The Study Of Detecting Volatile Organic Compounds By Nanometer Cataluminescence Method

Compared with the sensor of photoluminescence, chemiluminescence sensor has ahigh sensitivity and selectivity as well as a wider linear range, which does not require anexternal source and complex circuit and can avoid the light scattering. Thus, people showa keen interest on this kind of sensor. However, some shortcomings have been found inthe routine analysis of chemiluminescence sensor when applying it. For example, theshort life expectancy of the sensor and the signal drift caused by light reactantconsumption, which limit the application of chemiluminescence sensors in practicalanalysis. Therefore, it is of great importance to develop such a kind ofchemiluminescence sensor, which is featured by high sensitivity and stability, simplemanufacture and long service life in the practical application. The continuousdevelopment of nanotechnology provides new opportunities for the study ofchemiluminescence sensor. Some of the gas can produce the phenomenon of strongchemiluminescence on the surface of specific nanometer material. Therefore, thenanometer materials can be used to design different types of cataluminescence sensor.The thesis takes the nanometer catalyst as a sensitive material to design four kinds ofcataluminescence sensor, which broaden the application scope of the cataluminescencemethod. The main contents are as follows:1. The CTL system of ethyl ether-nanosized Co3O4has been studied. The effects ofwavelength, temperature, and flow rate on CTL were studied. The optimal detection tem-perature of this system is176℃that was lower than previously reported ethyl ether CTLsystem. Under the optimal conditions, the CTL intesity and concentration showed goodlinear relitionship within the range of4.0-1500ppm and response time is only2s. No oronly little interference of foreign substance for the determination of ethyl ether. Thisindicated that this system can achieve the rapidly detection of ethyl ether in the air.2. The CTL characterstics of acetone on different nanomaterials surface was studiedand an acetone sensor based on nano-MgO was constructed. The sensor has highsensitivity and good selectivity to acetone vapor at low temperature. When the same concentration of benzene, acetonitrile, n-hexane, methylbenzene, ethyl acetate,tetrachloromethane, formaldehyde, methanol, and trichloromethane were passing throughthe sensor, only trichloromethane, methanol, formaldehyde and tetrachloromethane couldcause4.8%,3.2%,2.4%,1.7%of interference respectively. The gas sensor could beworked for more than100h and CTL intensity without decrease, the ralative standarddeviation was3.50%, which indicated that the has good durability and steadyperformance.3. Studied the CTL behavior of ethyl acetate gas on nanocomposites ZnS/TiO₂andestablished a high sensitivity CTL system based on CTL priciple for detection of ethylacetate. Under the optimal conditions, the good linear relationship between the CTLintesity and concentration within the range of3.0-1200ppm, and the correlationcoefficient of0.9990, the detection limit of1.28ppm. None or only very low levels ofinterference were observed when the common volatile organic compounds were passingthrough the sensor, while only tetrachloromethane could cause6.5%of interference. Thissenser worked continuously for120h showed good steady performanceand the relativestandard deviation is less than4.8%.4. A new cataluminescence （CTL） sensor using nanosized Ag doped with CuO wasdesigned to monitor formaldehyde gas. When the mass content of CuO was about30%,formaldehyde CTL intensity achieved maximum and minimal interference. A newmethod for determination of formaldehyde was established which based on systematicstudy of experimental conditions. For this method of detection limit was1.8ppm and therelative standard deviation of CTL was2.3%, the recovery rate of97.5%-102.5%.