| Recently years, there are many reports of odorous gases pollution. The incorrect operation of refuse landfill and sewage treatment plants and others, which makes atmosphere full of stimulant gases, and surrounding people complaint a lot. Malodorous is mainly defined as some gases which have stimulant smell and can bring unhappy reaction for people. There are about 4000 kinds of malodorous gases. However, most of the research is about the gases of sulfur-containing compounds and styrene. The relevant detection methods are sensory and instrument. Detection system of gas chromatography equipped with FPD or MS has high sensitivity, is mainly used to separate and detect volatile compounds. Nevertheless, these equipments have the characteristics of large volume, high power consumption and difficult to carry, which brings inconvenience to scene detection. Surface acoustic wave(SAW) sensors have properties of rapid response and high sensitivity, also easy to carry. The technology, combine SAW sensors with pattern recognition, is popular in domestic and overseas researchers and is apply to detection of nerve agents, explosive gases and so on.On the basis of the electronic nose experience from domestic and foreign scholars, we use chromatographic column separation technology instead of pattern recognition to distinct mixture gases. Finally, GC-SAW system is used to detect mixture sample of sulfur-containing odorous gas components like methyl mercaptan(MM), dimethylsulfide(DMS), ethanethiol, carbon disulfide(CS2), and dimethyldisulfide(DMDS). The main contents include:(1) Choosing proper capillary column and applying gas chromatography-flame photometric detector(GC-FPD) system to detect the mixture components of five sulfur compounds and explore for optimum testing conditions. In this article, the three capillary columns(Rt-Silica BOND PLOT, TM-PLOT U and OV-1) were used to analyze mixture. The effects of GC parameters(column injecting pressure and temperature ascending modes) on separating effects were studied. The results indicated that Rt-Silica BOND PLOT column and OV-1 column were all superior: five mixture components could be separated completely within 8min, a resolution of most adjacent components is 2.525. Therefore, Silica column was applied to GC-SAW system.(2) On the basis of Louis acid-base theory, choosing HBA polymers HC as the sensitive materials of SAW sensor. The sensitivities of HC-SAW sensors on sulfurcontaining odorous gases were researched by SAW test platforms. It indicated that the HC-SAW sensor had better responses. For the five sulfur compounds, while the gas concentration is under 10,4,3,1 and 3 mg/m3 separately, the response value of sensor is proportional to the gas concentration. Gas flow is 0.5L/min, MM had no response and responses of 3.89 k Hz, 15.07 k Hz, 8.5 k Hz and 16.6k Hz were recorded when the sensor tested to the five gases at a concentration of 1mg/m3.(3) On the study of gas chromatography and SAW sensor, a system based on GCSAW technology was used to analyzed a mixture sample of five gases components. Firstly, we verified that the SAW sensor could replace FPD as a detector and can be combined with GC to detect the mixture compounds by direct injection mode. Then, based on the two conversion mode of six-way valve, the trap, gas output device capillary chromatography column and SAW sensor is be connected to concentrate and detect low concentration gases. The concentrations of five components we can detect are 0.2mg/m3 or 0.5mg/m3. |
PDF Full Text Request