Nanoparticle-stabilized carbon dioxide-in-water foams with fine texture

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• 作者：Andrew J. Worthen^a ; Hitesh G. Bagaria^a ; Yunshen Chen^a ; Steven L. Bryant^b ; Chun Huh^b ; Keith P. Johnston^a ; ^{kpj@che.utexas.edu}
• 关键词：Emulsion ; Foam ; Carbon dioxide ; Nanoparticle ; Hydrophilic/CO2-philic balance ; Viscosity
• 刊名：Journal of Colloid and Interface Science
• 出版年：2013
• 出版时间：1 February, 2013
• 年：2013
• 卷：391
• 期：Complete
• 页码：142-151
• 全文大小：1125 K

文摘

The concept of hydrophilic/CO₂-philic balance (HCB) was extended to describe stabilization of carbon dioxide-in-water (C/W) foams (also called emulsions) with silica nanoparticles adsorbed at the CO₂-water interface. Opaque, white C/W foams (bubble diameter <100 ¦Ìm) were generated with either PEG-coated silica or methylsilyl modified silica nanoparticles in a beadpack with CO₂ densities between 0.2 and 0.9 g mL^?1. For methylsilyl modified silica nanoparticles, 50 % SiOH modification provided an optimal HCB for generation and stabilization of viscous C/W foams with high stability. The apparent viscosity measured with a capillary tube viscometer reached 120-fold that of a CO₂-water mixture without nanoparticles, a consequence of the small bubble size and the energy required to deform a high density of aqueous lamellae between CO₂ bubbles. Air-in-water (A/W) foams stabilized with nanoparticles were used to gain insight into the relationship between nanoparticle surface properties and adsorption of the nanoparticles at various types of interfaces. With suitable nanoparticles, A/W foams were stable for at least 7 days and C/W foams were stable for at least 23 h. The ability to achieve long term stability for nanoparticle stabilized C/W foams could offer an alternative to conventional surfactants, which are known to have much lower adsorption energies.