Chapter 4
Figure 4.20 Alumina sites fraction in kaolinite at different bulk pH in 0.05 M NaCI
In section 4.3.2, amphoteric silica and alumina sites on kaolinite surface is
assumed. Based on the results of Figs. 4.19 and 4.20, above pH 8, silica sites are
negatively charged, alumina sites are dependent of pH. To verify the assumption,
zeta potentials of alumina in 0.05 M NaCI brine at different pH are measured.
Equations for charge density and site dissociation equilibrium of alumina are:
σ0 =e([AlΘH2]-[A10^]) [4.28]
[AlOH]αd(H +)exp(-⅛
[A10H2+] =-----------------[4.29]
ʌʌɪ+
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