Abstract: Low temperature exothermic peaks (LTEP) were previously observed in the DSC experiments on cooling of homoionic clays (Kozlowski, 2011). According to a straightforward hypothesis these thermal events might be attributed to the crystallization of the adsorbed "unfreezable" water. In the present paper, results of additional experiments by use of Modulated Differential Scanning Calorimetry (MDSC) are presented. Decomposition of the total heat capacity measured on cooling into the reversible and nonreversible components indicates that the LTEP are most likely a manifestation of freezing or a similar transition, yet quantitative determination of this freezable fraction would require realistic data on the specific heat of the adsorbed water as a function of its relative content and temperature. Detailed analysis of the apparent specific heat of soil water as a function of temperature shows that a model, in which the amount of water approximately equal to the hygroscopic water content w 0.95 (equivalent to 2-3 pseudo-layers) remains unfrozen to -70°C, proves consistent with the obtained results and referenced data on the specific heat of the adsorbed water. The hypothesis that the LTEP are related to the freezing of the water hydrating exchangeable cations seems the most reasonable in view of the obtained results and some recent data from references.
B I B L I O G R A F I A1. Agarwal, N.& Farris, R.J., "Thermal characterization of acrylic-based latex blend films by modulated and pulsed differential scanning calorimetry", Thermochimica Acta, vol. 334, 1999, p.39-47
2. Anderson, D.M.& Tice, A.R., "Low temperature phases of interfacial water in clay-water systems", Proceedings of the Soil Science Society of America, vol. 35, 1971, p.47-54
3. Anderson, D.M.& Push, R.& Penner, E., "Physical and thermal properties of frozen ground", Geotechnical Engineering for Cold Regions, 1978, p.37-102
4. Angell, C.A., "Insights into phases of liquid water from study of its unusual glass-forming properties", Science, vol. 319, 582, 2008, p.582-587
5. Angell, C.A.& Shuppert, J.& Tucker, J.C., "Anomalous properties of supercooled water. Heat capacity, expansivity, and proton magnetic resonance chemical shift from 0 to -38%", Journal of Physical Chemistry, vol. 77, 26, 1973, p.3092-3099
6. Barnes, G.T., "Phase transitions in water sorbed on silica gel", Zeitschrift für Angewandte Mathematik und Physik (ZAMP), vol. 13, 1962, p.533-544
7. Barshad, I., "Adsorption and swelling properties of clay-water systems", Bull. Calif. Dept. Nat. Res. Div. Mines., vol. 169, 1955, 90-77
8. Bogdan, A.& Kulmala, M., "DSC study of the freezing and thawing behavior of pure water and binary H2O/HNO3 and H2O/HCl systems adsorbed by pyrogenic silica: implications for the atmosphere", Journal of Aerosol Science, vol. 28, Suppl. 1, 1997, p.S507-S508
9. Brun, M.& Lallemand, A.& Quinson, J.-F.& Eyraud, Ch., "A new method for the simultaneous determination of the size and the shape of pores: thermoporometry", Thermochimica Acta, vol. 21, 1977, p.59-88
10. Bruni, F.& Mancinelli, R.& Ricci, M.A., "Multiple relaxation processes versus the fragile-to-strong transition in confined water", Physical Chemistry Chemical Physics, vol. 13, 44, 2011, p.19773-19779
11. Chaudhary, D.S.& Prasad, R.& Gupta, R.K.& Bhattacharya, S.N., "Clay intercalation and influence on crystalinity of EVA-based clay nanocomposites", Thermochimica Acta, vol. 433, 2005, p.187-195
12. Dickinson, H.C.& Osborne, N.S., "Specific heat and heat of fusion of ice", Bulletin of the Bureau of Standards, vol. 12, 1915, p.49-81
13. Diedrichs, A.& Gmehling, J., "Measurement of heat capacities of ionic liquids by differential scanning calorimetry", Fluid Phase Equilibria, vol. 244, 2006, p.68-77
14. Dorsey, N.E., "Properties of Ordinary Water Substance", 1940
15. Fabbri, A.& Fen-Chong, T.& Coussy, O., "Dielectric capacity, liquid water content, and pore structure of thawing-freezing materials", Cold Regions Science and Technology, vol. 44, 2006, p.52-66
16. Gmelin, E., "Classical temperature-modulated calorimetry: a review", Thermochimica Acta, vol. 304, 305, 1997, p.1-26
17. Gun&apos
ko, V.M.& Turov, V.V.& Turov, A.V.& Zarko, V.I.& Gerda, V.I.& Yanishpolskii, V.V.& Berezovska, I.S.& Tertykh, V.A., "Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas", Central European Journal of Chemistry, vol. 5, 2007, p.420-454
18. Gun&apos
ko, V.M.& Turov, V.V.& Zarko, V.I.& Goncharuk, E.V.& Turov, A.A., "Regularities in the behaviour of water confined in adsorbents and bioobjects studied by 1H NMR spectroscopy and TSDC methods at low temperatures", Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 336, 2009, p.147-158
19. Hatakeyama, H.& Hatakeyama, T., "Interaction between water and hydrophilic polymers", Thermochimica Acta, vol. 308, 1998, p.3-22
20. Hirasawa, Y., "Personal communication", 2011
21. Hirasawa, Y.& Urakami, W., "Study on specific heat of water adsorbed in zeolite using DSC/", International Journal of Thermophysics, vol. 31, 2010, p.2004-2009
22. Höhne, G.W.H.& Hemminger, W.F.& Flammersheim, H.-J., "Differential Scanning Calorimetry", 2003
23. Ito, K.& Moynihan, C.T.& Angell, C.A., "Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water", Nature, vol. 398, 1999, p.492-495
24. Kamasa, P.& Bokor, M.& Pyda, M.& Tompa, K., "DSC approach for the investigation of mobile water fractions in aqueous solutions of NaCl and Tris buffer", Thermochimica Acta, vol. 464, 2007, p.29-34
25. Kozlowski, T., "A comprehensive method of determining the soil unfrozen water curves
2: Stages of the phase change process in frozen soil-water system", Cold Regions Science and Technology, vol. 36, 2003, p.81-92
26. Kozlowski, T., "Low temperature exothermic effects on cooling of homoionic clays", Cold Regions Science and Technology, vol. 68, 2011, p.139-149
27. Mankin, C.J., "Mineral stability under vacuum and low temperature conditions", Nasa Institutional Research Grant (NASA-CR-125624) Project 1561-5, 1971, p.41-61
28. Robie, R.A.& Hemingway, B.S., "Heat capacities of kaolinite from 7 to 380 k and of DMSO-intercalated kaolinite from 20 to 310 K. The entropy of kaolinite Al2Si2O5(OH)4", Clays and Clay Minerals, vol. 39, 1991, p.362-368
29. Roulia, M., "Synthesis and characterization of novel chromium pillared clays", Materials Chemistry and Physics, vol. 91, 2005, p.281-288
30. Schoonheydt, R.A.& Johnston, C.T., "Surface and interface chemistry of clay minerals", Bergaya, F.& Theng, B.K.G.& Lagaly, G. (Eds.), Handbook of clay science, Developments in Clay Science, vol. Vol. 1, 2006, p.87-113
31. Stefanescu, E.A.& Schexnailder, P.J.& Dundigalla, A.& Negulescu, I.I.& Schmidt, G., "Structure and thermal properties of multilayered Laponite/PEO nanocomposite films", Polymer, vol. 47, 2006, p.7339-7348
32. Stepkowska, E.T.& Pérez-Rodríguez, J.L.& Maqueda, C.& Starnawska, E., "Variability in water sorption and in particle thickness of standard smectites", Applied Clay Science, vol. 24, 2004, p.185-199
33. Swenson, J.& Bergman, R.& Longeville, S., "Experimental support for a dynamic transition of confined water", Journal of Non-Crystalline Solids, vol. 307-310, 2002, p.573-578
34. Thomas, L.C., "Use of multiple heating rate DSC and modulated temperature DSC to detect and analyze temperature-time dependent transitions in materials", American Laboratory, vol. 33, 2001, p.26-29
35. Turov, V.V.& Leboda, R., "Application of 1H NMR spectroscopy method for determination of characteristics of thin layers of water adsorbed on the surface of dispersed and porous adsorbents", Advances in Colloid and Interface Science, vol. 79, 1999, p.173-211
36. Weiss, C.A.& Gerasimowicz, W.V., "Interaction of water with clay minerals as studied by 2H nuclear magnetic resonance spectroscopy", Geochimica et Cosmochimica Acta, vol. 60, 1996, p.265-275
37. Yao, K.J.& Song, M.& Hourston, D.J.& Luo, D.Z., "Polymer/layered clay nanocomposites: 2 polyurethane nanocomposites", Polymer, vol. 43, 2002, p.1017-1020
38. Zhao, X.-Y.& Wang, M.-Z., "Synthesis, characterization and thermal history dependence of the polymorphic structure of nylon6/montmorillonite nanocomposites", Journal of Materials Science, vol. 41, 2006, p.7225-7231 
Pełny tekst 
DOI 
Web of Science 
YADDA/CEON