10.5.4 Volatile Organic Compounds
The risk of explosion is the primary adverse effect for exposure of hydrogen and
hydrocarbon especially methane above the threshold limit value concentration as 4%
in atmosphere having high level of oxygen. Moreover, hydrocarbon gas like methane is a much more powerful greenhouse gas even than that of carbon dioxide. The
hydrocarbon gases originated from sources such as landfills, fossil fuel production
sites, petrochemical industry, and agricultural areas. The important materials used
for the sensing of three main types of volatile organic compounds such as alcohol,
chlorinated hydrocarbon, and acetone are shown in Table 10.2.
As shown in Fig. 10.22, the tin dioxide nanocomposite doped with 5.0 weight
percentage of samarium oxide was reported to have selective sensing for ethanol
over carbon monoxide at 300
C operating temperature (Habibzadeh et al. 2010).
The cross sensitivity in presence of other volatile organic compound gases was
reported using CNT films to 500 ppm ethanol at 165
C under dry nitrogen and 80%
relative humidity (Cantalini et al. 2003). Similarly, CNT sensors using two transducer mechanisms, resonant frequency and reflectivity changes, reported for the
detection of various organic vapors such as methanol, ethanol, isopropyl alcohol,
acetone, ethyl acetate, toluene, etc. (Penza et al. 2004a; Penza et al. 2005a, b, c). It
was found that indium oxide nanowires exhibited high response, good selectivity,
and very short response time to dilute ethanol (Xiangfeng et al. 2004). The layer of
thermally treated tin dioxide nanoparticles exhibited good sensitivity with detection
limit as low as 1.7 ppm to alcohol vapors like methanol, ethanol, and propanol (Chiu
and Yeh, 2007).
A surface aquatic wave sensor fabricated by spray casting CNT solutions with
silicon dioxide coating onto quartz substrates was developed to measure ethanol at
room temperature with detection limit of 3.9 ppm (Penza et al. 2004b, 2007). The
sensitivity to ethanol vapors was described by using tin dioxide-coated CNT devices
(Liang et al. 2004), tin dioxide nanocomposite films with CNT (Wisitsoraat et al.
2006), tin dioxide-decorated MWNTs (Liu et al. 2006), and CNT–tin dioxide core–
shell nanostructures at 300
C operating temperature (Chen et al. 2006). The
selective sensing of ethanol and methanol vapors over the other volatile organic
compounds such as hexane, tetrahydrofuran, cyclohexane, acetone, chloroform,
ethyl acetate, methanol, toluene, N,N-dimethyl formamide, and carbon tetrachloride
was reported by changing the composition of the aligned CNT–poly(vinyl acetate)
nanocomposite (Wei et al. 2006). The nanocomposite of poly(3-methylthiophene)functionalized CNT showed selectivity to different chloromethane vapors over the
other volatile organic compounds like methane, acetone, acetaldehyde, benzaldehyde, tetrahydrofuran, methanol, or ethanol (Santhanam et al. 2005). The nickel
oxide-decorated zinc oxide nanowires were proved to provide a promising material
platform for the highly sensitive and selective detection of methanol and formaldehyde with a ppb level (Na et al. 2012). As shown in Fig. 10.23, a significantly high
selectivity to ethanol vapor was observed by cataluminescence emission from
catalytic oxidation of ethanol on the surface of zinc oxide nanoparticles over the
378
P. Kar
The risk of explosion is the primary adverse effect for exposure of hydrogen and
hydrocarbon especially methane above the threshold limit value concentration as 4%
in atmosphere having high level of oxygen. Moreover, hydrocarbon gas like methane is a much more powerful greenhouse gas even than that of carbon dioxide. The
hydrocarbon gases originated from sources such as landfills, fossil fuel production
sites, petrochemical industry, and agricultural areas. The important materials used
for the sensing of three main types of volatile organic compounds such as alcohol,
chlorinated hydrocarbon, and acetone are shown in Table 10.2.
As shown in Fig. 10.22, the tin dioxide nanocomposite doped with 5.0 weight
percentage of samarium oxide was reported to have selective sensing for ethanol
over carbon monoxide at 300
C operating temperature (Habibzadeh et al. 2010).
The cross sensitivity in presence of other volatile organic compound gases was
reported using CNT films to 500 ppm ethanol at 165
C under dry nitrogen and 80%
relative humidity (Cantalini et al. 2003). Similarly, CNT sensors using two transducer mechanisms, resonant frequency and reflectivity changes, reported for the
detection of various organic vapors such as methanol, ethanol, isopropyl alcohol,
acetone, ethyl acetate, toluene, etc. (Penza et al. 2004a; Penza et al. 2005a, b, c). It
was found that indium oxide nanowires exhibited high response, good selectivity,
and very short response time to dilute ethanol (Xiangfeng et al. 2004). The layer of
thermally treated tin dioxide nanoparticles exhibited good sensitivity with detection
limit as low as 1.7 ppm to alcohol vapors like methanol, ethanol, and propanol (Chiu
and Yeh, 2007).
A surface aquatic wave sensor fabricated by spray casting CNT solutions with
silicon dioxide coating onto quartz substrates was developed to measure ethanol at
room temperature with detection limit of 3.9 ppm (Penza et al. 2004b, 2007). The
sensitivity to ethanol vapors was described by using tin dioxide-coated CNT devices
(Liang et al. 2004), tin dioxide nanocomposite films with CNT (Wisitsoraat et al.
2006), tin dioxide-decorated MWNTs (Liu et al. 2006), and CNT–tin dioxide core–
shell nanostructures at 300
C operating temperature (Chen et al. 2006). The
selective sensing of ethanol and methanol vapors over the other volatile organic
compounds such as hexane, tetrahydrofuran, cyclohexane, acetone, chloroform,
ethyl acetate, methanol, toluene, N,N-dimethyl formamide, and carbon tetrachloride
was reported by changing the composition of the aligned CNT–poly(vinyl acetate)
nanocomposite (Wei et al. 2006). The nanocomposite of poly(3-methylthiophene)functionalized CNT showed selectivity to different chloromethane vapors over the
other volatile organic compounds like methane, acetone, acetaldehyde, benzaldehyde, tetrahydrofuran, methanol, or ethanol (Santhanam et al. 2005). The nickel
oxide-decorated zinc oxide nanowires were proved to provide a promising material
platform for the highly sensitive and selective detection of methanol and formaldehyde with a ppb level (Na et al. 2012). As shown in Fig. 10.23, a significantly high
selectivity to ethanol vapor was observed by cataluminescence emission from
catalytic oxidation of ethanol on the surface of zinc oxide nanoparticles over the
378
P. Kar