The name is absent

Chapter 4

-AOH₂⁺, which can also make zeta potential of kaolinite more negative.

In synthetic brine, positively charged sites -AOH₂⁺ can adsorb citrate ion
CeHsO₇³' (L³') and become negatively charged sites -AOH₂L²'. Here only the
adsorption of L³' ion is considered instead of other ions (HL²' and H₂L') because in
the brine the concentration of L³' ion is much higher than other ions.

-АОИ; +L³' -AOH₂L²

_κ [AOH₂L²-] _      [AOH₂L²-]

^l [Лещадь’) [AOH⅛(L^j)exp(¾
kT

σ₀ = β([AOH₂ ] - [AO^ ] - [B^ ]-2[AOH₂L²^ ])

Figure 4.31 shows zeta potential of kaolinite in synthetic brine adding citrate.
The blue dashed curve shows the fitted zeta potential of kaolinite without Ca/ Mg.
The red solid curve shows the fitted zeta potential of kaolinite with Ca/ Mg.
Adding citrate will not affect the pH of the brine. So the pH of synthetic brine stays
8.3 with different amount of citrate. With the increase of citrate concentration, zeta
potential of kaolinite becomes more negative. At low citrate concentration (3×10'⁴
M), zeta potential change of kaolinite is around 20 mV∕mM. But with the increase
of citrate concentration, the decreasing tendency of zeta potential becomes
saturated. Zeta potential change of kaolinite tends to zero. The equilibrium
constant Kl is the 0.66 m³∕mol.

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