低成本高分辨电化学传感技术探测大气NO2的研究

Low cost and high resolution electrochemical sensing for atmospheric NO_2 measurement

为有序疏解大气NO_2监测环境日益复杂及成本高昂的光学探测仪器缺乏灵活性的困扰,研制了基于低成本电化学传感技术的测量系统,以四电极电化学传感器为NO_2浓度传感载体,基于差分算法补偿痕量浓度下零点电流漂移的干扰,实现了对大气NO_2的定量.结果表明,系统在摆脱有线数传束缚的基础上可稳定探测NO_2,对100 ppbv的NO_2标气响应时间T90<34 s,标定探得其灵敏度为0.242 m V·ppbv-1,时间分辨率为10 s时探测限为1.5 ppbv(3σ).为验证准确性,将系统置于合肥西北郊科学岛进行了连续2个昼夜的大气NO_2测量,并与参考设备CRDS系统对比,探讨了测量结果,发现除去该系统因环境湿度贴近极限工作湿度时测量结果奇异部分,二者表现出良好的一致性,R2达到0.940,线性拟合斜率为1.047±0.006,接着分析了温湿度和其他痕量气体等干扰源.研究表明,本技术可为大气NO_2高分辨在线监测提供一种低成本便携途径.

In order to face the more and more complicated environment of atmospheric NO2 measurement and make up the flexibility lack of the expensive optical instruments,low-cost electrochemical sensing technology for the quantification of NO2 concentration was developed. In this method,a fourelectrode electrochemical sensor was applied for NO2 concentration detection and the interference of zero current drift was compensated by differential algorithm for trace concentration monitoring. Experimental results show that the NO2 can be stably measured and data is transmitted by wireless technique,the response time（ T90） to 100 ppbv NO2 is less than 34 s,the sensitivity of the system is 0.242 m V·ppbv^-1 and the detection limit is 1.5 ppbv（ 3σ） for NO2 at a time resolution of 10 s. To verify the accuracy of the instrument,a field experiment was carried out in the northwestern suburb of Hefei city,the Hefei Science Island,for 2 consecutive days of atmospheric NO2 measurements,and compared simultaneously with a CRDS instrument. Their comparison results show that the two instruments have a great agreement（ R2= 0.940） and have a fitting slope of 1.047±0.006 except for the singular data measured in an extreme humidity. Then,the interference sources,such as temperature,humidity and other trace gases,are analyzed,the results show that our electrochemical sensing technology is a low cost and portable means for the detection of atmospheric NO2 with high resolution.