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Improved selectivity, response time and recovery time by [0 1 0] highly preferred-orientation silicalite-1 layer coated on SnO2 thin film sensor for selective ethylene gas detection
(2010-01-29)
Jadsadapattarakul, Damrongsak
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Thanachayanont, Chanchana
;
Nukeaw, Jiti
;
Sooknoi, Tawan
In this work, sensing response, response time and recovery time for selective ethylene gas detection were improved by coating a layer of [0 1 0] highly preferred-orientation silicalite-1 polycrystals on SnO<inf>2</inf> thin film sensors. The sensors were prepared by primarily depositing SnO<inf>2</inf> on borosilicate glass substrates using ultrasonic spray pyrolysis technique. Conventional and [0 1 0] preferred orientations of silicalite-1 layers were then directly coated on the SnO<inf>2</inf> thin film sensors by hydrothermal crystallization technique with different gel compositions. The silicalite-1/SnO<inf>2</inf> thin film sensors were calcined at 550 °C in dry air. The crystal structure and surface morphology of SnO<inf>2</inf> and silicalite-1 layers were characterized by XRD and SEM techniques. XANES and TPR were used to verify oxidation state and reduction temperature of the SnO<inf>2</inf> thin film sensors, respectively. The interaction of C<inf>2</inf>H<inf>4</inf> and H<inf>2</inf>O with silicalite-1 was determined by TPD. The sensing performances, such as selectivity, dynamic range, response time and recovery time were evaluated for the C<inf>2</inf>H<inf>4</inf> and H<inf>2</inf>O. The results showed that the incorporated silicalite-1 layers readily improve the C<inf>2</inf>H<inf>4</inf> selectivity and dynamic range by preferential adsorption of C<inf>2</inf>H<inf>4</inf> molecules on the silicalite-1 filtering layers. The response time and recovery time for the [0 1 0] highly preferred-orientation silicalite-1/SnO<inf>2</inf> thin film sensor (t<inf>90%</inf>, 14 and 144 s) were shorter than those of the conventional one (t<inf>90%</inf>, 25 and 208 s). It is suggested that the [0 1 0] preferred-orientation silicalite-1, with a pore direction perpendicular to SnO<inf>2</inf> thin film surface, can accelerate the molecular diffusion and reduce the diffusion pathway of ethylene to the sensing film. © 2009 Elsevier B.V.
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Semi-micro preparation and characterization of mesoporous silica microspheres from rice husk sodium silicate using a non-ionic surfactant as a template: Application in normal phase HPLC columns
(2007-07-01)
Tungkananurak, Kanita
;
Kerdsiri, Sirinlux
;
Jadsadapattarakul, Damrongsak
;
Burns, Duncan Thorburn
A simple and low-cost process has been developed for the production of mesoporous silica microspheres using a non-ionic surfactant as a template in an aqueous acidic sodium silicate solution prepared from rice husk. The influences of synthesis parameters such as the sodium silicate concentration, hydrochloric acid concentration, temperature and aging time on the morphology and on particle size range are described. The product's physical and normal phase chromatographic properties are reported. © 2007 Springer-Verlag.
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Semi-micro preparation and characterization of bonded phase ODS-silica prepared from rice husk silica
(2006-04-01)
Burns, Duncan Thorburn
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Tungkananurak, Kanita
;
Jadsadapattarakul, Damrongsak
Bonded phase ODS-silica has been prepared using purified silica prepared from rice husk by burning, reflux with sodium hydroxide solution and precipitation as a gel. The gel was spray dried, further purified by washing with concentrated hydrochloric acid then distilled water prior to vacuum drying and silanization and end-capping. The product's physical and chromatographic properties are reported. © Springer-Verlag 2006.

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