作業環境PAHs揮發性影響XAD微孔介質採樣吸附之研究

Influence of Volatility on the Collection of Vapor-phase PAHs with XAD Porous Adsorbent in Workplace Measurement

本研究藉由微孔介質「吸附相曲線」解析半揮發性有機物（S-VOC）吸附特性，及推估作業環境 XAD-4 採集 PAHs 採樣滯留體積（VR）與安全採樣體積（VS）。 實驗以薄層吸附裝置探討七種半揮發性 PAHs（三環：AcPy、AcP、Flu、PA、Ant；四環：Fl、Pyr） 微孔介質吸附特性。 研究結果顯示 XAD-4 微孔介質七種氣狀 PAHs 吸附滯留體積（VR）與化合物揮發性 （PL，過冷液蒸氣壓）保持良好相關性 （R2 ，0.900 ），XAD-4 單位吸附滯留體積 （Vg ；每克介質 VR 值） 範圍值 25.3~158.8 m3 ，隨 PAHs 揮發性降低 （環數增多） 其 Vg 值有明顯上升趨勢。 本研究顯示「吸附曲線」有助解析 S-VOCs 吸附特性，常溫下 S-VOCs 化合物揮發性本質是影響微孔介質吸附關鍵因子。 本研究另估算作業環境 XAD 採樣管 PAH 安全採樣體積（VS），依據 NIOSH 採樣方法（2 L/min）XAD-4 介質 300mg 或 600mg 採樣管，即使採集 24 小時其安全採樣體積（VS）明顯大於實際採樣體積（ V ） 不會有破出疑慮。 而本研究針對 S-VOCs 吸附機制與估算其採樣安全體積之探討，已為未來作業環境相關 S-VOC 採樣吸附討論奠定良好的研究基礎。

This investigation studies the collection retention of polycyclic aromatic hydrocarbons (PAHs) from a common XAD-4 adsorbent for evaluating vapor-phase PAH sampling efficiency in workplace measurement. Laboratory examinations using frontal adsorption curves were conducted to explore the collection efficiency of seven PAH vapors--acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene--by XAD-4 resin. The results demonstrated a linear regression of retention volumes (VR) versus vapor pressure of the compounds. (PL) for the adsorption of seven PAHs on XAD-4 adsorbent showed a good correlation (R2, 0.900) The specific retention volumes of PAHs (Vg,VR/w, w = weight of adsorbent) increased with decreasing volatility of the compounds at 20 ℃ ( Vg ranging from 25.3 ~158.8 M3 ). The study revealed that the frontal adsorption approach was helpful in interpreting adsorption characteristics of PAHs with XAD-4 porous adsorbent. Meanwhile, volatility of the compound was a dominant factor in the adsorption of semi-volatile organic compounds (S-VOCs) at ambient temperature conditions (20 ℃ ) Based on the NIOSH sampling method for workplace measurement, a safe sampling volume (VS) of XAD-4 adsorbent (in the amounts of 300 and 600 mg) relating the theoretical plates of frontal chromatography (N) to adsorptive retention volume (VR) of the seven PAHs at 95% and 99% collection efficiencies was estimated.