Iso-electric Point
The Iso-electric point is one such property. The iso-electric point is the pH value at which the zeta potential is approximately zero. At a pH near the iso-electric point (± 2 pH units), colloids are usually unstable; the particles tend to coagulate or flocculate. Such titrations use acids or bases as titration reagents. Tables of iso-electric points for different materials are available. The attached figure illustrates results of such titrations for concentrated dispersions of alumina (4% v/v) and rutile (7% v/v). It is seen that iso-electric point of alumina is around pH 9.3, whereas for rutile it is around pH 4. Alumina is unstable in the pH range from 7 to 11. Rutile is unstable in the pH range from 2 to 6.
Read more about this topic: Zeta Potential Titration
Famous quotes containing the word point:
“Here I swear, and as I break my oath may ... eternity blast me, here I swear that never will I forgive Christianity! It is the only point on which I allow myself to encourage revenge.... Oh, how I wish I were the Antichrist, that it were mine to crush the Demon; to hurl him to his native Hell never to rise againI expect to gratify some of this insatiable feeling in Poetry.”
—Percy Bysshe Shelley (17921822)