A MULTIPLE PARALLEL-PLATE WETTED SCREEN DIFFUSION DENUDER FOR HIGH-FLOW AIR SAMPLING APPLICATIONS

Diffusion denuders are commonly used today for air sampling applicatio ns where it is necessary to discriminate between gaseous-and aerosol-p hase analytes. in some applications, such as isotopic analysis, it is necessarq'to collect a sufficient analyte mass necessitating high samp ling rates. Wetted denuders are preferred in many applications because they can be readily coupled to automated continuous analysis systems. We describe here a-compact (5 cm diameter, 30 cm length) diffusion de nuder with 11 individually wetted parallel screens (with an wetted are a in excess of 0.1 m(2)) that allow operation at high now rates. The e ffluent liquid is collected at the bottom from two V-shaped grooves. W ith SO2 as the test gas, similar to 95% is collected even at a now rat e of 50 L/min with very low particle losses.