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10
CH1012
CHARGE
Origin of Charge
1) Dissociation of ionisable groups at the
surface of disperse phase particles
eg. -Si-OH ® ( pH>3 )  -SiO- +    H+
2) Adsorption of ions by disperse phase
eg.  Cottrell precipitator    
        uncharged smoke + ions
Electric Double Layer
S
O
L
I
D
- surface charge
- counter ions
- co-ions
Double layer is the surface charge layer and counter ion layer