An absorber is provided which uses a liquid solvent formed into a myriad of bubbles and micro-droplets. The solvent froth is a solvent for a selected component in an incoming gas stream. A plurality of spaced apart screen assemblies is placed in a reaction vessel. Using screens having cross-sections that are substantially rectangular wave in design together with proper operating parameters, the phenomenon of solvent plug pulsing is induced and maintained, maximizing efficiency of the absorber.