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The composition of the suspension can be evenly distributed by mechanical ways, such as shaking the mixture. However, once the mixture stops oscillating, the solid particles in the suspension will be eventually settled out.
- Suspension Definition: What is a Suspension ?
- What Characterizes a Suspension ?
- Influencing Factors of Suspension Stability
- Examples of Suspensions
Suspension Definition: What is a Suspension ?
Suspension is a heterogeneous fluid containing solid particles that can be settled. The solid particles cannot be sunk quickly due to Brownian motion, and the mixture of the dispersed solid phase and the liquid is called a suspension.
What Characterizes a Suspension?
The particle size of the solid particles in the suspension is greater than 100nm, larger than that of the colloid. The particles in the suspension are actually completely suspended in the liquid. If the mixture stops oscillating, the particles will be eventually settled out.
All particles in the suspension, regardless of particle size, are subject to the disorderly collision of the thermal motion of the liquid molecules to produce Brownian displacement. The Brownian displacement velocity of the particles increases with the decrease of the particle mass. On the other hand, all suspended particles are affected by gravity, but the gravity settlement displacement decreases as the particle size decreases. Therefore, the combined action of diffusion displacement and settlement displacement produces the polydispersity of suspension.
To accelerate the process of sedimentation in a suspension, centrifuges can be used，by centrifugal force to separate the solid particles from the liquid.
Influencing Factors of Suspension Stability
The stability of the suspension refers to the property that the suspension maintains its own density for a certain period of time. Suspension stability is mainly affected by the following factors:
The size, shape and viscosity of the solid particles in the suspension will affect the stability of the suspension. Generally, the finer the particle size of the solid in the suspension, the more irregular the shape, and the better the stability. For the same suspension, the greater the viscosity, the better the stability; conversely, the smaller the viscosity, the worse the stability.
Examples of Suspensions
- Slurry of sand in seawater
- Orange juice
- Wheat beer
- Concrete or mortar
- Drilling mud