NOVELTY - A novel method for forming and coalescing gas containing aphrons in an aqueous liquid comprising a dispersant which changes reversibly to hydrophobic, hydrophilic, or amphiphilic in response to a change in condition of the aqueous liquid, to cause formation and coalescence of gas containing aphrons (microbubbles) in aqueous dispersions; and use in speeding up mass transfer of gases in processes.    USE - The method provides fine dispersions (aphrons) with large interactive surfaces to maximize mass transfer rates of gases (and with the wider disclosure, of liquids and solids), for reaction or phase transfer purposes, and which can be induced to coalesce rapidly for easy separation when dispersion is no longer required. For gases, this relates particularly to foam formation and disappearance. Examples of applications to gases include aeration and oxygenation of fermentations and waste treatment processes, notably soil aeration to enhance bioremediation, limited biomass aeration to provide synthesis gas (H2/CO) and its reaction applications, gas scrubbing to remove a particular gas, and flotation and foam fractionation for separation of colloidal materials, e.g., organic and metal ions from aqueous liquids. Apart from gas dispersions as in the claims, the method is operable with all kinds of chemical or biotechnological reaction and extraction processes in which two phases are involved. Polymeric emulsifiers are used in a variety of areas including aqueous cleaning, food, cosmetics, pharmacy, agriculture, and bitumen processing. Actual operations mentioned include treatment of radioactive, hazardous, and mixed wastes, enzyme extraction and immobilization, stripping dilute solutes from aqueous phases, and apolar substrate delivery to aqueous systems. Suspension polymerization, to obtain copolymers of materials, e.g., acrylic and methacrylic acids, having hydrophobic oligomers, with hydrophilic second monomers, e.g., polyethylene glycol (PEG) monomer, without use of an organic solvent, is also mentioned.    ADVANTAGE - Processes are speeded up by the rapid dispersion and rapid coalescence to two distinct phases. The method is also less energy intensive than stirring only to provide mixing on a large scale, with a fifth power relationship between impeller diameter and energy to turn the impeller.    DETAILED DESCRIPTION - Method for forming and coalescing gas containing aphrons in an aqueous liquid reversibly, comprising:    (a) providing, in the aqueous phase, an emulsifier, surfactant, or their mixtures as dispersant and which is rendered hydrophobic, hydrophilic, or amphipathic reversibly, as a function of a change of conditions in the aqueous liquid which changes a physical structure of the dispersant;    (b) forming gas containing aphrons in the aqueous phase at a first condition in which the dispersant stabilizes the aphrons in the aqueous phase; and    (c) changing the conditions to coalesce the aphrons in the aqueous phase.    An INDEPENDENT CLAIM is also included for the composition, comprising gas containing aphrons in an aqueous liquid, in which the dispersant exhibits a change in properties as in the method above.