Colloidal Particles and Colloidal Suspensions

Soil Colloids ◽  
2016 ◽  
pp. 36-55 ◽  
Keyword(s):  
Colloidal Particles ◽  
Colloidal Suspensions

Aggregation of binary colloidal suspensions on attractive walls

2016 ◽  
Vol 18 (4) ◽  
pp. 3073-3079 ◽  
Author(s):  
Aleena Laganapan ◽  
Davide Bochicchio ◽  
Marguerite Bienia ◽  
Arnaud Videcoq ◽  
Riccardo Ferrando
Keyword(s):  
Solid Surface ◽  
Colloidal Particles ◽  
Biological Systems ◽  
Colloidal Suspensions ◽  
Fundamental Importance

The adsorption of colloidal particles from a suspension on a solid surface is of fundamental importance to many physical and biological systems.

scholarly journals Directional freezing of binary colloidal suspensions: a model for size fractionation of graphene oxide

Soft Matter ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 243-251 ◽  
Author(s):  
Xin Xu ◽  
Luofu Liu ◽  
Hongya Geng ◽  
Jianjun Wang ◽  
Jiajia Zhou ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Theoretical Model ◽  
Colloidal Particles ◽  
Colloidal Suspensions ◽  
Size Fractionation ◽  
Preferential Adsorption ◽  
Directional Freezing ◽  
Ice Phase

A theoretical model of a binary colloid suspension was developed by incorporating both the moving freezing boundary and the preferential adsorption of colloidal particles to the ice phase.

Liquid Crystal Behavior of V2O5·nH2O Gels

1998 ◽  
Vol 547 ◽  
Author(s):  
J. Livage ◽  
P. Davidson ◽  
X. Commeinhes ◽  
O. Pelletier
Keyword(s):  
Liquid Crystal ◽  
Vanadium Pentoxide ◽  
Colloidal Particles ◽  
Organic Molecules ◽  
Polarized Light ◽  
Colloidal Suspensions ◽  
Acid Dissociation ◽  
Polymeric Particles ◽  
Nematic Phases ◽  
Electrostatic Repulsions

AbstractMost liquid crystals are made of organic molecules, very few of them are based on mineral compounds. Vanadium pentoxide gels and sols have been shown to give mesophases. They are made of ribbon-like polymeric particles of vanadium pentoxide dispersed in water. Ansitropic xerogel layers are formed when these gels are deposited and dried onto flat substrates. Dehydration is reversible and fluid phases are again obtained via a swelling process when water is added to the xerogel.When observed by polarized light microscopy, colloidal suspensions of V2O5 ribbons display defects typical of lyotropic nematic phases. Dilute nematic suspensions can even be oriented by applying a magnetic field of about 0.5 Tesla. Such a liquid crystal behavior is mainly due to the highly anisotropic shape of vanadium oxide colloidal particles. Acid dissociation at the oxide/water interface gives rise to surface electrical charges and electrostatic repulsions should also be responsible for the stabilization of the nematic phase.

scholarly journals THE ELECTRICAL CONDUCTANCE OF SUSPENSIONS OF ELLIPSOIDS AND ITS RELATION TO THE STUDY OF AVIAN ERYTHROCYTES

1940 ◽  
Vol 23 (6) ◽  
pp. 753-771 ◽  
Author(s):  
Sidney Velick ◽  
Manuel Gorin
Keyword(s):  
Electrical Resistance ◽  
Colloidal Particles ◽  
Electrical Conductance ◽  
Colloidal Suspensions ◽  
Optical Methods ◽  
Flow Cells ◽  
Flow Method ◽  
Avian Erythrocytes

1. The theory of electrical conductance of colloidal suspensions has been extended to cover the case of ellipsoids with three axes different. 2. The results have been applied to suspensions of ellipsoidal erythrocytes of birds. 3. It has been shown that fluctuations in electrical resistance of suspensions of erythrocytes after stirring are due to streaming orientation of the cells. 4. The theory has been extended to cover four cases of orientation and tested experimentally in specially designed flow cells by electrical and optical methods. 5. Application of the flow method to the study of the shape of colloidal particles is discussed.

Dielectrophoretic Mixing With Novel Electrode Geometry

2009 ◽  
Author(s):  
G. Naga Siva Kumar ◽  
Sushanta K. Mitra ◽  
Subir Bhattacharjee
Keyword(s):  
Electric Field ◽  
Cell Activation ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Computational Domain ◽  
Element Analysis

Electrokinetic mixing of analytes at micro-scale is important in several biochemical applications like cell activation, DNA hybridization, protein folding, immunoassays and enzyme reactions. This paper deals with the modeling and numerical simulation of micromixing of two different types of colloidal suspensions based on principle of dielectrophoresis (DEP). A mathematical model is developed based on Laplace, Navier-Stokes, and convection-diffusion-migration equations to calculate electric field, velocity, and concentration distributions, respectively. Mixing of two colloidal suspensions is simulated in a three-dimensional computational domain using finite element analysis considering dielectrophoretic, gravitational and convective (advective)–diffusive forces. Phase shifted AC signal is applied to the alternating electrodes for achieving the mixing of two different colloidal suspensions. The results indicate that the electric field and DEP forces are maximum at the edges of the electrodes and become minimum elsewhere. As compared to curved edges, straight edges of electrodes have lower electric field and DEP forces. The results also indicate that DEP force decays exponentially along the height of the channel. The effect of DEP forces on the concentration profile is studied. It is observed that, the concentration of colloidal particles at the electrodes edges is very less compared to elsewhere. Mixing of two colloidal suspensions due to diffusion is observed at the interface of the two suspensions. The improvement in mixing after applying the repulsive DEP forces on the colloidal suspension is observed. Most of the mixing takes place across the slant edges of the triangular electrodes. The effect of electrode pairs and the mixing length on degree of mixing efficiency are also observed.

MODELING OF THE SURFACE TENSION OF COLLOIDAL SUSPENSIONS

2016 ◽  
Vol 24 (04) ◽  
pp. 1750050 ◽  
Author(s):  
ROGHAYEH HADIDIMASOULEH ◽  
MAZIAR SAHBA YAGHMAEE ◽  
REZA RIAHIFAR ◽  
BABAK RAISSI
Keyword(s):  
Surface Tension ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Colloidal Suspensions ◽  
Thermodynamic Relation ◽  
Fundamental Properties ◽  
Bubble Pressure ◽  
Air Water Interface ◽  
Numerous Experimental Data ◽  
Modified Equation

Surface tension is one of the fundamental properties of the colloids, which can be altered by concentration and size of colloidal particles. In the current work, modeling of the surface tension of suspension as it would be analyzed by maximum bubble pressure method has been performed. A new modified equation to correlate the surface tension with the bubble pressure is derived by applying fundamental thermodynamic relation considering the presence of particles in suspension and curvature of the interface between the particles and bubbles inside liquid. Moreover, the change of particles concentration in air–water interface due to capillary force is also considered. The predicted surface tension using the developed model has been verified by numerous experimental data with deviation less than 5% in most of cases. It was found that the calculated surface tension is altered by contact angle and particle radius as well as particle concentration. The obtained model may have potential application to predict the surface tension of colloidal suspension.

Phases of Thin Colloidal Layers

MRS Bulletin ◽  
1998 ◽  
Vol 23 (10) ◽  
pp. 33-38 ◽  
Author(s):  
Cherry Murray
Keyword(s):  
Self Assembly ◽  
Optical Materials ◽  
Colloidal Particles ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Dielectric Behavior ◽  
Thin Layers ◽  
Photonic Bandgap Materials ◽  
Colloidal Spheres ◽  
Assembly Technique

Colloids have long been used in applications such as paints, coatings, foods, and many manufacturing processes. Recently, synthetic crystalline arrays of colloidal particles have been used as novel optical materials such as diffractive filters, mimicking the optical properties of opals—natural colloidal crystals made from silica spheres. Colloidal assembly has been proposed to manufacture photonic bandgap materials that can be tailored and that could have many uses in optical devices. The advantages of using colloids to do the self-assembly of novel materials are the relative ease with which monodisperse spheres comparable in size to the wavelength of light can be manufactured and also the demonstrated ease by which some suspensions of monodisperse colloidal spheres crystallize when placed under favorable conditions. Before we can use colloidal crystallization as a controlled self-assembly technique for making novel optical materials, we need (1) to create a means of manufacturing large quantities of monodisperse particles of the desired dielectric behavior, (2) to understand the phase diagram and nucleation phenomena of colloidal suspensions, and (3) to find an easy means to fix the particles in place once they selforganize. In this article, I focus on the second point just mentioned, I give an overview of the phases and some of the complex phenomena encountered in three-dimensional (3D) suspensions and in thin layers of monodisperse colloidal spheres between smooth walls, and I then briefly mention the greater complexity encountered in bidisperse systems. The first and third points will be dealt with elsewhere in this issue.

scholarly journals Lyotropic Liquid Crystals from Colloidal Suspensions of Graphene Oxide

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 455 ◽  
Author(s):  
Adam P. Draude ◽  
Ingo Dierking
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Colloidal Particles ◽  
Colloidal Suspensions ◽  
Lyotropic Liquid Crystals ◽  
Nanoscience And Nanotechnology ◽  
And Behavior

Lyotropic liquid crystals from colloidal particles have been known for more than a century, but have attracted a revived interest over the last few years. This is due to the developments in nanoscience and nanotechnology, where the liquid crystal order can be exploited to orient and reorient the anisotropic colloids, thus enabling, increasing and switching the preferential properties of the nanoparticles. In particular, carbon-based colloids like carbon nanotubes and graphene/graphene–oxide have increasingly been studied with respect to their lyotropic liquid crystalline properties over the recent years. We critically review aspects of lyotropic graphene oxide liquid crystal with respect to properties and behavior which seem to be generally established, but also discuss those effects that are largely unfamiliar so far, or as of yet of controversial experimental or theoretical outcome.

scholarly journals On electrical effects due to sound waves in colloidal suspensions

1951 ◽  
Vol 207 (1090) ◽  
pp. 329-342 ◽  
Keyword(s):  
Double Layer ◽  
Colloidal Particles ◽  
Wave Train ◽  
Wave Length ◽  
Colloidal Suspensions ◽  
Exact Expression ◽  
Particle Radius ◽  
Potential Difference ◽  
Sound Waves ◽  
Leading Term

In this paper, the electrical effects accompanying the propagation of sound waves through a suspension of spherical colloidal particles in an electrolyte are examined. It is shown that, for charged colloidal particles, differences of potential arise between different points in the wave train. A general method is given for obtaining the amplitude of the potential difference in the case when the thickness of the double-layer surrounding the particles is small compared with the particle radius, as a power series in the zeta-potential and the leading term in this series is evaluated, so that the results will be adequate for zeta-potentials which are not too large. An exact expression is obtained for the case when the thickness of the double-layer is very much greater than the particle radius but still much less than the mean separation. An attempt is also made to estimate the effect for intermediate values of the double-layer thickness. The amplitude of the potential difference decreases with increasing concentration of electrolyte and, when measured between points a half-wave-length apart, is substantially independent of the frequency of the sound waves, except at very high frequencies. The results are compared with the experimental data.

Interactions and Dynamics in Charge-Stabilized Colloids

MRS Bulletin ◽  
1998 ◽  
Vol 23 (10) ◽  
pp. 24-31 ◽  
Author(s):  
John C. Crocker ◽  
David G. Grier
Keyword(s):  
Self Assembly ◽  
Colloidal Particles ◽  
Protein Crystallization ◽  
Colloidal Suspensions ◽  
Industrial Processes ◽  
Fluid Medium ◽  
Nano Structures ◽  
Naturally Occurring ◽  
Electrostatic Stabilization ◽  
Natural Tendency

Perhaps the most remarkable observation one can make about colloidal suspensions is that they exist at all. Particles dispersed in a fluid medium have a natural tendency to aggregate under the influence of van der Waals attraction. Yet the fortunes of a great many natural and industrial processes require colloidal particles to remain dispersed or at least to aggregate at a controlled rate. The existence of colloidal suspensions as varied as milk, inks, and metallic sols attests to the efficacy of a variety of stabilizing mechanisms. As early as 1809, Russel realized that many naturally occurring colloidal particles are charged. By the end of the century, Schultz and Hardy demonstrated that the resulting electro-static repulsions were strong enough to stabilize their suspensions against flocculating. This mechanism—arguably the best understood—continues to yield new surprises despite more than a century of analysis. The most recent burst of activity has been driven by the development of new and quite general techniques for measuring colloidal and macromolecular interactions. Its counterintuitive result—that like-charged particles some-times attract each other—may have ramifications in areas as diverse as protein crystallization, self-assembly of nano-structures, and the stabilization of industrial suspensions. This article touches briefly on the well-established theory of electrostatic stabilization in colloidal suspensions. The emphasis here is on the approximations that have provided the community with an analytical theory at the expense of overlooking recently discovered effects.

Sign in / Sign up

Export Citation Format

Share Document