Basic theory of suspensions and flocculation

The DLVO Theory [ 1 ] was the first theory to explain the balance of forces that lead to colloid stability or instability. The range of the electrostatic repulsive forces described above is relatively large, of the order of 300 nm. However, in any suspension system, other forces operate, such as van der Waals forces of attraction and these are present at the solid—liquid interface. These forces are relatively strong but they are also short ranged, in the order of 5-10 nm. 

A result of these opposing forces is that, as particles approach each other, a maximum in the potential energy curve is observed [2]. 

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