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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
2011-2-17
pubmed:abstractText
The influence of moisture content and temperature on the dielectric permittivity (complex resistance) of the zeolite NaY was investigated for a fixed radio frequency (RF) of 13.56 MHz. Sealed glass tubes containing zeolite with defined moisture contents were simultaneously heated in a homogeneous high-frequency electromagnetic field. The dielectric loss factor, i.e. the imaginary part of the permittivity ?(r)?, was calculated from the obtained heating rates. On the basis of the resulting values for various moisture contents and temperatures and utilizing the knowledge of elementary cation hopping processes occurring at low and high frequencies (LF and HF) from the literature, a new model was introduced for the description of dielectric radio-frequency heating of moist zeolites. Since adsorption of water is correlated with an enhancement of the activation energy of the cations on SII sites, cations in the zeolite NaY are moving from SII sites to unoccupied SIII sites when the water content is increasing. Thus, four different transfer processes for the cations have to be considered in total. On the basis of these assumptions, the resulting dielectric loss factor ?(r)? as a function of water content and temperature for a fixed frequency of 13.56 MHz was modelled. The experimental data are in good agreement with the values obtained from the model. Especially, the measured pronounced maximum of dielectric loss at temperatures below 300 °C and water contents below 4 wt.-% can be explained by the new model.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Mar
pubmed:issn
1463-9084
pubmed:author
pubmed:issnType
Electronic
pubmed:day
7
pubmed:volume
13
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4119-25
pubmed:year
2011
pubmed:articleTitle
Influence of moisture content and temperature on the dielectric permittivity of zeolite NaY.
pubmed:affiliation
Helmholtz Centre for Environmental Research-UFZ, Department of Environmental Engineering, Permoserstr. 15, 04318 Leipzig, Germany.
pubmed:publicationType
Journal Article