caa a22 4500 463189264 CHVBK 20180406164904.0 cr unu---uuuuu 170326e20071001xx s 000 0 eng 10.1007/s10973-007-8482-0 doi (NATIONALLICENCE)springer-10.1007/s10973-007-8482-0 Thermo-XRD investigation of monoionic montmorillonites mechanochemically treated with urea [Elektronische Daten] [Eva Abramova, I. Lapides, S. Yariv] Montmorillonite (M) saturated with H+,Li+,Na+,K+,Rb+,Cs+,NH4 +,Mg2+,Ca2+,Sr2+,Ba2+,Mn2+,Co2+,Cu2+,Al3+ and Fe3+ were dry-ground with urea (U) in mass ratios U/M between 0.1 and 2.0 in an agate mortar and diffracted by X-ray. Extensive swellings occurred with H-, Li-, Na-, di-and trivalent cation-clays, suggesting the formation of urea-montmorillonite intercalation complexes. Mechanochemically treated samples were heated at different temperatures up to 375°C. The rise in temperature was accompanied by a decrease in the basal spacing. There was a correlation between the results of the thermo-XRD-analysis and the fine structures of the urea-montmorillonite complexes described in the literature. Five stages in the basal spacing vs. temperature curves were identified. In the first stage (at 150°C) the decrease was due to dehydration. In the second stage (175°C) this dehydration was accompanied by some thermal intercalation of excess urea. The other stages (at 225, 325 and 375°C) were associated with the degradation of urea and the condensation of the degraded species to polymeric products. At 375°C Li-, Na-, K-NH4-, Mh-, Co- and Cu-montmorillonite collapsed, indicating that urea was evolved. The other urea-clay complexes did not collapse due to intercalated polymers formed by the degradation products of urea. Springer Science+Business Media, LLC., 2007 adsorption nationallicence intercalation complexes nationallicence mechanochemical adsorption nationallicence montmorillonite nationallicence thermo-XRD-analysis nationallicence urea-montmorillonite complexes nationallicence Abramova Eva Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut Lapides I. Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut Yariv S. Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 99-106 1388-6150 90:1<99 2007 90 10973 https://doi.org/10.1007/s10973-007-8482-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-007-8482-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Abramova Eva Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut NATIONALLICENCE 700 1- Lapides I. Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut NATIONALLICENCE 700 1- Yariv S. Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 99-106 1388-6150 90:1<99 2007 90 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer