Chemistry, Maria Curie-Sklodowska University, pl. M.Curie-Sklodowskiej 2, 20-031 Lublin, Poland |
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Abstract: | The structure and texture characteristics of the hybrid organic–inorganic adsorbents, which were obtained by using of two-component systems of “structure-forming agent/trifunctional silane”, are compared as follows: the first component is Si(OC2H5)4 or (C2H5O)3Si–A–Si(OC2H5)3, where A = –(CH2)2– or –C6H4–; the second one is alkoxysilane with amine (–NH2, NH, –NH(CH2)2NH2) and thiol (–SH) groups. The adsorbents, derived from TEOS, have more accessible functional groups (2.6–4.2 mmol/g) than xerogels, which are based on bis(triethoxysilanes) (1.0–2.6 mmol/g). On another hand xerogels derived from bis(triethoxysilanes) have a more extended porous structure (Ssp =516–968 m2/g, Vs = 0.418–1.490 cm3/g, d = 2.5–15.0 nm) than those that are based on TEOS (Ssp = 4–631 m2/g, Vs = 0.005–1.382 cm3/g, d = 2.3–17.7 nm). The geometric dimensions of functional groups have a more essential effect on the parameters of porous structure in the case of TEOS-derived xerogels. Using solid-state NMR spectroscopy, it has been shown that in synthesis of xerogels with the use of TEOS, the molecular frame of globules is formed by structural units Qn (n = 2,3,4), and the functional groups exist as structural units of Tn (n = 2,3). The xerogels obtained with using bis(triethoxysilanes) consist only of structural units of Tn-type (n = 1,2,3). |
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