Degree of flocculation

[tammie123]

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My lecture slide says:
Under flocculation: Compact sediment difficult to re-suspend
Over flocculation: Might be irreversible, high viscosity, product looks unattractive, fast sedimentation
De-flocculation: can be caused by addition of surfactants

What is under flocculation, over flocculation and de-flocculation exactly? And why do those things happen in these circumstances?

 

[Jibby321]

First we should define flocculation in a general sense. That being where colloids (small particles) typically come out of suspension.

De-flocculating- is the act of being able to reverse the flocculation (very difficult) adding polysorbate 80 (tween 80) these are chemical surfactants that can aid in the de flocculation process.

Under flocculation- like you said it is usually reversible but requires a lot of effort through shaking or stirring or whatever other method that may be appropriate. Vortex maybe?

Over flocculation- might as well through it away. Because you won't be able to redisperse the flocculants.

So why does it happen? Well it could happen for a number of reasons. But a pretty common reason is say a bottle of drug X which is a suspension say on the shelf for a long time.

Hopefully this helps. If anything is wrong feel free to correct me. We covered this last semester so I am going off that knowledge.