The name is absent

Chapter 4

prepared in the brine with different additives. Branson Sonic Probe 450 was used
for the sonication of the mixture (probe tip was placed about 1/2" into the solution,
sonication rate at setting 4 for 1 minute). The mixture was left overnight. Before
measurement the mixture was shaken and settled for 30 minutes to allow the
sedimentation of larger particles and get stable suspension. Beckman Coulter
Delsa 440 Doppler electrophoretic light scattering analyzer was used to measure
zeta potential of kaolinite or alumina in the brine.

Standard mobility solution (conductivity 1000 mS∕cm, mobility -4 μmcm∕V∙s,
Beckman Coulter, PN# 8301351) was measured at different position levels for
calibration. The measured value at upper and lower stationary levels (84% and
16% of the depth) reflect the true mobility of the solution ^[17]. Kaolinite or alumina
sample was measured at lower and upper stationary levels for three times
respectively. The average value of zeta potentials of lower and upper stationary
levels was chosen as the zeta potential value of the sample. Appendix B shows
detailed procedure of zeta potential measurement.

4.3.4. Effects of additives on kaolinite zeta potential in synthetic brine

Kaolinite zeta potentials in synthetic brine with different additives were
measured, as shown in Figure 4.16, to characterize wettability change of kaolinite.

For all the samples, zeta potentials are more negative without Ca/ Mg ions

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