Design and implementation of a preconcentrator with Zeolite NaY for sensitivity enhancement of commercial gas sensors at low NO2 concentrations

Abstract

Zeolite NaY was used to implement a NO2 preconcentrating system for the first time which provided the detection of ppb concentration levels of NO2 with high response level. NO2 gas is among air pollutants that significantly affect the quality of human health, even at low concentrations, which necessitates commercial NO2 sensors to attain low detection capability. In this work, we have reported responses of a commercial NO2 sensor to low concentration levels of NO2. Responses were improved by ∼44 times through using a designed and fabricated preconcentration system. The preconcentrator was composed of different sections in which the most important part was zeolite NaY as a NO2 adsorbent: it adsorbed NO2 molecules from the air polluted with 300 ppb NO2 during the adsorption cycle, then by applying a heating pulse, it was forced to release preadsorbed NO2 species into a smaller chamber in which a commercial gas sensor was placed to monitor the variations of NO2. In this process, the sensor response increased noticeably. System features such as durability and cross sensitivity, and preconcentrator working conditions, such as desorption temperature, duration of adsorption time, heating rate, and the air circulation flow were investigated. Results were described and it is shown that NO2 detection at ppb levels with high sensitivity is possible with such a low price preconcentration system.