U.S. patent number 10,385,254 [Application Number 16/042,723] was granted by the patent office on 2019-08-20 for ecofriendly emulsifier synthesis from esterified waste vegetable oil for wellbore drilling fluids.
This patent grant is currently assigned to Saudi Arabian Oil Company. The grantee listed for this patent is Saudi Arabian Oil Company. Invention is credited to Md Amanullah, Jothibasu Ramasamy.
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United States Patent |
10,385,254 |
Ramasamy , et al. |
August 20, 2019 |
Ecofriendly emulsifier synthesis from esterified waste vegetable
oil for wellbore drilling fluids
Abstract
Ecofriendly emulsifier synthesis from esterified waste vegetable
oil for wellbore drilling fluids is described. A raw material waste
vegetable oil is esterified to produce a methyl ester of the raw
material waste vegetable oil. A caustic soda solution is added to
the methyl ester resulting in a mixture. The mixture is thermally
treated. A pH of the mixture is adjusted resulting in formation of
an aqueous phase and a non-aqueous phase. The aqueous phase is
separated from the non-aqueous phase.
Inventors: |
Ramasamy; Jothibasu (Dammam,
SA), Amanullah; Md (Dhahran, SA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Saudi Arabian Oil Company |
Dhahran |
N/A |
SA |
|
|
Assignee: |
Saudi Arabian Oil Company
(Dhahran, SA)
|
Family
ID: |
65040852 |
Appl.
No.: |
16/042,723 |
Filed: |
July 23, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190031940 A1 |
Jan 31, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62537572 |
Jul 27, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K
8/035 (20130101); B01F 3/0811 (20130101); C11C
3/04 (20130101); C09K 8/36 (20130101); C09K
2208/06 (20130101); B01F 2003/083 (20130101) |
Current International
Class: |
B01F
3/08 (20060101); C11C 3/04 (20060101); C09K
8/36 (20060101); C09K 8/035 (20060101) |
Field of
Search: |
;554/161 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1318427 |
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Oct 2001 |
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CN |
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102286273 |
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Dec 2011 |
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CN |
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2336291 |
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Oct 2008 |
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RU |
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2652378 |
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Nov 2017 |
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RU |
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2062920 |
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Aug 2002 |
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WO |
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2013078374 |
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May 2013 |
|
WO |
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WO-2013078374 |
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May 2013 |
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WO |
|
Other References
International Search Report issued in International Application No.
PCT/US2018/043675 dated Oct. 9, 2018, 12 pages. cited by
applicant.
|
Primary Examiner: Carr; Deborah D
Attorney, Agent or Firm: Fish & Richardson P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of priority to U.S. Provisional
Patent Application Ser. No. 62/537,572, filed Jul. 27, 2017 and
entitled "ECOFRIENDLY EMULSIFIER SYNTHESIS FROM ESTERIFIED WASTE
VEGETABLE OIL FOR WELLBORE DRILLING FLUIDS," the contents of which
are hereby incorporated by reference.
Claims
The invention claimed is:
1. A method of cleaving an ester group of a methyl ester of waste
vegetable oil to produce an emulsifier of the waste vegetable oil,
the method comprising: adding a caustic soda solution to the methyl
ester resulting in a mixture; thermally treating the mixture;
adjusting a pH of the mixture resulting in formation of an aqueous
phase and a non-aqueous phase; and separating the aqueous phase
from the non-aqueous phase.
2. The method of claim 1, wherein the caustic soda solution
comprises an alkoxide dissolved in a solvent.
3. The method of claim 1, wherein the caustic soda solution
comprises sodium hydroxide.
4. The method of claim 2, wherein the solvent comprises water.
5. The method of claim 1, further comprising stirring the mixture
during thermally treating the mixture.
6. The method of claim 1, wherein the mixture is heated to a
temperature greater than room temperature.
7. The method of claim 6, wherein the temperature is substantially
60.degree. C.
8. The method of claim 1, wherein adjusting the pH of the mixture
comprises adding an acid.
9. The method of claim 8, wherein the acid is substantially 31%
hydrochloric acid.
10. The method of claim 1, wherein the adjusted pH of the mixture
is substantially between 4 and 5.
11. A method comprising: cleaving an ester group of a methyl ester
of waste vegetable oil to produce an emulsifier of the waste
vegetable oil; adding a caustic soda solution to the methyl ester
resulting in a mixture; thermally treating the mixture at
substantially 60.degree. C.; adjusting a pH of the mixture by
adding an acid; forming of an aqueous phase and a non-aqueous phase
in response to adding the acid; and separating the aqueous phase
from the non-aqueous phase.
Description
TECHNICAL FIELD
This disclosure relates to the synthesis of an ecofriendly
emulsifier for wellbore drilling systems from esterified waste
vegetable oil.
BACKGROUND
Wellbore drilling operations use wellbore drilling fluids for
multiple purposes including, for example, to cool the drill bit, or
to transport wellbore cuttings from inside the wellbore to the
surface. Drilling fluids are also used to reduce friction between
the drill string and the casing, the wellbore wall, or both, by
acting as a lubricating medium for the drill string while drilling
the wellbore. Drilling fluids can be divided into categories, for
example, oil-based drilling fluids or water-based drilling fluids.
Sometimes, additives are added into either or both categories of
drilling fluids to enhance the properties of the drilling
fluids.
SUMMARY
This disclosure describes ecofriendly emulsifier synthesis from
esterified waste vegetable oil for wellbore drilling fluids, for
example, oil-based wellbore drilling fluids.
Certain aspects of the subject matter described here can be
implemented as a method. A raw material waste vegetable oil is
esterified to produce a methyl ester of the raw material waste
vegetable oil. A caustic soda solution is added to the methyl ester
resulting in a mixture. The mixture is thermally treated. A pH of
the mixture is adjusted resulting in formation of an aqueous phase
and a non-aqueous phase. The aqueous phase is separated from the
non-aqueous phase.
This, and other aspects, can include one or more of the following
features. The caustic soda solution can include an alkoxide
dissolved in a solvent. The alkoxide can include sodium hydroxide.
The solvent can include water. The mixture can be stirred during
thermally treating the mixture. The mixture can be heated to a
temperature greater than room temperature. The temperature can be
substantially 60.degree. C. Acid can be added to adjust the pH of
the mixture. The acid can be substantially 31% hydrochloric acid by
volume. The adjusted pH of the mixture can be substantially between
4 and 5.
Certain aspects of the subject matter described here can be
implemented as a method. An ester group of a methyl ester of waste
vegetable oil is cleaved to produce an emulsifier of the waste
vegetable oil. A caustic soda solution is added to the methyl ester
resulting in a mixture. The mixture is thermally treated at
substantially 60.degree. C. A pH of the mixture is adjusted by
adding an acid. An aqueous phase and a non-aqueous phase are formed
in response to adding the acid. The aqueous phase is separated from
the non-aqueous phase.
The details of one or more implementations of the subject matter
described in this specification are set forth in the accompanying
drawings and description. Other features, aspects, and advantages
of the subject matter will become apparent from the description,
the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a drilling fluid circulation
system.
FIG. 2 is a schematic diagram showing drilling fluid flowing
through a drill string and an annulus between the drill string and
a wellbore.
FIG. 3 is a flowchart of an example process of producing emulsifier
using esterified waste vegetable oil.
FIG. 4 is a flowchart of an example process of producing esterified
waste vegetable oil.
Like reference numbers and designations in the various drawings
indicate like elements.
DETAILED DESCRIPTION
Water-based drilling fluids may not be a viable drilling fluid
option for certain high pressure and high temperature (HPHT)
sections of a borehole. For such HPHT sections, invert emulsion oil
based mud (OBM) can be used as drilling fluids. Shale formations
are sensitive to water and can swell, disintegrate, and collapse
upon contact with water. For this reason, OBMs are also be used as
drilling fluids when drilling very reactive shale section to
stabilize the shale. Certain oil-based drilling fluids, such as the
invert emulsion OBM or 100% oil-based drilling fluids, include
emulsifiers to create a stable emulsion of water in oil.
Emulsifiers are a type of surfactants that have a hydrophilic head
group and a hydrophobic tail (for example, a long chain hydrophobic
tail). Emulsifiers can reduce interfacial tension between water and
oil phases to achieve stability of the drilling fluid. Tall oil
fatty acids (TOFA) are an example class of emulsifiers that are
used in oil-based drilling fluids, for example, invert emulsion
OBMs.
This disclosure describes an ecofriendly emulsifier that can be
used in oil-based drilling fluids, such as invert emulsion OBMs.
The ecofriendly emulsifier is prepared using vegetable oil,
particularly, used or processed vegetable oil, which can be
obtained, for example, from the food industry. Vegetable oil is a
triglyceride extracted from a plant. A triglyceride is an ester of
glycerol and three fatty acids. Depending on the source, vegetable
oil contains a mixture of different types of fatty acids, for
example, saturated, mono unsaturated, poly unsaturated, omega 3,
omega 6 or omega 9 fatty acid. Most of the vegetable oils commonly
used for cooking (for example, olive oil, palm oil, sunflower oil,
corn oil, or peanut oil) contains one or more or all of these fatty
acids. The presence of these different types of fatty acids makes
vegetable oil a promising source for emulsifiers for drilling
fluids. Vegetable oils that have been used for cooking and been
disposed as waste could be used as a sustainable source for
emulsifier synthesis. Unused or unprocessed vegetable oil can also
be used for the emulsifier synthesis described here.
FIG. 1 is a schematic diagram of a drilling fluid circulation
system 10. FIG. 2 is a schematic diagram showing drilling fluid
flowing through a drill string 12 and an annulus 40 between the
drill string 12 and a wellbore 50. In wellbore drilling situations
that use a drilling rig, a drilling fluid circulation system 10
circulates (or pumps) drilling fluid (for example, drilling mud)
with one or more mud pumps. The drilling fluid circulation system
10 moves drilling fluid (mud, F) down into the wellbore 50 through
a drill string 12, and drill collars which are connected to the
drill string 12. The drilling fluid exits through ports (jets) in
the drill bit, picking up cuttings C and carrying the cuttings of
the wellbore 50. As seen in FIG. 1, the mud pump 30 takes suction
from mud tank 22 and pumps the drilling fluid F out discharge
piping 24, up with the standpipe 26, through rotary hoses 28,
through Kelly or top drive unit 31, and into a central bore of the
drill string 12, drill collars and drill bit as shown in FIG. 2.
Drilling fluid F and cuttings C returned to the surface of the
annulus 40. At the surface, the drilling fluid and cuttings leave
the wellbore 50 through an outlet (not shown) and are sent to a
cuttings removal system via mud return line 60 as seen in FIG. 1.
At the end of the return lines, drilling fluid F and cuttings C are
flowed onto a vibrating screen, for example, a shale shaker 62.
Finer solids can be removed using a sand trap 64. The drilling
fluid can be treated with chemicals stored in a chemical tank 66
and then provided into the mud tank 22, wherein the process can be
repeated.
The drilling fluid circulation system 10 delivers large volumes of
drilling fluid under pressure for the drilling rig operations. The
circulation system 10 delivers the drilling fluid to the drill stem
to flow down the drill string 12 and out through the drill bit
appended to the lower end of the drill stem. In addition to cooling
the drill bit, the drilling fluid hydraulically washes away debris,
rock chips, and cuttings, which are generated as the drill bit
advances into the wellbore 50. Thus, the drilling fluid is an
important part of the component drilling operation which can be
flowed through wellbore drilling system components, for example, as
rotary, coiled tubing, or casing, in different wellbore drilling
operations, for example, under balance drilling or overbalanced
drilling, to perform several functional tasks and facilitate safe,
trouble-free and economical drilling.
FIG. 3 is a flowchart of an example process 300 of producing
emulsifier using esterified waste vegetable oil. In some
implementations, the emulsifier can be used in other wellbore
fluids, for example, fracturing fluids, completion fluids,
stimulation fluids, or a combinations of them. At 302, esterified
waste vegetable oil is obtained. In some implementations, a methyl
ester of waste vegetable oil is obtained. For example, waste
vegetable oil (that is, vegetable oil that has been used for
cooking) is esterified to prepare a methyl ester of the vegetable
oil fatty acids and the derivatives thereof found in waste
vegetable oil.
At 304, a caustic soda solution is added to the methyl ester of the
waste vegetable oil. Adding the caustic soda solution changes the
reaction mixture into a suspension. In some implementations, the
caustic soda solution can be prepared by dissolving a quantity of
sodium hydroxide in water. Alternatively, other alkali hydroxides
can be dissolved in water to prepare the caustic soda solution. In
some implementations, the caustic soda solution can be added to the
methyl ester of the waste vegetable oil over a period of time. The
caustic soda solution can be added at an optimal rate. For example,
adding caustic soda solution at a rate of one milliliter per minute
can be an optimal rate in some situations. Fast adding will affect
the percentage of conversion of methyl ester of vegetable oil to
emulsifier as it forms suspension immediately, which will hinder
the caustic soda reaction with methyl ester.
At 306, the mixture is thermally treated. In some implementations,
the mixture can be stirred (or otherwise agitated) for a certain
duration at a temperature that is greater than room temperature for
six hours. Stirring facilitates and increases contact between the
caustic soda and methyl ester. Heating at the temperature creates
Brownian motion of the reaction mixture and accelerates reaction
kinetics.
At 308, the thermally treated mixture is maintained at a static
condition. In some implementations, the agitation of the thermally
treated mixture and the heating can be ceased to allow the mixture
to cool to room temperature. No other action can then be performed
on the mixture. Maintaining the mixture at the static condition can
allow the methyl groups to be cleaved off, resulting in the
emulsifier.
At 310, water is added to the reaction mixture to separate the oil
and water phases, thereby isolating the emulsifier. The water
volume can be 15-30% of the oil volume taken initially for the
reaction.
At 312, the pH of the mixture is adjusted. In some implementations,
the pH is adjusted by adding an acid to the reaction mixture until
the pH of the mixture reaches a level at which an oil phase
separates out from the reaction mixture.
At 314, the non-aqueous and aqueous phases are separated. In some
implementations, the two phases are separated by first transferring
the reaction mixture to a separation flask, from which the aqueous
phase is removed. In some implementations, additional water can be
added to the separation flask to wash and remove any remaining
inorganic salts in the non-aqueous phase. The remaining non-aqueous
phase along with emulsion is left in static condition to allow the
emulsion to de-foam. The de-foamation may further release water,
which can be removed as previously described. The non-aqueous phase
from which the foam has been removed is available as the
emulsifier.
FIG. 4 is a flowchart of an example process 400 of producing
esterified waste vegetable oil. For example, the esterified waste
vegetable oil produced by implementing process 400 can be used to
produce the emulsifier by implementing the process 300. In some
implementations, the additive can be used in wellbore fluids, for
example, drilling fluids (specifically, oil-based drilling fluids),
fracturing fluids, completion fluids, stimulation fluids, or a
combinations of them.
At 402, the waste vegetable oil including fatty acids is obtained.
In some implementations, the waste vegetable oil can be processed
vegetable oil produced as a byproduct by the food industry.
Throughout this disclosure, the term "substantially" represents a
permissible deviation of 5% from a disclosed quantity. The waste
vegetable oil can have a plastic viscosity of greater than
substantially 50 centipoise (cP) or 60.8 cP measured using a
multi-speed rotational viscometer. The waste vegetable oil can have
a plastic viscosity ratio of waste vegetable oil to mineral oil
that is greater than substantially 10 (for example, substantially
11.18). The waste vegetable oil can have a plastic viscosity ratio
of more than substantially 20 with respect to the plastic viscosity
of a very refined oil produced by Safra (Jeddah, Saudi Arabia) and
used for offshore drilling. Safra is a refined mineral oil. The
waste vegetable oil can have a plastic viscosity ratio of
substantially 24.12 with respect to the very refined oil produced
by Safra and used for offshore drilling. The waste vegetable oil
can have a plastic viscosity ratio of more than substantially 10
with respect to the plastic viscosity of mineral oils that are used
for oil-based drilling fluid formulations. These oils have very
similar viscosity value of around 10 cP although the plastic
viscosity of mineral oil is more than that of refined mineral oil
as expected. Mineral oil can be bought as mineral oil in the
market. Refined mineral oil is called Safra oil that is used in
offshore drilling as well.
The waste vegetable oil can include fatty acids with a short chain
alcohol. The short chain alcohol can include at least one or more
of methanol, ethanol, propanol, butanol, or combinations of them.
The fatty acids can include molecules averaging substantially from
16 carbon atoms to less than 20 carbon atoms.
At 404, impurities are removed from the waste vegetable oil. The
impurities, for example, food residues, can reduce the functional
capability of the waste vegetable oil. In some implementations, the
waste vegetable oil can be filtered, for example, quick filtered,
at low pressure, for example, a pressure range of substantially 5
pounds per square inch (PSI) to substantially 10 PSI. Impurities
can be removed from the waste vegetable oil using alternative or
additional methods.
At 406, the raw material waste oil is esterified. In some
implementations, the raw material waste oil is esterified in the
presence of a catalyst to produce alkyl ester products and
triglycerides. The catalyst can include at least one of sodium
hydroxide, potassium hydroxide, sodium alkoxide, potassium
alkoxide, or combinations of them. For example, the waste vegetable
oil can be esterified with methanol in the presence of sodium
hydroxide. At 408, the alkyl ester products and triglycerides are
separated. Example techniques for implementing portions of process
400 to produce the esterified waste vegetable oil are described
below. Alternative techniques can be implemented to produce the
esterified waste vegetable oil.
Removal of Impurities and Excess Water
A low pressure filtration cell can be used to remove impurities,
for example, burnt and unburned food residue, present in the waste
vegetable oil. The low pressure filtration cell can include filter
paper that has pore sizes that were less than 5 microns (.mu.m) to
remove impurities that were larger than 5 .mu.m. A constant
pressure of 5-10 PSI can be used on the low pressure cell for quick
filtration of a volume of the waste vegetable oil. Other filtration
media, adsorbents, or both, that are capable of removing all
impurities and excess water from the waste vegetable oil can be
used as alternatives or in addition to the low pressure filtration
cell. For example, a multi-cell filtration apparatus can be used
for removing the impurities.
Determination of Quantity of Catalyst
A quantity of catalyst required to process the waste vegetable oil
can be determined by titration method. To do so, for example, 1
milliliter (mL) of waste vegetable oil can be mixed with 10 mL of
isopropyl alcohol of 99.2% purity by volume. To this mixture, 2-3
drops of an indicator fluid (for example, phenolphthalein) can be
added. The indicator fluid can be added drop-by-drop into the
agitated waste vegetable oil until the color changes to pink. After
the endpoint, the mixture can be stirred for a while to check the
permanency of the pink color. The titration test can be repeated
three times to calculate the average amount of catalyst required to
reach the endpoint. After determining the average value of sodium
hydroxide (NaOH) based on the titration test results, a constant
value (for example, 3.5 grams (g)) can be added to determine the
total amount of catalyst (for example, between 4.18 g and 4.22 g)
required for 1 liter (L) of waste vegetable oil.
Esterification to Remove Triglycerides
The viscosity of the waste vegetable oil can be reduced to match
the mineral oil viscosity (around 12 cP) by esterifying the base
oil using methanol. To do so, a volume of methanol, for example,
20% of the original waste vegetable oil volume, and the mass of
NaOH (for example, 4.22 g NaOH/liter of waste vegetable oil) can be
mixed in a very dry condition (no detectable amounts of water)
using a magnetic stirrer and then added to the waste vegetable oil
in a container. The mixture can then be stirred for six hours using
the magnetic stirrer to complete the interactions.
Sedimentation
The total reaction product can be allowed to stay in static
conditions overnight to complete the sedimentation of glycerol and
sludge at the bottom of the container. During the initial settling
phase, the emulsion formed, can be broken by heating the processed
mass at about 80.degree. C. In some implementations, the emulsion
is formed due to the presence of some emulsion forming byproducts
in the ester layer. In some instances, adding about 10 mL of acetic
acid per liter of waste vegetable oil can break and prevent the
emulsion formation.
Separation and Washing of Esterified Oil
After complete sedimentation, the top clear esterified oil was
decanted slowly and washed for several hours using water while
stirring with a magnetic stirrer. Then, the esterified oil and the
washed water were kept in static condition overnight for effective
separation of oil and water phases. The separated oil phase was
decanted slowly to remove it from the water phase. The process of
washing was repeated, for example, twice.
EXAMPLE
The process 300 to produce the emulsifier was implemented as
described here. Substantially 300 milliliters (mL) of methyl ester
of waste vegetable oil was taken in a beaker having a magnetic
stirring bar and placed on a hot plate stirrer. The methyl ester
was stirred at substantially 500 rotations per minute (rpm). A
caustic soda solution was prepared by dissolving substantially 15
grams (g) of sodium hydroxide in 50 mL of water. The caustic soda
solution was added to the methyl ester over a period of
substantially two minutes, which turned the reaction mixture into a
suspension. The reaction mixture was stirred for substantially 6
hours at substantially 60.degree. C., and then allowed to be static
for substantially 16 hours, which resulted in the reaction mixture
becoming thick and of semi-solid consistency. Substantially 50 mL
of water was added to the mixture. Hydrochloric acid (substantially
31% by volume) was added drop-by-drop to the reaction mixture until
the pH of the reaction mixture was around 4-5, upon which an oil
phase separated out from the reaction mixture. The reaction mixture
was transferred to a separation flask. The aqueous phase, which was
separated from the non-aqueous phase by an emulsion layer, was
slowly and carefully removed from the separation flask.
Substantially 50 mL of water was added to the remaining non-aqueous
phase in the separation flask for washing and removing of any
inorganic salts that remained in the non-aqueous phase. The aqueous
phase formed again was removed slowly and carefully from the
separation flask, and the step was repeated. The remaining
non-aqueous phase along with the emulsion was left in static
condition to allow de-foamation of the emulsion. Water released
upon de-foamation was removed from time to time. Finally, the
non-aqueous phase was collected as a colorless liquid.
Thus, particular implementations of the subject matter have been
described. Other implementations are within the scope of the
following claims.
* * * * *