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1
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Silica synthesis by the sol-gel method and its use in the preparation of multifunctional biocomposites

100%
Klapiszewski Ł., Królak M., Jesionowski T.
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issue 2
173-184
EN
This study focuses on the optimization process of silica synthesis using the sol-gel method while applying a statistical design of experiments which was based on a multilevel mathematical model. The product obtained in the process of optimized synthesis, characterized by the best dispersive and morphological parameters, was used for the preparation of organic/inorganic composites. The organic precursor was Kraft lignin, a high-molecular natural polymer. Synthesis of silica/lignin biocomposites was carried out by three proposed methods. The physicochemical properties and dispersive-morphological properties of each product were determined using the following available methods: Scanning Electron Microscopy - SEM, Non-Invasive Back-Scattering - NIBS, Fourier Transform Infrared Spectroscopy - FT-IR, Thermogravimetric analysis - TG and others. The electrokinetic and thermal properties of the biocomposites sufficed to be applied for example, as a cheap and biodegradable polymer filler. Further areas of application of these composites were sought, especially in electrochemistry as the advanced electrode materials.
2
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Silica/lignosulfonate hybrid materials: Preparation and characterization

100%
Klapiszewski Ł., Zdarta J., Szatkowski T., Wysokowski M., Nowacka M., Szwarc-Rzepka K., Bartczak P., Siwińska-Stefańska K., Ehrlich H., Jesionowski T.
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issue 6
719-735
EN
The research reported here concerns the synthesis, characterization and potential applications of silica/lignosulfonate hybrid materials. Three types of silica were used (Aerosil®200, Syloid®244 and hydrated silica), along with magnesium lignosulfonate. The effectiveness of the hybrid material synthesis methodology was confirmed indirectly, using Fourier transform infrared spectroscopy, elemental and colorimetric analysis. Dispersive-morphological analysis indicates that the products with the best properties were obtained using 10 parts by weight of magnesium lignosulfonate per 100 parts of Syloid®244 silica. The relatively high thermal stability recorded for the majority of the synthesized products indicates the potential use of this kind of a material as a polymer filler. Results indicating the high electrokinetic stability of the materials are also of great importance. Additionally, the very good porous structure properties indicate the potential use of silica/lignosulfonate systems as biosorbents of hazardous metal ions and harmful organic compounds.
3
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Lignosulfonate and silica as precursors of advanced composites

100%
Klapiszewski Ł., Nowacka M., Siwińska-Stefańska K., Jesionowski T.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 3
103-109
EN
Advanced silica/lignosulfonate composites were obtained using magnesium lignosulfonate and silica precipitated in a polar medium. For comparative purposes analogous synthesis was performed using commercial silica Aerosil®200. Lignosulfonates are waste products of paper industry and their application in new multifunctional materials is of great economic interest. The composites obtained were subjected to thorough characterization by determination of their physicochemical, dispersive-morphological and electrokinetic properties. Their particle size distribution was measured, SEM images were taken, FT-IR analysis and colorimetric study were made, thermal and electrokinetic stabilities and parameters of porous structure were also determined. The results can be of interest in further application studies
4
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A silica-silver nanocomposite obtained by sol-gel method in the presence of silver nanoparticles

100%
Racles C., Nistor A., Cazacu M.
Open Chemistry
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2013
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vol. 11
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issue 10
1689-1698
EN
Silver nanoparticles (AgNPs) were obtained by a redox reaction, using a glucose-containing cyclosiloxane as a reduction agent and stabilizer. Then the AgNPs aqueous solution was used as the reaction medium for the sol-gel process, starting from tetraethylorthosilicate (TEOS) as silica precursor. The nanocomposite material resulted (SilAg) after solvent removal, aging and calcination and was investigated by infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-ray system (SEM/EDX), transmission electron microscopy (TEM), energy-dispersive X-ray fluorescence spectroscopy (EDXRF), X-ray diffraction (XRD) and dynamic vapor sorption (DVS). The results were compared to model silicas obtained without silver. A higher condensation degree in SilAg was obtained due to the basic medium used in the first step and was confirmed by a sorption capacity lower than for the model silicas. The solid surface area calculated with GAB analysis using DVS data for the water vapors is 210 m2 g−1. The nanocomposite showed good catalytic activity for hydrogen peroxide decomposition. [...]
5
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Copper removal by carbon nanomaterials bearing cyclam-functionalized silica

100%
Kurczewska J., Schroeder G., Narkiewicz U.
Open Chemistry
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2010
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vol. 8
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issue 2
341-346
EN
The synthesis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials coated with cyclam-bonded silica has been described. The organic layer was identified by Fourier transform infrared spectroscopy and elemental analysis. The functionalized magnetic nanomaterials were employed to extract the divalent cations: copper, calcium, cobalt, manganese and nickel from aqueous solutions. Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by inductively coupled plasma mass spectrometry. Influence of different parameters viz. pH, amount of the compound studied, contact time, on the cation extraction was investigated. Under optimum conditions copper extraction was significantly more efficient when compared with other coexisting ions. [...]
6
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Temperature effects on the adsorption of polyvinyl alcohol on silica

88%
Wiśniewska M.
Open Chemistry
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2012
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vol. 10
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issue 4
1236-1244
EN
The influence of temperature on the adsorption of polyvinyl alcohol (PVA) on a silica surface was studied from 15–35°C. The structure of the polymer adsorption layer was determined from spectrophotometric, viscosity and thermogravimetric measurements. The amount of PVA adsorbed, macromolecules’ conformation in solution, thickness of the polymer adsorption layer, and changes in the heating curve of SiO2 with adsorbed polymer were determined. Temperature influences the PVA chain conformation in solution and the structure of the polymer adsorption layer. A temperature rise causes relaxation of polymer coils which results in an increase in the linear dimensions of PVA chains in the solution, the creation of a thicker adsorption layer, and an increase in polymer adsorbed. Polymer adsorption on the silica surface also causes changes in the heating curve of these systems. The mass losses due to heating are smallest for the systems obtained at 15°C because the least polymer is adsorbed at this temperature. [...]
7
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Effect of Additives on the Densification Processes and Properties of Silica-Based CMCs

88%
Ko S.-Y., Yong S.-M., Lee S. J., Cheong D.-I., Baek S.
Archives of Metallurgy and Materials
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2018
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vol. 63
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issue 3
8
Content available remote

In vitro biological activity comparison of some hydroxyapatite-based composite materials using simulated body fluid

88%
Czikó M., Bogya E.-S., Barabás R., Bizo L., Stefan R.
Open Chemistry
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2013
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vol. 11
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issue 10
1583-1598
EN
Hydroxyapatite composites are the main biomaterials used for metal implant coatings. Their in vitro study is very important. That is why their behavior was monitored in simulated body fluid (SBF), which is a solution with ion concentrations and pH value similar to those of human blood plasma. Silica, chitosan and gelatin-doped hydroxyapatite-based biomaterials were studied in SBF; the samples were characterized pre-, during and post-SBF immersion using infra-red, scanning and transmission electron spectroscopy and X-ray diffraction methods. The solubility of materials in SBF was determined, and the variation of Ca2+ and phosphorus concentration was also recorded during SBF experiments. The results were compared and their in vitro biological activity was determined. [...]
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