| In recent years, indoor air pollution has caused great concern around the world. The pollution of formaldehyde and xylene caused by the interior decoration, and the occupational exposure to n-hexane and trichloroethylene increasingly serious in our country. The World Health Organization has listed indoor air pollution as one of the 10 major threat to human health. Therefore, it’s necessary to develop toxic gas sensors with advantages of simplicity, rapid response, high sensitivity, good stability, as well as ensuring the safety monitoring of indoor air quantity.CTL-based gas sensor has become a hot research for it’s characteristics of rapid response, simple operation, non-solvent, easy miniaturization and satisfactory durability. In this paper, the author proposed a novel and high sensitive gas sensing mode based on thermal desorption/cataluminescence（TD/CTL）.The conclusions of this study were:（1） In Chapter 2, a novel and highly sensitive sensor for gaseous n-hexane utilizing the sensing material of Y2O3-Al2O3 （mass ratio of 2:1） was developed based on TD/CTL. Under the adsorbent of Tenax-TA, catalytic temperature of 200℃, wavelength of 400 nm, the linear range was 1.32?132.00 mg/m3 with a detection limit （3σ） of 0.40 mg/m3. The sensitivity of this TD/CTL n-hexane sensor increased by 20 times than CTL-based n-hexane sensor without adding thermal desorption apparatus under the same experiment conditions. This proposed TD/CTL-based n-hexane sensor showed a high sensitivity and allowed safety monitoring of n-hexane in workplace.（2） In Chapter 3, a formaldehyde gas sensor based on TD/CTL using TiO2-Y2O3 （mass ratio of 1:3） as a probe was proposed. Quantitative analysis was performed at an optimal adsorbent of actived carbon, catalytic temperature of 195 oC, wavelength of 490 nm. The linear range of CTL intensity versus concentration of formaldehyde was 0.026-1.30 mg/m3 with the detection limit （3σ） of 0.010 mg/m3. In order to evaluate the validity of this proposed formaldehyde sensor, classic UV spectrometry was performed for comparision. The results agreed well with that obtained by UV spectrometry. This proposed TD/CTL-based formaldehyde sensor offered a high sensitivity and allowed safety monitoring of trace formaldehyde in indoor air.（3） In Chapter 4, a highly selective and sensitive trichloroethylene （TCE） sensor based on TD/CTL using nanocomposites ZnO-Y2O3 （mass ratio of 2:1） was proposed. Under the adsorbent of Tenax-GR, catalytic temperature of 210℃, wavelength of 440 nm, the linear range of CTL intensity versus concentration of TCE was 14.65-586.00 mg/m3 with the detection limit （3σ） of 13.34 mg/m3. An important advantage of this proposed TCE sensor was its high selectivity to TCE. This proposed TD/CTL-based TCE sensor showed a high selectivity and high sensitivity and allowed safety monitoring of trace TCE in workplace.（4） In Chapter 5, a model of a sensor array system, which consists of three cataluminescence sensors based on nanosized Y2O3, ZrO2,γ- Al2O3 as catalysts, for discrimination and quantitative analysis of three xylene isomers. Discrimination of three isomers, namely o-xylene, m-xylene and p-xylene according to their chracteri- stic CTL spectra. Three linear regression equations of the cataluminescence intensity vs. the gas concentrations in the range of 86.70-8670.00 mg/m3 were established from the sensor array system. The least squares method was employed for solving the simultaneous equations and quantifying the concentrations of the three isomers. The concentrations of two artificial samples containing the tertiary mixture were analysed with satisfactory results. |
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