Effects of catalysts on structural and adsorptive properties of iron oxide-silica nanocomposites

Iron oxide-silica nanocomposites were prepared by sol-gel method using ammonia (NH 3 ), acetic acid (CH 3 COOH) and hydrochloric acid (HCl) catalysts to generate different pH values for the reaction conditions. As starting precursors, for the silica, respectively, for the iron oxide, tetraethylortho...

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Bibliographic Details
Published in:	The Korean journal of chemical engineering Vol. 38; no. 2; pp. 292 - 305
Main Authors:	Ianăşi, Cătălin, Ianăşi (b. Svera), Paula, Negrea, Adina, Ciopec, Mihaela, Ivankov, Oleksandr I., Kuklin, Alexander I., Almásy, László, Putz, Ana-Maria
Format:	Journal Article
Language:	English
Published:	New York Springer US 01-02-2021 Springer Nature B.V 한국화학공학회
Subjects:	Acetic acid Adsorption Adsorptivity Ammonia Aqueous solutions Biotechnology Catalysis Catalysts Chemistry Chemistry and Materials Science Crystallites Enthalpy Environmental Engineering Free energy Hydrochloric acid Industrial Chemistry/Chemical Engineering Iron oxides Materials Science Nanocomposites Silicon dioxide Sol-gel processes Surface area Surface chemistry Surface roughness Thermodynamic equilibrium 화학공학 Surfaces Nanocomposites Adsorption Magnetic Materials Catalyst
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Summary:	Iron oxide-silica nanocomposites were prepared by sol-gel method using ammonia (NH 3 ), acetic acid (CH 3 COOH) and hydrochloric acid (HCl) catalysts to generate different pH values for the reaction conditions. As starting precursors, for the silica, respectively, for the iron oxide, tetraethylorthosilicate (TEOS) and iron-III-acetylacetonate were used. The physico-chemical characterization of the materials revealed that the sample obtained with HCl catalyst displays the largest surface area (300 m 2 /g), the most compact network structure, highest surface roughness, biggest crystallite size (14 nm), magnetization (7 emu/g) and superparamagnetic behavior. These materials were tested for adsorption of Cr 6+ and Zn 2+ from aqueous solution. Sample M-HCl presented the highest surface area and was further used for adsorption of metal ions. Kinetic, thermodynamic and equilibrium adsorption measurements studies were made for Cr 6+ and Zn 2+ . To establish the material behavior from a thermodynamic point of view, temperature and contact time of adsorption process, activation energy, free energy, of standard enthalpy and entropy were calculated. The kinetic behavior was modelled by pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models and the adsorption characteristics were determined by modelling the experimental data with Langmuir, Freundlich and Sips isotherms.
ISSN:	0256-1115 1975-7220
DOI:	10.1007/s11814-020-0675-2