[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.