电子鼻检测污染土壤中挥发性氯代烃的适用性研究

开发了一套以光离子化传感器（PID）为核心的电子鼻系统,用于污染土壤中挥发性氯代烃的快速检测.用气相色谱（GC）分析评价了预处理管对苯系物等干扰物质的去除效果;用标准气体发生装置发生不同浓度的四氯乙烯和三氯乙烯气体,比较评价了电子鼻与GC检测结果的吻合程度及测试重现性.在此基础上,选取我国长三角地区三类典型水稻土进行模拟污染土壤的通风净化实验,评价了电子鼻系统用于实时监测挥发性氯代烯烃污染土壤修复进程的可行性.结果表明：①采用RAE-SEP卤代烃分离管进行预处理,甲苯、乙苯等苯系干扰物的去除率可达80%～97%,而四氯乙烯和三氯乙烯等挥发性氯代烃的选择性透过率高于90%;②电子鼻对不同浓度四氯乙烯和三氯乙烯气体的定量检测结果与GC结果相近,线性拟合斜率为1.012,相关系数R2〉0.99;③电子鼻对三类典型土壤通气脱附过程中污染物浓度的变化趋势的实时监测结果与GC检测结果基本一致,判定系数R2〉0.99（n=47）.因此,该电子鼻系统有望用于挥发性氯代烯烃污染土壤的快速检测,提高污染场地的风险评估和修复效率.

Applicability of an Electronic Nose for Detection of Volatile Chlorinated Hydrocarbons in Soil

An electronic nose principally composed of a photo ionization detector (PID) was developed for rapid detection of volatile chlorinated hydrocarbons (VCHs) in contaminated soil. Removal of interference gas such as benzene homologues with a pre-filtration tube was analyzed with gas chromatography (GC). A standard gas generator was applied to generate different concentrations of perchloroethylene (PCE) and trichloroethylene (TCE) gas, with which the determine precision and reproducibility of the electronic nose were evaluated by comparison with GC. Finally, simulated contamination soil with three typical paddy soils in Yangtze river delta region were used for ventilation purification experiments, the change of VCHs concentrations in the ventilation gas was monitored, based on which the applicability of the electronic nose was evaluated for on-line detection of the on-going of the ventilation purification process. Results showed that a halogenated hydrocarbon RAE-SEP tube was effective to remove interference gas, with 80%-97% of benzene homologues such as benzene and ethyl benzene being removed while more than 90% of VCHs passed through. With PCE or TCE gas, a linear dependence was derived between the data determined with the electronic nose and GC, the linear slope being 1.012 and R²>0.99. The electronic nose showed data consistent with GC (R²>0.99, n=47)when applied for monitoring the remediation progress in a soil ventilation process. The electronic nose is therefore possibly applicable for rapid determination of soil pollution by VCHs, improving the efficiency of pollution diagnosis and remediation.