Chapter 5
samples that were not shaken have loose solids layers. The samples that were
shaken have more compact solids layers.
Sample: 7 8
Adding: NaOH
I. pH: 8.5 8.8
E. pH: 8.0-8.5 8.5
9 10 11
NaOH Na2SiO3
Shaking Shaking Shaking
8.5 8.8 8.8
8.0-8.5 8.5 8.5
Figure 5.4 Photographs of 24 h emulsion with NaOH or Na2SiO3 at different pH
Figs. 5.5 - 5.7 show photomicrographs obtained by sampling from the five
different positions indicated on the right side in Figure 5.4. Sample 7, which is not
shaken, exhibits rigid skins in the rag layer (in Figure 5.5). Sample 8 has similar
results, though the pH was increased. In contrast, all three samples that are
shaken exhibit oil-in-water emulsions at the two highest sampling positions. A few
skins are seen in the lowest sampling position of sample 9, where nothing was
added and pH remained at 8.5 (Figure 5.6). No skins are seen for samples 10,
where pH was raised to 8.8 (in Figure 5.7). Sample 11 has similar results to
Sample 10.
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