尼龍濾紙對鹽酸及硝酸氣體吸附能力的研究

A Study of Nylon Filter in Adsorbing HCl and HNO3 Gases

本研究探討圓環型氣相與氣膠相分離採樣系統中尼龍濾紙（Nylasorb membrane，47 mm diameter， 1.0µm pore size，Gelman Laboratory，USA）是否具有足夠的吸附容量來吸附硝酸及鹽酸氣體；以及在鹽酸和硝酸氣體同時存在的條件下進行干擾測試並且進行理論計算。結果顯示，在溫度為 30 ± 2℃及相對濕度分別為 20 ± 5%、55 ± 5%及 80 ± 5%的操作條件下，尼龍濾紙對鹽酸氣體的吸附容量分別為 8µg、160µg 及 240µg；尼龍濾紙對硝酸氣體的吸附容量分別為 160µg、1400µg 及 1900µg。尼龍濾紙對硝酸氣體的吸附容量遠大於尼龍濾紙對鹽酸氣體的吸附容量，因此尼龍濾紙對硝酸氣體具較佳的吸附能力。 在尼龍濾紙同時吸附鹽酸及硝酸氣體的干擾實驗方面，實驗結果發現尼龍濾紙在有硝酸氣體的干擾下，會導致其對鹽酸氣體的吸附效率降低，尤其在濕度小於 25%或高容量（2000µg）的硝酸氣體干擾情況下，干擾現象更是顯著，吸附效率最低降至 35%；而尼龍濾紙在有鹽酸氣體的干擾下，對硝酸氣體的吸附效率沒有明顯的干擾現象。本研究利用理論模式進一步計算尼龍濾紙在不同硝酸氣體的干擾量下對鹽酸氣體的收集效率的關係。結果顯示，隨著硝酸氣體的干擾量增加，尼龍濾紙對鹽酸氣體的收集效率會明顯降低。此外，隨著相對濕度的提高，硝酸氣體對尼龍濾紙吸附鹽酸氣體的干擾現象會越來越不明顯。

The objective of this study is to investigate whether the nylon filter (Nylasorb membrane, 47 mm diameter, 1.0μm pore size, Gelman Laboratory, USA) of an annular denuder system has enough capacity to adsorb HCl and HNO3 gases evaporated from the particles on the Teflon filter. Collection capacity tests of the nylon filter in adsorbing individual HCl or HNO3 gas, interference test of the nylon filter to adsorb mixed HCl and HNO3 gases have been studied. In the collection capacity tests of the nylon filter, the testing temperature is 30 ± 2℃ and the relative humidity is 20 ± 5%, 55 ± 5% and 80 ± 5%, respectively. Under the humidity test conditions, the data indicates the capacity of the nylon filter in adsorbing HCl gas is 8μg、160μg、240μg and that for HNO3 gas is 160μg、1400μg、1900μg, respectively. The capacity of the nylon filter to adsorb HNO3 gas is much higher than that for HCl gas. In the interference test of the nylon filter, the experiment data show that the collection efficiency of HCl gas decreases substantially when HNO3 coexists. The collection efficiency is reduced to as little as 35% when the testing relative humidity is 20 ±5 % or HNO3 (2000μg). However, there is no significant effect for the nylon filter in adsorbing HNO3 when HCl coexists with the collection efficiency greater than 95%. In this study, the mono-layer adsorption theory was used to estimate the theoretical capacity of the nylon filter in adsorbing HCl gas when HNO3 gas coexists. The results showed that the collection efficiency of HCl gas decreases with an increasing interference of HNO3 gas. The effect of the interference of HNO3 gas on the collection efficiency of HCl gas is negligible when the relative humidity is high.