2.4 Demulsification study
Firstly, 40 ml of oleic acid was added into 200 ml of ultrapure water
contained 0.2 g of SDS, stirring by the homogenizer at a speed of 3800
rpm·min-1, to prepare the model emulsion. The model
emulsion was used after diluting by ultrapure water in the next
investigation. The concentration of model emulsion was expressed with a
volume ratio (v·v-1) of oleic acid in water.
Initially, demulsification performance was investigated at different
conditions of dosage, concentration, time, pH and salinity using the
as-prepared material. The regenerability was studied following washing
used material with ethanol and petroleum ether. Typically, 0.10 g of the
as-prepared material was suspended in 19.6 ml ultrapure water, then 0.4
ml of the model emulsion was added into the as-prepared material
suspension. After that, the suspension contained as-prepared material
and model emulsion was silence following shock drastic. And the cycle of
shock-silence did several times in 30 min. Subsequently, the suspension
was filtrated. The filter liquor was extracted by petroleum ether. The
absorbance of extracted liquor was measured at 268 nm by a UV-vis
spectrophotometer (Shimadzu, UV-2600). The demulsification efficiency
(DE) was calculated according to the Eq. 1 :
\(DE=(A_{0}-A_{1})/A_{0}\times 100\%\) (Eq. 1 )
Where, DE (%) was the demulsification efficiency for the model emulsion
using the as-prepared material, A 0 andA 1 were absorbances of extract liquors before and
after demulsification.
To exhibit the demulsification process, the demulsification phenomenon
was recorded by an inverted microscope (AMG EVOSFL, Amercian). The
interaction between as-prepared material and model emulsion was reveal
by attenuated total reflection infrared spectroscopy (ATR-IR, Nicolet
iS5,Thermo Fisher Scientific), X-ray photoelectron spectroscopy (XPS,
ES CALAB 250Xi, Thermo Fisher Scientific) and Zeta potential (Marlven
Nano-ZS, England). Additionally, the components of SDS solution after
interacting with as-prepared material were measured by ion chromatogram
(IC) and liquid chromatogram-mass spectroscopy (LC-MS).