Conformational changes influence clogging behavior of micrometer-sized microgels in idealized multiple constrictions

Abstract

Clogging of porous media by soft particles has become a subject of extensive research in the last years and the understanding of the clogging mechanisms is of great importance for process optimization. The rise in the utilization of microfluidic devices brought the possibility to simulate membrane filtration and perform in situ observations of the pore clogging mechanisms with the aid of high speed cameras. In this work, we use microfluidic devices composed by an array of parallel channels to observe the clogging behavior of micrometer sized microgels. It is important to note that the microgels are larger than the pores/constrictions. We quantify the clog propensity in relation to the clogging position and particle size and find that the majority of the microgels clog at the first constriction independently of particle size and constriction entrance angle. We also quantify the variations in shape and volume (2D projection) of the microgels in relation to particle size and constriction entrance angle. We find that the degree of deformation increases with particle size and is dependent of constriction entrance angle, whereas, changes in volume do not depend on entrance angle.

Microtechnological Tools to Achieve Sustainable Food Processes, Products, and Ingredients

“…The scale at which these devices can be made is typically slightly larger than the dimensions of membrane pores, but the gap is closing fast. For example, particle migration in a narrow channel [126,138] and pore clogging were tested both for hard [59,139] and soft particles [15] using pores that were typically 20 μm wide.…”

“…When working with soft particles using exactly the same devices used previously, the situation becomes more complex. In the research of Bouhid de Aguiar [15,16], soft particles that were close to many food ingredients were tested and unexpected behavior was recorded, as illustrated in the top right panel in Fig. 5.…”

“…For gel particles that are relatively large (25-40 μm), both deformation and water expulsion play a role in reducing the width of the particle and allowing permeation. For gel particles as they typically occur in foods and that are smaller (typically below 5 μm), water expulsion is expected to be the main mechanism [15,16].…”

“…In the top left panel (a) schematic of the pore constrictions [127]. Top right (b), a deformable particle passing through a pore [15]. Bottom left (c): three images of the cake thickness measured at different cross-flow velocities (0, 0.2, and 0.4 mL/min).…”

Particle Movements Provoke Avalanche-like Compaction in Soft Colloid Filter Cakes

“…[25][26][27] In contrast to hard particles, soft particles can adapt to the pore geometries by deforming and, therefore, show a smaller pore-blocking tendency. 28,29 The microfluidic observation method was applied for pore phenomena and for studying the filter cake in a fouling layer. Different studies investigate the influence of the cake morphology on permeation, 30,31 the deformation of single microgels during cake compression, 11 and the relaxation and removal of filter cakes by backflushing.…”