個人氣相與氣膠相分離採樣器的研發

Development of a Personal Denuder Sampler

本研究研發一種新型個人固氣分離採樣器，可用於工作場所中酸性液滴及酸鹼氣體的同步採樣。本採樣器包括二階的慣性衝擊器及二階的多孔金屬型固氣分離器，整個採樣器以鐵氟龍製造，採樣流量為2 Lmin-1。由實驗結果可知，第一和第二階慣性衝擊器的50 %截取氣動直徑分別為9.5 μm 及2.0 μm。由多孔金屬片的微粒損失及氣體吸附實驗發現孔隙尺寸為100 μm，厚度為0.317 cm 的多孔金屬片對於微粒直徑為2.0 μm 以下的微粒損失量小，且氣體收集效率高，適合作為高濃度氣體採樣介質。利用多孔金屬片進行不同酸鹼氣體的吸附效率與容量實驗，測試氣體濃度分別為硝酸4.128 ppm、鹽酸9.821 ppm、氫氟酸6.057 ppm、氨氣100.831 ppm，溫度為30±3 ℃，相對溼度（RH）為80±5%。在測試時間為4 hr，結果顯示多孔金屬片的氣體吸附效率在90-100%之間，且有足夠的吸附容量來作為作業環境測定之用。多孔金屬片塗敷5 %Na2CO3 對HNO3、HCl、HF 的採集效率分別為91±0.26%、95.08±0.06%、100±0.04%，吸附容量分別為4.47 mg、7.2 mg、2.5 mg。另外，多孔金屬片塗敷4%檸檬酸時對NH3 的採集效率為96.39±0.13%，吸附容量為33.6mg。

A new personal denuder sampler has been designed to measure acid gases and particulates simultaneously in the workplace. The new personal sampler consists of a two-stage cascade impactor and a two-stage porous metal denuder. The entire personal sampler is made of Teflon and sampling flow rate is 2 Lmin-1. The experimental 50 % cutoff aerodynamic diameter for each stage impactor is 9.5 μm and 2.0 μm, respectively. The particle losses of the porous metal disc for particle small than 2.0 μm diameter are less than 10 %. Experimental results indicate that the disc of 100 μm in nominal pore size, 0.317 cm in thickness is suitable for acidic gas sampling because it has a high gas collection efficiency and low particle loss. The porous metal disc was tested for the gas collection efficiency and collection capacity at the gas concentration of 4.128 ppm, 9.821 ppm, 6.057 ppm and 100.831 ppm for HNO3, HCl, HF and NH3, respectively. The testing condition was 80±5 % in relative humidity and 30±3 ℃ in temperature. The test data suggest that the gas collection efficiency of porous metal disc is between 90 % and 100 % for 4 hr sampling period, and the adsorbing capacity is sufficient for the high concentration gas sampling in the workplace. Using 5 % sodium carbonate/glycerin coating on the porous metal disc, the collection efficiencies for HNO3, HCl and HF is 91±0.26 %, 95.08±0.06 % and 100±0.04 %, and the adsorbing capacity is 4.47 mg, 7.2 mg and 2.5 mg, respectively. The collection efficiency for NH3 for the porous metal disc with 4 % citric acid coating is 96.39±0.13 %, and the adsorbing capacity is 33.6 mg.