Morphology of Colloidal Gas Aphrons: Is There an Aqueous Shell? Laurent Pilon, Mechanical and Aerospace Engineering Department, University of California Los Angeles Colloidal gas aphrons (CGA) consists of closely packed minute spherical gas bubbles with diameter ranging from 10 to 100 microns and porosity of up to 70%. It can be used in various applications such as oil recovery and bioremediation of contaminated soils and waters. Numerous speculations have been proposed to explain their unusual stability and their rheology: The most commonly accepted structure consists of a gas core encapsulated into an aqueous shell stabilized by several layers of surfactants. No direct observation of this structure has been reported. CGA were described as “flowing like water” but no quantitative measurements have been made to confirm this statement. The objectives of the project are To non-invasively and unequivocally determine the morphology of CGA bubbles using light scattering measurements and depolarization. To measure and model the rheological properties of CGA for different pipe diameters and surfactant concentrations. Notable outcomes from this study include, Assembly and testing of an experimental setup for polarization and scattering measurements. Determination of the rheological properties of CGA flowing through minichannels. Surfactants Liquid shell gas bulk water Suspected structure CGA rheology Scattering and polarization setup