大氣PM2.5水溶性無機微粒與前趨氣體之監測技術

Abstract

本國環保署正積極地規劃PM2.5 的空氣品質管制策略，預計數年內會訂定PM2.5 的空氣 品質標準，因此大氣氣膠及其前趨氣體的即時監測十分重要，可提供有用的數據以助於 PM2.5 污染源的了解及有效控制策略的制定。目前巿售的氣體-微粒自動監測儀器的價格 十分昂貴，每台約在500~600 萬元之間，且美國環保署的評估報告認為這些自動監測儀 器的準確度仍有待確認，因此有進一步研究開發的必要。本研究團隊曾利用噴砂處理及 塗敷奈米TiO2 微粒的平行平板製成超親水的表面，成功的開發了一個平行平板的濕式 分離器(PPWD)，可用於酸性氣體的自動吸收採樣，針對氫氟酸、鹽酸和硝酸三種氣體 吸收效率幾乎可達100%；而另一個開發成功的單極的濕式靜電集塵器(WEP)，對直徑 16.8~615 nm 微粒的收集效率可達96.9~99.7%，且收集效率不受收集電極板上的微粒負 荷的影響。本計劃擬利用以上的PPWD 及WEP 的技術，結合雙頻道離子層析儀作成一 個準確性高的無機PM2.5 微粒與其前趨氣體的半連續監測系統，預計在三年之內完成系 統的設計、安裝、實驗室的校正測試，並利用人工的固氣分離器在大氣環境中進行此自 動監測器的驗證工作。

Taiwan EPA is currently planning for the PM2.5 control strategy and will establish the PM2.5 ambient air quality standard in the next several years. Therefore, it is important to monitor ambient aerosol particles and their precursor gases in real time to provide useful data for understanding PM2.5 sources, and establishing an effective control strategy. The commercial gas-particle monitors are expensive, which costs from 5 ~ 6 million NT per unit and the assessment report of the US EPA indicated that the accuracy of these monitors required further validation. Therefore, further research and development of the real time monitors are needed. Our research team has made use of sand-blasted, TiO2 nanoparticles coated parallel plates having super-hydrophilicity to develop a parallel plate wet denuder (PPWD) successfully. The PPWD is used for automatic acid gas sampling, and the absorption efficiency for HF, HNO3 and HCl was shown to reach nearly 100 %. A single stage wet electrostatic precipitator (WEP) was also developed which has the collection efficiency ranging from 96.9~99.7% for particles of 16.8~615 nm in diameter. There is no influence of particle loading on the collection plates on the collection efficiency. This project will integrate the above PPWD and WEP techniques with a dual channel ion chromatography to develop a semi-continuous monitor for monitoring the ambient PM2.5 soluble ions and the precursor gases simultaneously. In the proposed three year period, this project is expected to finish the design and assembly, the calibration test in the laboratory, and the field validation by using manual denuder samplers in the ambient atmosphere.