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Toxic gas detection using porphyrin dispersed polymer composites
The optochemical sensing performances of the porphyrin dyes dispersed in ethylcellulose (EC) matrix to toxic gases such as HCl, NO 2 and SO 2 were examined using a photo-reflection spectrum technique. The intensity of the characteristic Soret- and Q-bands of the porphyrins sensitively changed with t...
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Published in: | Sensors and actuators. B, Chemical Chemical, 2005-07, Vol.108 (1), p.393-397 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The optochemical sensing performances of the porphyrin dyes dispersed in ethylcellulose (EC) matrix to toxic gases such as HCl, NO
2 and SO
2 were examined using a photo-reflection spectrum technique. The intensity of the characteristic Soret- and Q-bands of the porphyrins sensitively changed with the concentration of the gasses. Introducing electron-donating
OCH
3 and
OH groups to the phenyl-group in the tetraphenylporphyrin (TPPH
2) molecule enhanced the sensitivity and that was in the order of TP(4-OH)
4PH
2
>
TP(3,5-OCH
3)
4PH
2
>
TPPH
2 to HCl. In contrast, electron-withdrawing
COOH group decreased in the sensitivity. It was interpreted that the electron density at the pyrrole nitrogen increased with the electron-donationing groups. Doping of dioctylphthalate (DOP) as a plasticizer to the porphyrin–EC composites remarkably modified their sensitivity and response behavior. The sensitivity to NO
2 was extremely high and sub-ppm level of detection was possible for all the composites. In the case of SO
2, the sensitivity was lower than NO
2, but the composite of TP(4-OH)
4PH
2 exhibited enough sensitivity to detect the concentration of 0.5
ppm. The sensing performance was strongly dependent on the humidity. |
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ISSN: | 0925-4005 1873-3077 |
DOI: | 10.1016/j.snb.2004.10.055 |