Ammonia (NH3) is readily scrubbed using Jet Venturi, Packed Towers, or Multi-channel Bed Scrubbers. Although ammonia is infinitely soluble in water, recirculating an aqueous NH3 solution cannot generally be used for scrubbing. Aqueous NH3 solutions are characterized by relatively high NH3 vapor pressures that prevent the mass transfer of NH3 from gas to liquid phase. Commonly NH3 is scrubbed with an aqueous acid solution. Sulfuric acid or phosphoric acid are often chosen because of their own relatively low vapor pressure. However, nitric acid can also be used and does generate a potentially usable product for agricultural use.
Amines are also scrubbed with aqueous acids. However, amines tend to be more difficult to scrub then ammonia. The characteristics of the particular amine (solubility in water, reactivity with acid, etc.) determine how successful or difficult the scrubbing will be.