What stabilizes a colloid suspension?
The steric stabilization of colloids involves additives that are added to the fluid medium to inhibit the coagulation of the particle suspension. Dispersants should be stably dispersed in the fluid medium to achieve good dispersion stability of colloidal particles.
What is colloid stabilization?
Polymeric stabilization of Colloids involves polymeric molecules added to the dispersion medium in order to prevent the aggregation of the colloidal particles. Depletion stabilization of colloids involves unanchored (free) polymeric molecules creating repulsive forces between the approaching particles.
How are colloidal system stabilized?
Stabilization. The stability of a colloidal system is defined by particles remaining suspended in solution and depends on the interaction forces between the particles. If this is the case, then the colloidal particles will repel or only weakly attract each other, and the substance will remain a suspension.
What are the characteristics of colloids and suspensions?
Colloids
| Solution | Colloids | Suspensions |
|---|---|---|
| Do not separate on standing | Do not separate on standing | Particles settle out |
| Cannot be separated by filtration | Cannot be separated by filtration | Can be separated by filtration |
| Do not scatter light | Scatter light (Tyndall effect) | May either scatter light or be opaque |
What is stability of suspension?
It is important to understand that suspensions are kinetically stable, but thermodynamically unstable, system. Physical stability is defined as the condition in which the particles remain uniformly distributed throughout the dispersion without any signs of sedimentation.
How do you purify colloids?
Some of the methods of purification of a colloidal solution are stated below:
- Dialysis: The process in which the ions are removed from the solution by the phenomenon of diffusion through a permeable membrane is known as dialysis.
- Electrodialysis:
- Ultrafiltration:
- Electro Decantation:
What is steric stabilization of nanoparticles?
The adsorption of large molecules on the nanoparticle surface that includes surfactant or polymers to prevent aggregation is called steric stabilization. Due to increase of concentration of adsorbed molecules, there is an increase of osmotic repulsive force that enhances the stability of nanostructured particles [52].
Why are the colloids quite stable?
Stability: Colloids are relatively stable in nature. The particles of the dispersed phase are in a state of continuous motion and remain suspended in the solution. This is because the suspended particles are so tiny that they are not visible by the naked eye.
What causes stability of colloids?
The stability of the colloidal sols is due to the presence of charge on colloidal particles. The similarly charged particles mutually rapel. Apart from these sol particles gat solvated and participate in Brownian motion.
What are suspensions What are the main characteristics of suspensions?
General Characteristics and Properties of Suspension Suspensions are a heterogeneous mixture of two or more substances. Particles of the solute do not dissolve in the solvent rather they remain suspended in bulk throughout. The size of particles of suspension is large enough to be visible from naked eyes.
What are three characteristics of suspensions?
Properties of Suspension
- A suspension is a heterogeneous mixture.
- The size of solute particles in a suspension is quite large.
- The particles of a suspension can be seen easily.
- The particles of a suspension do not pass through a filter paper.
- The suspension is unstable.
How suspension are stabilized?
Stabilizing a suspension preventing coagulation through inter-particle repulsion. slowing down sedimentation by increasing the viscosity of the continuous phase.
How are two mechanisms of colloidal stability take place?
According to the kind of the repulsion force two mechanisms of the colloidal stability take place: Electrostatic stabilization of colloids Polymeric stabilization of colloids Electrostatic stabilization of colloids
How is coagulation of colloidal suspensions effected?
Coagulation, or the destruction of colloidal stability, may be effected in four major ways: (i) boiling; (ii) freezing; (iii) mutual flocculation by addition of a colloid of opposite charge; and (iv) the addition of electrolytes. Of these only the latter is of major significance in water and wastewater engineering practice.
How does the electric double layer help to stabilize colloids?
Electric Double Layer is the phenomenon playing a fundamental role in the mechanism of the electrostatic stabilization of colloids. Colloidal particles gain negative electric charge when negatively charged ions of the dispersion mediumare adsorbed on the particles surface.
How are nanoparticles stabilized in a concentrated suspension?
The formation of a dispersant layer (adlayer) of appropriate thickness is crucial for the stabilization of suspensions containing high nanoparticle concentrations. Thick adlayers result in an excessive excluded volume around the particles, whereas thin adlayers lead to particle agglomeration.