Chapter 4
Increasing pH can enhance the dissociation of surface sites and make net surface
charge more negative, hereby kaolinite zeta potential will become more negative.
8.3 8.4 8.5 8.6 8.7
9
PH
Figure 4.27 Kaolinite zeta potential in synthetic brine adding NaOH at different pH
4.3.5.5. Effect of carbonate
Carbonate has two effects on the zeta potential of kaolinite. Adding carbonate
can increase pH and the concentration of НСОз' ion, which can make zeta
potential of kaolinite more negative. Here only the adsorption of НСОз' ion is
considered instead of СОз2' ion, because the concentration of НСОз' ion is much
higher than СОз2' ion in the brine. Carbonate can also precipitate Ca2+ ion, which
can also make zeta potential of kaolinite more negative.
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