Preparation, Characterization And Performance Of Ti02 Based Catalytic Pellet For Detection Of Volatile Organic Compound Under Uv Light
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Date
2009-09
Authors
Juhari, Jusliha
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Abstract
Nowadays, environmental regulations on volatile organic compounds (VOCs)
have been tightened all over the world, as their rapid evaporation and toxic or
carcinogenic nature at high concentrations in the air make them dangerous to human
beings. Accordingly, in order to detect dangerous and toxic VOCs, high performance
gas sensors / made up from IQW cost materials and simplicity in fabrication are
required to measure various kinds and quantities ofVOCs.
In the present study, a sensing material (La-modified Ti02! Sn-modified
Ti02) was developed by incorporating lanthanum (La) or tin (Sn) onto Ti02-based
material by sol-gel method in different orders with additive loadings range between
0.0 at.% and 10.0 at.% and calcination temperatures range between 500°C and 900
°C, respectively. Then, the sensing material was pressed into a catalytic pellet with a
diameter of 20 mm and a thickness of 2 mm. The sensing materials (powders and
catalytic pellets) were characterized using thermal gravimetric analysis (TGA), X-ray
diffraction (XRD) , transmission electron microscopy (TEM) , surface analysis (N2
adsorption-desorption), scanning electron microscope (SEM) and energy dispersive
X-ray (EDX) spectroscopy. The detection activity was performed in a measurement
chamber with heating facilities operated at temperatures between 50°C and 400°C.
The performance of selected catalytic pellet under various operating conditions was
further studied with different concentrations of VOC vapor (ethanol, methanol and
acetone) between 1000 ppm and 3000 ppm under the influence of UV light
irradiation.
Based on the detection performance and characterization study, the best result
was obtained when Ti02 was modified with Sn additive while the optimum loading
of Sn and calcined temperature was 2.5 at.% and 600°C, respectively. The
performance of selected catalytic pellet (2.5-Sn-Ti02-600) under various operating
conditions was at the optimum when operating temperature was at 250°C with the
highest sensitivity of ~ -38.12 for 3000 ppm of ethanol vapor detection. The
sensitivity of the catalytic pellet was greatly enhanced by the UV light irradiation to
sensitivity values of ~ 73.57, while reducing the optimum operating temperature to
200°C. The gas-sensing mechanism of the catalytic pellet was found to be a surfacecontrolled
type and the electrical resistance-temperature characteristic indicated an ntype
semiconductor.
In conclusion, the 2.5-Sn-Ti02-600 catalytic pellet was a suitable pellet
sensor for the VOC detection under UV light irradiation due to the low cost materials
used and eases of fabrication with high VOC sensitivity even at lower operating
temperature.
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Keywords
Environmental regulations on volatile organic compounds , have been tightened all over the world