Accumulation of Colloidal Particles in Flow Junctions Induced by Fluid Flow and Diffusiophoresis

Abstract

The flow of solutions containing solutes and colloidal particles in porous media is widely found in systems including underground aquifers, hydraulic fractures, estuarine or coastal habitats, water filtration systems, etc. In such systems, solute gradients occur when there is a local change in the solute concentration. While the effects of solute gradients have been found to be important for many applications, we observe an unexpected colloidal behavior in porous media driven by the combination of solute gradients and the fluid flow. When two flows with different solute concentrations are in contact near a junction, a sharp solute gradient is formed at the interface, which may allow strong diffusiophoresis of the particles directed against the flow. Consequently, the particles accumulate near the pore entrance, rapidly approaching the packing limit. These colloidal dynamics have important implications for the clogging of a porous medium, where particles that are orders of magnitude smaller than the pore width can accumulate and block the pores within a short period of time. We also show that this effect can be exploited as a useful tool for preconcentrating biomolecules for rapid bioassays.

Stratification of mixtures in evaporating liquid films occurs only for a range of volume fractions of the smaller component

“…3(b) converge on each other and on the yellow line marking the descending front. Similar localisation of particles due to diffusiophoresis is seen in systems where diffusiophoresis is due to salt gradients 24,26,40,41 . There this convergence is called focusing.…”

Cleaning by Surfactant Gradients: Particulate Removal from Porous Materials and the Significance of Rinsing in Laundry Detergency

“…Similar principles have been applied to design 'salt traps' [11] and 'soluto-inertial beacons' [12]. Diffusiophoresis has been proposed as an inexpensive way to measure zeta potentials [13]; it can be induced by gas dissociation and exploited as a continuous separation process [14]; and in the presence of an opposing flow can lead to rapid pore blocking [15].…”

Solar vapor generation optimization of a carbon‐black/wood‐flour system with strength enhanced by polystyrene

“…After system working for 4 hours, there is a serious crystalline‐salt deposition on the system surface and the evaporation rate of the system was decreased to 1.2 kg ∙ m −2 ∙ h −1 , which may be attributed to the negative effects of the weakened light capture ability of the top surface and also hindered emission of water vapor because of the accumulation of salt crystals in pores of the system . Despite all this, stability characterization of the system in Section 3.2 ensures that physical cleaning could be used to remove these deposited salts. Moreover, concentrations of four main irons (Na + , K + , Mg + , and Ca + ) were compared between the seawater and the condensate water, as shown in Figure 7C.…”