Porous membrane-based diffusion scrubber for the sampling of atmospheric gases

Abstract

A diffusion scrubber, employing a porous fluorocarbon membrane as the sampling tube and with a scrubber solution flowing into a narrow annular space exterior to the membrane, is described. The use of this diffusion scrubber with a dilute buffered formaldehyde solution as the scrubber solution has been exploited for collecting sulphur dioxide. Collection efficiencies are reported for sampling rates of up to 3 l min^–1. The response time to a SO₂ input pulse in the continuous analysis mode is demonstrated using dilute hydrogen peroxide as the scrubber solution and a conductivity detector. The advantages of a diffusion scrubber for collecting atmospheric gases are discussed. A simple inexpensive design of permeation tubes for standard gas sources is also reported.