Chapter 5
This experiment shows that the oil-in-water emulsion can be broken at a low
pH level, i.e. 5.0 or lower. Study of interfacial properties of emulsified bitumen
droplets also shows that bitumen drops are unstable at low pH t9j. When the pH is
low enough, all the soap will form naphthenic acid. The system will prefer to form
a water-in-oil emulsion. But because the oil layer contains demulsifier PR5,
water-in-oil emulsions are not stable in the absence of clay solids. Thus clean oil
and bulk water layers can be obtained.
5.6. Three-step separation Ofdiluted bitumen emulsion
5.6.1. Methods
Afterfinding the optimal separation conditions in each step (section 5.3 - 5.5),
the entire three-step procedure was performed. 60 ml water-in-oil diluted bitumen
emulsion was prepared with 50 vol.% diluted bitumen and 50 vol.% synthetic
brine with 1x10'4 M silicate at 50 0C, as described in section 5.2. 200 ppm PR5
was added to 30 ml emulsion sample immediately after preparation. The clean oil
Iayerwas removed 24 h after emulsion preparation. 2x10^4 M NaOH was added to
aqueous phase to increase the initial pH to 8.8 with shaking. The emulsion layer
and solids layer were separated 24 hours later. Atotal of 0.15ml 1.0 M HCI was
added to the emulsion Iayerto Iowerthe equilibrium pH to 5.0. Photographs of the
separation were taken 24 hours later.
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