Chapter 3
data for Remu∣ as described in section 3.3.2, using dgv, σ, Dcp and к as fitting
parameters. Based on data fitting, mean diameter dgy and geometric standard
deviation σ are 14 μm and 0.4. Signal attenuation fraction κ0i∣, κemu∣ and κwater are
0.36, 0.02 and 0.62, respectively. Diffusivity of continuous oil phase Dcp is
5.7×10^1° m2∕s.
The time-dependent drop size distributions of different emulsion samples
obtained from diffusion results are shown in Table 3.4.
In sample 4, after 3.2 hours, NMR signal attenuation is smaller than 0.01,
which implies complete separation of the oil and the water. Thus a drop-size
distribution of the emulsion cannot be obtained. Hence only first three results are
listed.
For samples 1 and 3, the mean drop diameter, standard deviation σ, κ0∣∣and
Kemui do not change much with time, which suggests that the emulsions are stable;
the κwater values are very low, which shows that coalescence is very slow in the
absence of demulsifier. In contrast, for samples 2 and 4, κwater increases over time,
which demonstrates that demulsifier PR5 accelerates emulsion coalescence. The
parameter κemu∣ of sample 4 is much smaller than that in of sample 2, which
indicates a lower emulsion content. Sample 2 has much more solids than sample
4; thus, the effect of solids is to make the emulsion more stable.
68