Fig. 2 Photographs of the
demulsification phenomenon (a ) (the dosage of MIL-100(Fe) and
concentration of model emulsion were 1% (w·w-1) and
1:250 (v·v-1)), microscope photographs of the
demulsified liquid (b ) and model emulsion (c )
To investigate the influence of time, pH and salinity on the
demulsification performance of MIL-100(Fe), the rest demulsification was
carried out with a 0.5% (w·w-1) of MIL-100(Fe) and
1:250 (v·v-1) of model emulsion. As showed inFig. 3a , the DE exceeded 86% of maximum demulsification
capacity within 1 min, and the saturated demulsification time was no
more than 30 min. When the pH was 2.0, the DE was 97%. As increasing
for pH from 4.0 to 10.0, the DE maintained around 90% (Fig.
3b ). Besides, the DE increased from 92% to 98%, following a rise of
the salinity (1 mmol·L-1 ~ 1000
mmol·L-1) (Fig. 3c ). What’s more, a DE of
95% indicated that the demulsification performance of MIL-100(Fe) was
not inhibited by the 10 mmol·L-1 of
Mg2+ solution. Generally, the concentrated electrolyte
could weaken the electrostatic attraction by shrinking the double
electric layer and supramolecular interaction by increasing the
hydration, thus decreasing the demulsification performance of
demulsifier 17. But this was contrary to the results
in this work, which implied that the interaction between MIL-100(Fe) and
emulsion was more powerful than that of the conventional demulsifiers.
Afterwards, the regenerability of MIL-100(Fe) was studied. The DE of the
used MIL-100(Fe) decreased by 14% and 36% after 2th and 3th cycles
(Fig. 3d ). The reason of decrease for the demulsification
performance might be related to the change of wettability for the used
MIL-100(Fe), which was illuminated by the following study.