Experimental investigation of pore clogging by microparticles: Evidence for a critical flux density of particle yielding arches and deposits

Agbangla, Gbedo Constant; Climent, Éric; Bacchin, Patrice

doi:10.1016/j.seppur.2012.09.011

Cited by 90 publications

(70 citation statements)

References 16 publications

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“…Preliminary experiments have been performed by varying the concentration in KCl in the solution where particles are dispersed. These first experiments have confirmed the importance of this parameter on the capture efficiency that has already been discussed (Agbangla et al 2012). Only a few captures of particles are observed after 2 h of filtration when particles are dispersed in ultrapure water in all the geometries presented in this paper, whereas fouling is observed when processing with particles diluted in 10 -1 M KCl solution (concentration chosen in order to reduce the magnitude of repulsion between particles without having particle aggregation).…”

Section: Experiments On Microseparatorssupporting

confidence: 85%

“…It is here an additional effect of the inherent increase due to the increase in the particle flux density. Similar observations have been made with straight channels by (Agbangla et al 2012) who defined a critical flux density of particle yielding arches and deposits. Such a phenomenon could be explained by the theory used to Fig.…”

Section: Effect Of the Fluid Velocitysupporting

confidence: 77%

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Clogging of microporous channels networks: role of connectivity and tortuosity

Bacchin

Derekx

Veyret

et al. 2013

Microfluid Nanofluid

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The aim of this work is to study the pore blocking by the use of microfluidic devices (microseparators) and numerical simulation approaches. The microseparators are made in PDMS and are constituted of an array of microchannels 20 lm wide with three types of structure: straight microchannels, connected microchannels (or aligned square pillars) and staggered square pillars in order to mimic merely the complexity of the flow encountered in filters or membranes (tortuosity, connectivity between pores). Direct observation with video microscopy of filtrations of 5 lm latex particles has been performed to examine the capture of particles. The results show a piling up of particles within the porous media leading to a clogging. The capture efficiency remains low (\0.1 %). In the case of filtration in the forest of pillars, the capture is faster and arises mainly between the pillars. The increase in tortuosity in the microseparator leads then to a rise of the clogging. It must be caused by the increase in critical trajectories leading to the capture of particles on the PDMS walls. At the same time, numerical simulations of filtration in parallel with microchannels have been performed in the same flow conditions with GeoDict software. The different kind of experimental deposit structure can be simulated, but there is still inaccuracy in the description of the accumulation kinetics. These discrepancies are probably due to the lack of accuracy to depict particle/particle colloidal interactions in simulations and the fact that re-suspension of particles after capture is not well described.

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Section: Experiments On Microseparatorssupporting

confidence: 85%

Section: Effect Of the Fluid Velocitysupporting

confidence: 77%

Clogging of microporous channels networks: role of connectivity and tortuosity

Bacchin

Derekx

Veyret

et al. 2013

Microfluid Nanofluid

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“…Typically, the particle diameter equals 5 lm and the channel width 20 lm which matches our earlier experimental conditions [10]. Fluid flow is laminar in all simulations (channel Reynolds number is equal Oð10 À2 )).…”

Section: Configuration Of 3d Channel Simulationsupporting

confidence: 64%

“…This mechanism has been clearly identified by Ramachandran and Fogler [6] when they studied the conditions under which multilayer deposition occurs in a microchannel. In a previous experimental work [10], we demonstrated with microfluidic experiments that very different clogging structures (arches, deposit, dendrites) can be observed in flows of micrometric particles in microchannels. These different structures depend on the hydrodynamic conditions, the particle concentration and the surface interaction magnitude.…”

Section: Introductionmentioning

confidence: 90%

Numerical investigation of channel blockage by flowing microparticles

2014

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a b s t r a c tThe dynamic formation of 3D structures of microparticle aggregates blocking the flow through straight microchannels is investigated by direct numerical simulation of the coupled motion of particles and fluid. We use the Force Coupling Method to handle simultaneously multibody hydrodynamic interactions of confined flowing suspension together with particle-particle and particle-wall surface interactions leading to adhesion and aggregation of particles. The basic idea of the Force Coupling Method relies on a multipole expansion of forcing terms (added to the Navier-Stokes equations) accounting for the velocity perturbation induced by the presence of particles in the fluid flow. When a particle reaches the wall or an attached particle, we consider that the adhesion is irreversible and this particle remains fixed. We investigate the kinetics of the microchannel blockage for several solid volumetric concentrations and different surface interaction forces. Many physical quantities such as the temporal evolution of the bulk permeability, capture efficiency, modification of the fluid flow and forces acting on attached particles are analyzed. We show that physical-chemical interactions, modeled by DLVO forces, are essential features which control the blockage dynamics and aggregate structure. IntroductionThe physics of transport, deposition, detachment and reentrainment of colloidal particles suspended in a fluid are of major interest in many areas of fluids engineering: fouling of heat exchangers, contamination of nuclear reactors, plugging of filtration membranes and occlusion of human veins, deposits in microelectronics and in the paper industry. In many solid/liquid separation processes such as micro-filtration or ultrafiltration of water, the limitation of the process performance is related to the fouling of filtration devices. To prevent or control the occurrence of fouling, it is necessary to achieve a better understanding of the respective roles of physical-chemical phenomena and hydrodynamic interactions in a confined suspension of particles. Non-hydrodynamic surface interactions and the adhesion of particles onto solid surfaces are the essential features to be modeled. However, mainly because of a complex interplay between the hydrodynamics of the flow, the physical-chemical properties of the filtered suspensions (often in a colloidal state) and the nature of the solid material, predicting fouling dynamics is still challenging.Different experimental techniques and numerical approaches have been developed to achieve new insights on the local structure of particle aggregates and the kinetics of blockage. Sharp and Adrian [4], by means of experiments in microtubes, observed blockage due to arch formation. The experiments were performed using liquids seeded with polystyrene beads at low volumetric concentration. They showed that a stable balance between the hydrodynamic forces and contact forces (mainly solid friction) between particles and the wall provokes the formation of arches. Wyss et al.[5] stu...

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“…Conversely, when filtered in such microsystems, "inert" particles with the same "particle"/microchannel size ratio (2/10 for bacteria and 5/20 for latex particles) accumulate on the pillars constituting the wall of microchannels to form dendrites (Fig. 5(c)) that can lead to the formation of dense deposits in the upstream zone (Agbangla et al, 2012). Particles are then captured in low velocities zone (hydrodynamic stagnation point in the pillars) but are not accumulated in areas where the flow is important (or, to be more precise, if particles are deposited at these locations the importance of the flow leads to their immediate detachment and reentrainment in the flow).…”

Section: A Formation Of Bacteria Streamers: Experimental Evidence Anmentioning

confidence: 99%

Impact of tortuous flow on bacteria streamer development in microfluidic system during filtration

et al. 2014

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The way in which bacterial communities colonize flow in porous media is of importance, but basic knowledge on the dynamic of these phenomena is still missing. The aim of this work is to develop microfluidic experiments in order to progress in the understanding of bacteria capture in filters and membranes. PDMS microfluidic devices mimicking filtration processes have been developed to allow a direct dynamic observation of bacteria across 10 or 20 lm width microchannels. When filtered in such devices, bacteria behave surprisingly: Escherichia coli, Pseudomonas aeruginosa or Staphylococcus aureus accumulate in the downstream zone of the filter and form large streamers which oscillate in the flow. In this study, streamer formation is put in evidence for bacteria suspension in non nutritive conditions in less than 1 h. This result is totally different from the one observed in same system with "inert" particles or dead bacteria which are captured in the bottleneck zone and are accumulated in the upstream zone. Observations within different flow geometries (straight channels, connected channels, and staggered row pillars) show that the bacteria streamer development is influenced by the flow configuration and, particularly by the presence of tortuosity within the microchannels zone. These results are discussed at the light of 3D flow simulations. In confined systems and in laminar flow, there is secondary flow (z-velocities) superimposed to the streamwise motion (in xy plane). The presence of the secondary flow in the microsystems has an effect on the bacterial adhesion. A scenario in three steps is established to describe the formation of the streamers and to explain the positive effect of tortuous flow on the development kinetics. V C 2014 AIP Publishing LLC. [http://dx

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Experimental investigation of pore clogging by microparticles: Evidence for a critical flux density of particle yielding arches and deposits

Cited by 90 publications

References 16 publications

Clogging of microporous channels networks: role of connectivity and tortuosity

Clogging of microporous channels networks: role of connectivity and tortuosity

Numerical investigation of channel blockage by flowing microparticles

Impact of tortuous flow on bacteria streamer development in microfluidic system during filtration

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