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Permeation of VOC vapours through carbon nanotube network membranes controlled electrically
Slobodian, P. ; Říha, Pavel ; Olejník, R.
In this letter, we report the increase of permeation rates of some typical volatile organic compounds through entangled carbon nanotube networks by an electric current. The change in the permeation rate is reversible when the\ncurrent is turned off. The permeation rise is partly probably due to Joule effect and thus increased membrane temperature and vapor pressure in the vicinity of the inlet side of membrane. However, the effects of vapor polarity and electrostatic interaction of vapors and charged nanotubes seem to be also involved and contribute to the differentiation between alcohol and carbohydrate vapors permeation.
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Organic vapour sensing and thermoelectric properties of carbon nanotubes/ethylene-octene copolymer composites combined in a thermopile
Slobodian, P. ; Říha, Pavel ; Olejník, R. ; Benlikaya, R.
A novel self-powered thermoelectric vapor sensor, whose thermogenerated voltage was modulated by chemical vapors is presented. The sensor was made of composites of oxidized multi-walled carbon nanotubes within\nethylene-octene copolymer. The multi-walled carbon nanotubes within ethylene-octene copolymer showed that the oxidation with KMnO4 enhanced its p-type electrical conductivity and that the thermoelectric power increase was proportional to the formation of new oxygen-containing\nfunctional groups on the surface of carbon nanotubes. When this composite was subjected to a saturated vapor of either heptane (aliphatic hydrocarbon), toluene (aromatic hydrocarbon) or ethanol (alcohol), its respective relative resistance increased in average by 3.6, 1.1 and 0.05.
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Gas and Vapour Transport and Mechanical Properties of Carbon Nanotube and Carbon Fibre-Reinforcement of Ethylene-Octene Copolymer Membranes
Sedláková, Zuzana ; Clarizia, G. ; Bernardo, P. ; Jansen, J.C. ; Slobodian, P. ; Svoboda, P. ; Kárászová, Magda ; Friess, K. ; Izák, Pavel
Helium, hydrogen, nitrogen, oxygen, methane and carbon dioxide were used for gas permeation rate measurements. Theoretical Maxwell’s model was used to predict and interpret gas transport properties in MMMs. Vapour transport properties were studied for aliphatic hydrocarbon (hexane), aromatic compound (toluene), alcohol (ethanol), as well as water. Organic vapours result more permeable than permanent gases in EOC-based membranes, with toluene and hexane permeabilities being about two orders of magnitude higher than permanent gas permeability. Carbon-filled membranes show that the EOC is an organophilic material that offers perspectives for application in gas/vapour separation with improved mechanical resistance.
Plný tet: SKMBT_C22014090110400 -  PDF
Plný text: content.csg - PDF
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Multi-wall carbon nanotube networks prepared from pure MWCNT and their oxidised forms effect of compressive strain on electric resistence
Olejník, R. ; Slobodian, P. ; Říha, Pavel ; Kimmer, D. ; Sáha, P.
Multi-wall carbon nanotube networks were prepared by filtration of CNT aqueous dispersions. CNT dispersions were prepared with the help of surfactant system (sodium dodecyl sulfate with amylalcohol) by ultrasonication. Three types of MWCNT tubes were used. The first were pure CNT delivered by supplier. The others were oxidized CNT oxidized (1. acid solution of KMnO4; 2. the mixture of acids H2SO4 + HNO3). It was found that oxidization significantly changes properties of prepared carbon nanotube networks. There were observed differences in porous structures networks analyzed by SEM microscopy. Moreover, the apparent density of prepared MWCNT networks also changes according to the used CNT. The network electrical resistance is also affected by process of MWCNT oxidation as well as by compressive strain. It was found that the network resistance is sensitive to compressive strain both in the course of strain growth and when loading/unloading cycles are imposed.
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Application of Nanofibres in Filtration Processes
Kimmer, D. ; Vincent, I. ; Petras, D. ; Fenyk, J. ; Zatloukal, M. ; Sambaer, W. ; Slobodian, P. ; Salmela, H. ; Lehtimaki, M. ; Ždímal, Vladimír
The metod making possible to achieve the requireed of the nanofibres is demonstrated on the influence of telative humidity and solvent type on the fibre- forming process taking place in an electrostatic field. the effect of homogenity of the nanofibre deposition on the collection substrate is assessed empoying images from scanning electron microscopy (SEM) and tests of filtering abilities oh the nanofibre layers. Also, some measurements obtained when nanofibres were used in filtation of air, liquids and dispersions of carbon nanotubes in a liquid are presented.
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