High temperature ultralow water content carbon dioxide-in-water foam stabilized with viscoelastic zwitterionic surfactants

by Alzobaidi, S; Da, C; Tran, V; Prodanovic, M; Johnston, KP

Journal of Colloid and Interface Science; FEB 15 2017; Volume: 488; Pages: 79-91; DOI: 10.1016/j.jcis.2016.10.054

Ultralow water content carbon dioxide-in-water (C/W) foams with gas phase volume fractions (phi) above 0.95 (that is <0.05 water) tend to be inherently unstable given that the large capillary pressures that cause the lamellar films to thin. Herein, we demonstrate that these C/W foams may be stabilized with viscoelastic aqueous phases formed with a single zwitterionic surfactant at a concentration of only 1% (w/v) in DI water and over a wide range of salinity. Moreover, they are stable with a foam quality phi up to 0.98 even for temperatures up to 120 degrees C. The properties of aqueous viscoelastic solutions and foams containing these solutions are examined for a series of zwitterionic amidopropylcarbobetaines, R-ONHC3H6N(CH3)(2)CH2CO2, where R is varied from C12-14 (coco) to C-18 (oleyl) to C-22 (erucyl). For the surfactants with long C-18 and C-22 tails, the relaxation times from complex rheology indicate the presence of viscoelastic wormlike micelles over a wide range in salinity and pH, given the high surfactant packing fraction. The apparent viscosities of these ultralow water content foams reached more than 120 cP with stabilities more than 30-fold over those for foams formed with the non-viscoelastic C12-14 surfactant. At 90 degrees C, the foam morphology was composed of similar to 35 mu m diameter bubbles with a polyhedral texture. The apparent foam viscosity typically increased with phi, and then dropped at phi values higher than 0.95-0.98. The Ostwald ripening rate was slower for foams with viscoelastic versus non-viscoelastic lamellae as shown by optical microscopy, as a consequence of slower lamellar drainage rates. The ability to achieve high stabilities for ultralow water content C/W foams over a wide temperature range is of interest in various technologies including polymer and materials science, CO2 enhanced oil recovery, CO2 sequestration (by greater control of the CO2 flow patterns), and possibly even hydraulic fracturing with minimal use of water to reduce the requirements for wastewater disposal

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