First-Principle Colloidal Gate for Controlling Liquid and Molecule Flow Using 2D Claylike Nanoparticles

Abstract

Herein, we exploit the natural tendency of two-dimensional (2D) clay nanoparticles to self-assemble and restrict water permeability in soils to fabricate a first of its kind synthetic, pH-activated, reversible, and tunable colloidal flow gate. To realize this, we studied the effect of the pH level of a suspension of claylike layered double hydroxide (LDH) nanoparticles on the LDH coagulation process. We then packed the LDH into a fixed-bed column and examined the effect of pH on mass transport through the column. We found that the 2D platelike LDH particles coagulate in an edge-to-edge configuration, which renders highly nonisotropic aggregates, pivotal for obstructing the transport of liquid and molecules therein. We showed that the coagulation and flow through the column may be regulated by imposing various pH levels as an external stimulus to affect LDH zeta potential. Hence, this work shows that the flow through a column comprising a 2D particle bed can be regulated in a reversible manner by simply alternating the pH of the wash solution, equilibration time, or gate dimensions. Furthermore, we show that, subject to pH treatment, we may open and close the colloidal gate for the transport of large molecules and provide selective transport thereof.

Depletion-Induced Self-Assembly of Colloidal Particles on a Solid Substrate

“…Moreover, regioselective functionalization of colloidal particles was achieved through depletion-induced self-assembly, allowing for the creation of materials with tailored chemical and physical properties . In different types of applications, the preferential exclusion of nanoparticles or polymers from the vicinity of macromolecules in a crowded system generates a depletion zone that leads to an attractive depletion force. − This may lead to so-called depletion flocculation and has been utilized in various fields such as water purification, − virus particle assembly, , and also underlies macromolecular crowding in biological cells. , …”

“… 12 In different types of applications, the preferential exclusion of nanoparticles or polymers from the vicinity of macromolecules in a crowded system generates a depletion zone that leads to an attractive depletion force. 13 − 15 This may lead to so-called depletion flocculation and has been utilized in various fields such as water purification, 16 − 18 virus particle assembly, 19 , 20 and also underlies macromolecular crowding in biological cells. 21 , 22 …”

Diffusion-limited aggregation

“…Once there, the new particle is let loose from infinity and joined to the expanding cluster. The model was investigated both on and off the lattice in multiple dimensions d 2; DLA has garnered a lot of attention throughout the years as a stunning illustration of fractal objects [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].This is a research report on diffusion-limited Aggregation. Diffusion-limited aggregation is a process in which particles of matter stick together (aggregate) as they chaotically move (diffuse) through a medium that provides some sort of resistive (limiting) force.…”

“…"Diffusion" refers to the random movement of the particles that make up the structure before they adhere ("Aggregate") to it. "Diffusion-limited" refers to the fact that the structure grows one particle at a time rather than in chunks of particles because the particles are thought to be in low concentrations, preventing them from coming into touch with one another [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Other instances include the development of coral, the route of lightning, the coalescence of dust or smoke particles, and the development of certain crystals.…”