title: Viscosity and stability of ultra-high internal phase CO2-in-water foams stabilized with surfactants and nanoparticles with or without polyelectrolytes.
abstract: To date, relatively few examples of ultra-high internal phase supercritical CO2-in-water foams (also referred to as macroemulsions) have been observed, despite interest in applications including "waterless" hydraulic fracturing in energy production. The viscosities and stabilities of foams up to 0.98 CO2 volume fraction were investigated in terms of foam bubble size, interfacial tension, and bulk and surface viscosity. The foams were stabilized with laurylamidopropyl betaine (LAPB) surfactant and silica nanoparticles (NPs), with and without partially hydrolyzed polyacrylamide (HPAM). For foams stabilized with mixture of LAPB and NPs, fine ∼70 μm bubbles and high viscosities on the order of 100 cP at>0.90 internal phase fraction were stabilized for hours to days. The surfactant reduces interfacial tension, and thus facilitates bubble generation and decreases the capillary pressure to reduce the drainage rate of the lamella. The LAPB, which is in the cationic protonated form, also attracts anionic NPs (and anionic HPAM in systems containing polymer) to the interface. The adsorbed NPs at the interface are shown to slow down Ostwald ripening (with or without polymer added) and increase foam stability. In systems with added HPAM, the increase in the bulk and surface viscosity of the aqueous phase further decreases the lamella drainage rate and inhibits coalescence of foams. Thus, the added polymer increases the foam viscosity by threefold. Scaling law analysis shows the viscosity of 0.90 volume fraction foams is inversely proportional to the bubble size.
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xue
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Andrew
authors.initials: A
authors.lastname: Worthen
authors.affiliation: Department of Petroleum and Geosystems Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Ali
authors.initials: A
authors.lastname: Qajar
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Isaiah
authors.initials: I
authors.lastname: Robert
authors.affiliation: Department of Petroleum and Geosystems Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Bryant
authors.affiliation: Department of Petroleum and Geosystems Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Chun
authors.initials: C
authors.lastname: Huh
authors.affiliation: Department of Petroleum and Geosystems Engineering, University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Maša
authors.initials: M
authors.lastname: Prodanović
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, United States. Electronic address: kpj@che.utexas.edu.
authors.forename: Keith P
authors.initials: KP
authors.lastname: Johnston
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D001622:Betaine / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry*; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001622:Betaine; D002245:Carbon Dioxide; D004573:Electrolytes; D013501:Surface-Active Agents; D014867:Water; D000099166:Polyacrylamides
keywords: CO(2)-in-water foam; Foam stability; High internal phase foam; Nanoparticle-stabilized foam; Viscosity