Question

Explain the effect of (i) zeta potential (ii) Hamaker constant and (iii) molar salt concentration on the colloid stability.

Answer 1

Colloidal solution is contains with microsolid substace disperse in the other liquid substance. It also called colloidal suspension.

Due to two other phases it need some stability testing such as-

I- Zeta potential- the potential difference existing between the surface of a solid particle which is immersed in a conducting liquid (e.g. polar solvent or water) and the bulk of the liquid. It must be in limit to found a good stability of colloidal solution.

Zeta potential [mV] Stability behavior of the colloid

from 0 to ±5, Rapid coagulation or flocculation

from ±10 to ±30 Incipient instability

from ±30 to ±40 Moderate stability

from ±40 to ±60 Good stability

more than ±61 Excellent stability

ii Hamaker constant-The Hamaker constant A can be defined for a Van der Waals (VdW) body–body interaction. The force between the particles or bonds make the solution stable.

III molar salt concentration - it is also a most important parameter for colloidal solution. Equilibrium must be maintain in molar concentration. More molar concentration may lead to Aggregragation and very low may lead to DEFFLUCULATIion.