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Minerals 2017, 7(4), 49; https://doi.org/10.3390/min7040049

Experimental Study of Montmorillonite Structure and Transformation of Its Properties under Treatment with Inorganic Acid Solutions

1
Belov Laboratory of Mineral Cristallochemistry, Institute of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Science, Moscow 119017, Russia
2
Department of Ecological Geology, Faculty of Geology, Lomonosov Moscow State University, Moscow 119899, Russia
3
Institute of Modern Energetics and Nanotechnology Materials-IPC, Dmitry Mendeleev University of Chemical Technology of Russia, Moscow 125480, Russia
4
National Research Nuclear University, Moscow 115409, Russia
5
Laboratory of Physical Methods Application to the Study of Rock-forming Minerals, Geological Institute, Russian Academy of Sciences, Moscow 119017, Russia
6
Research Group for Heterogeneous Catalysts for Liquid-Phase Selective Oxidations, Boreskov Institute of Catalysis SB RAS, Novosibirsk 630090, Russia
*
Author to whom correspondence should be addressed.
Academic Editor: Annalisa Martucci
Received: 17 December 2016 / Revised: 2 March 2017 / Accepted: 19 March 2017 / Published: 23 March 2017
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Abstract

This paper discusses the mechanism of montmorillonite structural alteration and modification of bentonites’ properties (based on samples from clay deposits Taganskoye, Kazakhstan and Mukhortala, Buriatia) under thermochemical treatment (treatment with inorganic acid solutions at different temperatures, concentrations and reaction times). Treatment conditions were chosen according to those accepted in chemical industry for obtaining acid modified clays as catalysts or sorbents. Also, more intense treatment was carried out to simulate possible influence at the liquid radioactive site repositories. A series of methods was used: XRD, FTIR, ICP-AES, TEM, nitrogen adsorption, and particle size analysis. It allowed revealing certain processes: transformation of montmorillonite structure which appears in the leaching of interlayer and octahedral cations and protonation of the interlayer and –OH groups at octahedral sheets. In turn, changes in the structure of the 2:1 layer of montmorillonite and its interlayer result in significant alterations in the properties: reduction of cation exchange capacity and an increase of specific surface area. Acid treatment also leads to a redistribution of particle sizes and changes the pore system. The results of the work showed that bentonite clays retain a significant portion of their adsorption properties even after a prolonged and intense thermochemical treatment (1 M HNO3, 60 °C, 108 h). View Full-Text
Keywords: engineered barriers; bentonite clays; thermochemical treatments; montmorillonite; structural modification; adsorption properties engineered barriers; bentonite clays; thermochemical treatments; montmorillonite; structural modification; adsorption properties
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Krupskaya, V.V.; Zakusin, S.V.; Tyupina, E.A.; Dorzhieva, O.V.; Zhukhlistov, A.P.; Belousov, P.E.; Timofeeva, M.N. Experimental Study of Montmorillonite Structure and Transformation of Its Properties under Treatment with Inorganic Acid Solutions. Minerals 2017, 7, 49.

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