Membrane-Based Parallel Plate Denuder for the Collection and Removal of Soluble Atmospheric Gases

Abstract

A continuously wetted cellulose acetate membrane-based parallel plate diffusion denuder is described. This is the first membrane-based denuder that has a small enough internal liquid holdup volume to permit reasonably rapid response time (10 --> 90% rise time of approximately 1.2 min for a transient event at a liquid flow rate of 500 microL/min) while permitting quantitative removal of common soluble atmospheric trace gases at flow rates up to 1.7 L/min. The latter attribute permits the use of the device as the first element in a particle sampling and analysis system for the quantitative removal of potentially interfering soluble trace gases. Particle losses in the denuder range from 0.9 to 2.9% over an aerodynamic diameter range of 0.38-3.48 microm, averaging 1.8%. However, only approximately 0.5% of the particles actually appears in the denuder effluent liquid. The relatively compact (300 mm H x 57 mm W x 26 mm D) wet denuder should be attractive in a number of applications. We show excellent agreement for HONO measurements with a conventional larger parallel plate wetted denuder in field measurements.

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

“…The detection limit was 0.15 ppb, estimated from 3σ of the lowest working standard. Specific analytical characteristics are described in Simon and Dasgupta (1995) and Takeuchi et al (2004).…”

A Comparison Between a Semi-Continuous Analyzer and Filter-Based Method for Measuring Anion and Cation Concentrations in PM10at an Urban Background Site in London

“…The sample passes adjacent to a membrane-based liquid diffusion denuder (Takeuchi et al 2004), where interfering acidic and basic gases are removed by using a 5.5 mM of H 2 O 2 solution. In order to achieve high collection efficiencies, the particle-laden air stream next enters the aerosol super saturation chamber to enhance particle growth.…”

“…A total flow of 16.7 l/ min was drawn into the system and a flow splitter installed before the denuder to allow 3 l/min flow into the sampler. The penetration efficiency of the denuder has been tested for particles of aerodynamic diameter range of 0.38 to 3.48 mm and at an air flow rate of 1 and 2 l/min, reporting a particle loss of 1.79% (Takeuchi et al 2004). The particle loss for larger aerodynamic diameters and higher flow rate is currently unknown.…”

Online measurements of water-soluble organic acids in the gas and aerosol phase from the photooxidation of 1,3,5-trimethylbenzene

“…The sampling of the gas and particle phase for the IC system was done with a wet effluent diffusion denuder (WEDD) and an aerosol collector (AC), respectively (Takeuchi et al, 2004(Takeuchi et al, , 2005. The WEDD part is connected with a Teflon ® inlet to the smog chamber.…”