电子鼻预处理装置的开发及适用性研究

针对气敏传感器的信号响应受气体湿度影响较大的问题,开发了一套用于快速检测和实时监测土壤中挥发性氯代烃污染的电子鼻的预处理装置.优选了干燥剂的材质,评价了最适干燥剂的除湿性能和对氯代烃化合物的吸附情况;把预处理装置与电子鼻联用,通过与气相色谱（GC）检测结果的比较,评价了其用于土壤通风净化过程监测的适用情况.结果表明：①以无水氯化钙和卤代烃分离管搭配组合的干燥装置效果最佳,湿度去除率达99%以上,电子鼻各传感器的基线值与对照组接近;②上述干燥剂连续通入湿度为75%的空气,90 min内湿度几乎可完全去除,120 min内湿度去除率保持在95%以上,对传感器的基线影响较小.③预处理装置未造成检测气体的吸附损耗,通入干燥预处理装置前后的挥发性氯代烃气体浓度差异只有3%～5%;④在土壤通风脱附过程的检测中,通气湿度98%以上的情况下,预处理装置在120 min内对湿度去除率达99%以上;电子鼻与GC对四氯乙烯污染物的检测结果线性拟合判定系数R2〉0.99（n=18）,表明配以干燥预处理装置的电子鼻能够较好地适用于土壤修复过程监测.

Implementation of a Pretreatment Device for an Electronic Nose

A pretreament device was implemented for removing the interference of humidity on the baseline signal response of sensors in an electronic nose, which was used for rapid detection and real-time monitoring of volatile chlorinated hydrocarbons (VCHs) pollution in soil. The desiccant material was optimized, and the humidity removal performance and adsorpiton of VCHs was studied. The pretreatment device was evaluated by both the electronic nose and gas chromatography (GC) for its applicability in monitoring the PCE concentration in the desorption gas during the soil ventilation process. The following results were obtained: 1) A desiccant tube with anhydrous calcium chloride followed by a halogenated hydrocarbon separation tube was the best device, with a humidity removal rate of over 99%, and the baseline values of each sensor in the electronic nose were close to that of the control. 2) The desiccant device described above could continuously remove almost all the humidity from air with 75% humidity within 90 min, and the humidity removal rate remained above 95% within 120 min, while little interference was observed on the baseline of each sensor. 3) Little adsorption was observed by the pretreatment device, the relative error being only 3% - 5% between the concentration of VCHs before and after the filtration by the pretreatment device. 4) When applied for monitoring the remediation progress in a soil ventilation process, 99% of humidity was removed within 120 min from air with humidity of over 98%, and the data determined with the electronic nose and GC fitted each other very well, with R2 > 0.99. From the above, the pretreatment device connected with the electronic nose was considered to be applicable for monitoring the soil remediation process.