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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: me on March 26, 2008, 05:25:53 AM

Title: coagulation and floculation
Post by: me on March 26, 2008, 05:25:53 AM

  I would like to know the difference between coagulation and floculation of a colloid.
 I've tried to search in the internet but I can't find a satisfactory answer.

                                                                                           Thank you! :D

Title: Re: coagulation and floculation
Post by: Arkcon on March 26, 2008, 06:39:25 AM

As I understand it, flocculation is jargon for coagulation by an added agent.  That's always how I used the term.  Did a Google search reveal something different?

Title: Re: coagulation and floculation
Post by: Yggdrasil on March 26, 2008, 10:28:45 AM

Flocculation is the reversible aggregation of particles in solution whereas coagulation is the irreversible aggregation of particles in solution. 

Flocculation occurs when your interaction potential has a local minimum at a fixed (nonzero) radius, meaning the particles become stably bound to eachother, but if you increase the repulsive forces between particles (e.g. by lowering salt concentration), you can eliminate this local minimum and get a colloidal solution again.

Coagulation, however, occurs when the is no longer an energetic barrier to aggregation (i.e. attraction dominates repulsion at all distances) and all particles want to move toward the global minimum of the potential at r=0.

Title: Re: coagulation and floculation
Post by: Arkcon on March 26, 2008, 11:38:14 AM

Ah ... a much better explanation Yggdrasil:, have one on me.  Like it matters to you at this point.