Surface modified annular wet denuder for the collection of water-soluble trace gases

Abstract

An annular wet denuder with both annular surfaces functioning as a sink for gaseous molecules is described. A gas absorbing solution was continuously flowed down the stainless-steel inner tube exterior and the outer tube interior gas collection surfaces of the denuder. In order to enhance the gas collection efficiency, the gas collection surfaces were modified with a Nylon monofilament and a perfluoroalkoxy alkane screen mesh cloth. The collection efficiency was increased by coiling the monofilament around the inner tube exterior, and by fixing the screen mesh cloth on the outer tube interior (e.g. 1.67 ± 0.06 and 1.77 ± 0.01 times at a gas absorbing solution flow rate of 0.30 cm³ min⁻¹ tube⁻¹, respectively). At a sampling flow rate of 1.0 dm³ min⁻¹, 97.7 ± 0.53% of the trace gas was collected with the surface modified annular wet denuder. The response speeds of the analytical signal change (10% → 90% and 90% → 10%) were 5.0 ± 0.9 min and 4.4 ± 0.2 min, respectively. Quantitative collection of water-soluble trace gas and reasonably rapid response time were achieved with the developed device.