Out of which layers consists the double layer of a particle in suspension?
adsorbed layer
diffuse layer
How is the width of the double layer called?
debye length
How does the electrical potential behave in suspension with distance
x=way from surface
kappa=debye length
What are the effects of different solvents on the debye length?
N=number of moles
epsilon=dielectric constant
What is the physical meaning of the Zeta potential?
The potential at the edge of the double layer of the particle, when the particle is in motion by an electric field. (=where ions are sheared off by motion <=> shear plane)
better measureable than debye length
What is the meaning of the isoelectric point (IEP)
If the PH-value is above this point the particle will be negatively charged.
If the PH-value is below this point the particle will be positively charged.
How does the PH-value change the charge of the particle?
the adherent neutral OH groups are charged positively by H+ or negatively by OH-
What is the meaning of PZC?
point of zero charge
What is the PZC related to?
the higher the charge/radius quotient the lower the PZC
What is the attracting and the repulsing force in a suspension?
Attraction: Van der Waals force
Repulsion: interaction between double electric layers
What is the use of deflocculants?
to increase the spread in a solution
Why are ceramic solutions floculating?
Because of two minima in the repulsive barrier (combination of repellant and attracting force)
Which factors influence flocculation?
psi=surface potential
R=particle radius
What are the forms of deflocculation?
electrostatic defloculation
steric stabilization
electrosteric stabilization
Name two anorganic and two organic defloculating agents.
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