Water vapor absorption in porous media polluted by calcium nitrate studied by time domain nuclear magnetic resonance (Articolo in rivista)

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Label
  • Water vapor absorption in porous media polluted by calcium nitrate studied by time domain nuclear magnetic resonance (Articolo in rivista) (literal)
Anno
  • 2009-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/jp902781f (literal)
Alternative label
  • Mirko Gombia; Villiam Bortolotti; Robert J.S. Brown; Mara Camaiti; Luisa Cavallero; Paola Fantazzini (2009)
    Water vapor absorption in porous media polluted by calcium nitrate studied by time domain nuclear magnetic resonance
    in The journal of physical chemistry. B
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Mirko Gombia; Villiam Bortolotti; Robert J.S. Brown; Mara Camaiti; Luisa Cavallero; Paola Fantazzini (literal)
Pagina inizio
  • 10580 (literal)
Pagina fine
  • 10586 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#altreInformazioni
  • Prodotto digitalizzato (literal)
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  • 113 (literal)
Rivista
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  • 7 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Department of Physics - University of Bologna (Italy); Department DICMA - University of Bologna (Italy); No Affiliation- Claremont- California (USA); ICVBC-CNR (literal)
Titolo
  • Water vapor absorption in porous media polluted by calcium nitrate studied by time domain nuclear magnetic resonance (literal)
Abstract
  • Nuclear magnetic resonance relaxation analysis of liquid water 1H nuclei in real porous media, selected for their similar composition (carbonate rocks) and different pore space architecture, polluted with calcium nitrate, is presented to study the kinetics of water condensation and salt deliquescence inside the pore space. These phenomena are responsible for deterioration of porous materials when exposed to environmental injury by pollution in a humid atmosphere. The theory is well described for simple pore geometries, but it is not yet well understood in real porous media with wide distributions of pore sizes and connections. The experiment is performed by following in time the formation of liquid water inside the pore space by T1 and T2 relaxation time distributions. The distributions allow one to see the effects of both the salt concentration and the pore space structure on the amount of water vapor condensed and its kinetics. It is shown that, for a given lithotype, even with different amounts of pollutant, the rate-average relaxation time T1ra tends to increase monotonically with NMR signal, proportional to the amount of liquid water. T1ra is often inversely associated with surface-to-volume ratio. This suggests a trend toward the filling of larger pores as amounts of liquid water increase, but it does not indicate a strict sequential filling of pores in order of size and starting with the smallest; in fact, relaxation time distributions show clearly that this is not the case. Increased amounts of salt lead to both markedly increased rates and markedly increased amounts of water absorption. NMR measurements of amounts of water, together with relaxation time distributions, give the possibility of information on the effect of pollution in porous materials exposed to humid atmospheres but sheltered from liquid water, even before the absorption of large amounts of moisture and subsequent damage. These phenomena are of importance also in other fields, such as the exploitation of geothermal energy. (literal)
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