Determination of Ammonia/Air Diffusion Coefficient Using Nafion Lined Tube

Trace gaseous ammonia in air was removed in a laminar flow Teflon tube lined with Nafion film. The ammonia deposition pattern was obtained by sectioning the Nafion lining, extracting with an aqueous solution, and measuring the concentration with an ammonia gas electrode. Mass transport analysis of the deposition pattern demonstrated that the ammonia was removed from the air stream at a rate controlled by gaseous diffusion. The ammonia/air diffusion coefficient equalled 0.228 ± 0.012 cm2 s−1 at 1 atm 25°C. No dependence on relative humidity was observed over the range 10–92%.