Experiments on transport of hydrophobic particles and gas bubbles in porous media

Abstract

Adhesion of hydrophobic colloids (clay minerals) on the surface of bubbles of air and the transport of the composite units formed by bubbles and mineral particles were observed in a glass micro model.When a clay mineral suspension flowed in a porous medium that contained bubbles of air trapped in small pores, particles accumulated preferentially on the upstream portion of the bubbles, and quasi-stable bubble-mineral particle units were formed. With an increase in the flow velocity, the particles moved along the interface between the bubble and the liquid and accumulated on the downstream portion of the bubbles. A large stress could mobilize the units which, occasionally, accumulated in larger voids.The mechanism suggested is adhesion of the particles on the surface of the bubble due to compression of their diffuse electrical double layer. The adsorbed particles can be moved by shear stresses which act in the region of water molecules between the well-organized layers of water on the surfaces of the bubble and the clay particles. A large enough shear stress causes the bubbles to become more streamlined, allowing them to move in the channel system. If in contact, the common lamina of the bubbles can withdraw and rupture.Bubbles transport from 20 to 50 times more particles than can be transported by average suspension.

Surface and interfacial tensions of aqueous dispersions of charged colloidal (clay) particles

“…From this point of view one might conclude that the montmorillonite particles tend to be negatively adsorbed while the kaolinite particles tend to positively adsorb. This is consistent with a study of adhesion of small particles to large air bubbles in suspensions by Goldenberg et al (18). They found that in dilute electrolyte solutions clays of low cation exchange capacity (kaolinite) adhered to bubble surfaces and formed surface structures.…”

“…Menon et al (12)(13)(14)(15)(16)(17) have published several accounts of their investigations of emulsions stabilized by finely divided solids; these papers provide convincing evidence that such solids can have important effects on interfacial tensions. Finally, we note that Goldenberg et al (18) have reported on the effects of suspended clays on transport in porous media containing gas bubbles.…”

Partitioning of Clay Colloids at Air–Water Interfaces

“…For instance, enrichment of colloid-associated heavy metals and organic compounds at the surface of oceans and lakes have been reported (1)(2)(3)(4). Clays, humic acids, and microorganisms have also been found preferentially sorbed at air-water interfaces in unsaturated soils (5)(6)(7)(8)(9). Colloid partitioning at gas-water interfaces has been analyzed as a special case of heterocoagulation, the interaction between double-layers of dissimilar surfaces (10,11).…”

Comparison of Hanford Colloids and Kaolinite Transport in Porous Media

“…Colloid deposition kinetics in natural and model porous media have been studied as a function of colloid size, colloid type, surface properties, flow velocity, water content, pore size, and solution chemistry (Goldenberg et al, 1989; Elimelech and O'Melia, 1990a, 1990b; McDowell‐Boyer, 1992; Wan and Tokunaga, 1997; James and Chrysikopoulos, 2000; Gamerdinger and Kaplan, 2001; Lenhart and Saiers, 2002). Although great advancements have been made in the study of colloid reaction and transport in porous media, both theoretically and experimentally, our understanding of colloid–soil interactions and our ability to predict transport of colloids in natural subsurface media are limited.…”