The name is absent

Chapter 4

Figure 4.22 shows the sites fraction of -AIOH, -AIO' and -AIOH₂+ sites as
the function of bulk pH in 0.05 M NaCI. As pH increases, the fraction of positively
charged sites -AI0H₂⁺ will decrease; the fraction of negatively charged sites
-AIO' will increase. This is similar to kaolinite in Figure 4.20.

4.3.5.2. Adsorption effect of anions SO4²' and HCO3'

Synthetic brine contains anions SO₄²' and НСОз'. Zeta potentials of kaolinite
in 0.05 M NaCI brine adding Na₂SO4 at pH 6.5 were measured to study the effect
of sulfate. In 0.05 M NaCI brine at pH 6.5, positively charged sites -AOH₂⁺ (A can
be Al or Si) can adsorb Sθ4²' ion and become negatively charged sites
-AOH₂SO₄'.

-AOH₂ +SO₄^   -AOH₂SO₄

_κ __ [AOH₂SO₄] _ [AOH₂SO₄]
^so∙ [A0H⅛,(S<⅛) [AOH⅛∕SO∏exp(⅛H

σ, = e([ AOH₂ ] - [ AO’ ] - [B HAOH₂SO₄ ])

Here Ks04 is the adsorption equilibrium constant.

Using the similar method discussed in section 4.3.5.1, based on Eqs [4.6],
[4.32] and [4.33], adsorption equilibrium constant can be calculated from
experiment data. For the adsorption of other ions, similar method can be used to
evaluate adsorption equilibrium constant. Figure 4.23 shows zeta potential of

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