A Counter-Current Parallel-Plate Membrane Denuder for the Non-Specific Removal of Trace Gases

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• 作者：Pablo A. Ruiz ; Joy E. Lawrence ; Stephen T. Ferguson ; Jack M. Wolfson ; Petros Koutrakis
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：August 15, 2006
• 年：2006
• 卷：40
• 期：16
• 页码：5058 - 5063
• 全文大小：212K
• 年卷期：v.40,no.16(August 15, 2006)
• ISSN：1520-5851

文摘

In this paper we present a counter-current parallel-platemembrane diffusion denuder for the non-specific removal oftrace gases from an air flow. In this design, gaseouspollutants are removed by diffusing from a sample channelto two purge channels by crossing microporous membranes.In the laboratory, at a sample flow rate of 5 L/min andpurge flow rates of 5 L/min each, gas removal efficienciesranged from 84% for CO to 72% for SF₆. Removal efficienciesincreased with lower sample flow rate, a higher sampleto purge flow rate ratio, a longer channel length, and usingmolecules with higher diffusion coefficient. Removalefficiencies were, however, not affected by the samplechannel height. In addition, gas penetration was exponentiallyassociated with the product of channel length, diffusioncoefficient, and the inverse of sample flow rate. Particlelosses were significant (10-25% losses) only for particlessmaller than 50 nm. In a field evaluation, the denuder'sperformance was tested with an aerosol produced in aphotochemical chamber. The denuder's performance wassimilar to that observed in the laboratory and wasstable over time. Finally, the denuder was tested with asemivolatile organic aerosol. Particle mass losses due tovolatilization were about 30%.