Components, usually but not exclusively gaseous components, are removed in a liquid medium from gas streams and chemically converted into an insoluble phase or physically removed. Specifically, hydrogen sulfide may be removed from gas streams by oxidation in aqueous chelated transition metal solution in a modified agitated flotation cell. The same principal may be employed in other procedures in which a gaseous phase is dispersed in a liquid phase to effect an interaction between components present in such phases. A gas-liquid contact apparatus, generally a combined chemical reactor and solid product separation device, comprising such modified agitated flotation cell is also described. In order to effect mass transfer and rapid reaction gas bubbles containing hydrogen sulfide and oxygen are formed by rotating an impeller at a blade tip velocity of at least about 350 in/sec. to achieve the required shear. To assist in the reaction, a surrounding shroud has a plurality of openings, generally of aspect ratio of approximately 1, of equal diameter and arranged in uniform pattern, such as to provide a gas flow therethrough less than about 0.02 lb/min/opening in the shroud. In general, the gas velocity index of gas through the openings in the shroud is at least about 18 per second per opening. Each of the openings has an area corresponding to an equivalent diameter of less than about one inch.