The name is absent

Chapter 4

more negative with the increase of pH. Table 4.8 shows the calculated parameters
from data fitting. The total amphoteric sites (Λ∕_a∣ + /Vsi) have density 2.33 ×10'⁷
mol∕m² (0.14 site∕nm²). Williams et al. used cation exchange capacity titration
method to get amphoteric charge density ^[27]. The values are from -3 μC∕cm² to
-25 μC∕cm² (site density 3.1 ×10^⁷ mol∕m² - 2.6×W⁶ mol∕m²). The fitted site density
is close to the lower bound of literature value.

Figure 4.18 Zeta potential of kaolinite in 0.05 M NaCI brine at different pH

Figs. 4.19 and 4.20 show the sites fraction of -AOH, -AO^ and -AOH₂⁺ (A
can be Al or Si) in -SiOH and -AIOH sites as the function of bulk pH in 0.05 M
NaCI. As pH increases, the fraction of positively charged sites -AOH₂⁺ will

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