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  1. Article ; Online: 2-Butanol Aqueous Solutions: A Combined Molecular Dynamics and Small/Wide-Angle X-ray Scattering Study.

    Macchiagodena, Marina / Bassu, Gavino / Vettori, Irene / Fratini, Emiliano / Procacci, Piero / Pagliai, Marco

    The journal of physical chemistry. A

    2022  Volume 126, Issue 47, Page(s) 8826–8833

    Abstract: Structural properties of 2-butanol aqueous solutions at different concentrations have been studied using small- and wide-angle X-ray scattering and molecular dynamics simulations. The experimental structure factors have been accurately reproduced by the ... ...

    Abstract Structural properties of 2-butanol aqueous solutions at different concentrations have been studied using small- and wide-angle X-ray scattering and molecular dynamics simulations. The experimental structure factors have been accurately reproduced by the simulations, allowing one to explain their variation with concentration and to achieve a detailed description of the structural and dynamic properties of the studied systems. The analysis of experimental and computational data has shown that 2-butanol, the simplest aliphatic chiral alcohol, tends to form aggregates at a concentration above 1 M, affecting also both the structural and dynamic properties of the solvent.
    MeSH term(s) Molecular Dynamics Simulation ; X-Rays ; Butanols ; Solvents
    Chemical Substances 2-butanol (0TUL3ENK62) ; Butanols ; Solvents
    Language English
    Publishing date 2022-11-17
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.2c05708
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    Rodriguez-Navarro, Carlos / Vettori, Irene / Ruiz-Agudo, Encarnacion

    Langmuir : the ACS journal of surfaces and colloids

    2016  Volume 32, Issue 20, Page(s) 5183–5194

    Abstract: Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo ... ...

    Abstract Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having important implications in the conservation of cultural heritage.
    Language English
    Publishing date 2016-05-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021/acs.langmuir.6b01065
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes

    Rodriguez-Navarro, Carlos / Vettori Irene / Ruiz-Agudo Encarnacion

    Langmuir. 2016 May 24, v. 32, no. 20

    2016  

    Abstract: Nanolimes are alcohol dispersions of Ca(OH)₂ nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)₂ particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can ... ...

    Abstract Nanolimes are alcohol dispersions of Ca(OH)₂ nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)₂ particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)₂ particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Eₐ of 29 ± 4 and 37 ± 6 kJ mol–¹ for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)₂ along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution–precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)₂ particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO₃ and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)₂ samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having important implications in the conservation of cultural heritage.
    Keywords activation energy ; air ; calcite ; calcium carbonate ; calcium hydroxide ; carbonation ; crystal structure ; cultural heritage ; dispersions ; ethanol ; isopropyl alcohol ; nanoparticles ; phase transition ; relative humidity ; transmission electron microscopy ; vaterite
    Language English
    Dates of publication 2016-0524
    Size p. 5183-5194.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021%2Facs.langmuir.6b01065
    Database NAL-Catalogue (AGRICOLA)

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    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

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