Entry to the Stockholm Junior Water Prize 2024

The Development of an Innovative Demulsifier
for the Separation of an Emulsion of
Water-Soluble Cutting Oils

Hyunseung Lee

South Korea

I.

Abstract:
Though water-soluble cutting oil is an essential material for metal-cutting processes, its

release into the water system prompts significant contaminations. Since the emulsion of waterand oil cannot be completely separated, it is difficult to recycle and often designated as waste forincineration. To solve this problem, I developed a more effective demulsifier using pine powder
with a lignin content of more than 50%. When pine powder and sulfuric acid were added to 5%
water-soluble cutting oil, the emulsion removal effect was confirmed. At first, the process took 3
weeks at room temperature, but it was later reduced to 1 hour at 80℃. To identify the
demulsifying component of pine powder, I conducted an experiment using pine extract,confirming that lignin is a demulsifying component. Then, by comparing calcium lignosulfonate
to sodium lignosulfonate, I confirmed that both substances had a high demulsifying effect, yetcalcium lignosulfonate showed a greater demulsification performance. As such, I confirmed thattreating 200 ml of water-soluble cutting oil emulsion with 0.016 g of calcium lignosulfonate andsulfuric acid (0.048 M) removes emulsion by nearly 100%. Also, I used the activated carbons tocompletely eliminate the yellow colorings from the separated water layer. The analysis has
demonstrated that the separated layer contains 0.006mg/L of phenols, while no other harmful
substances are detected, making the aqueous layer safe to discharge. Lastly, I applied thisdemulsification method to two types of waste cutting fluids, which have been stored for 1 day
and 3 months after the use, respectively. Although the color of the separated water layer was
more brown than the control group, the separation of emulsion was successful, highlighting its
potential application to real-life settings. Moreover, I performed a bottle test using calcium
lignosulfonate on the artificial emulsion made by combining crude oil and surfactant (Tween 20).
The lignosulfonate showed a superior demulsifying effect compared to the control group,
signifying that my demulsification method can be used not only for purifying water-soluble
cutting oil but also as a demulsifier in various fields, including the crude oil industry.

II.

Key Words:

Demulsifier, Emulsion, Water-Soluble Cutting Oil, Cutting Oil, Waste Cutting Oil, Lignin,
Sodium Lignosulfonate, Calcium Lignosulfonate, Sulfuric Acid, Seperation, Pine Tree Powder,
Pine Tree Extract, Activated Carbon, Crude Oil

2

III.

Abbreviations and Acronyms:

COD: Chemical Oxygen Demand

BOD: Biochemical Oxygen Demand

Acknowledgements:

IV.

I would like to express my sincere gratitude to Ms. Julie MacDonald, a science teacher
from Chadwick International, who provided invaluable guidance and feedback throughout the
research process. Also, I would like to give a special thanks to Korea Water Forum (KWF) for
this opportunity to develop my research project through a series of incubation sessions andparticipate in the prestigious Stockholm Junior Water Prize 2024.

Biography:

V.

Hyunseung (Henry) Lee is a rising Junior at Chadwick International School located at
Songdo, South Korea. He is a passionate explorer of water purification issues and marine
ecosystems, pursuing his interests in scientific discoveries through participating in various
international competitions. As a representative of South Korea, Hyunseung (Henry) Lee won agold medal at the Korea Science & Engineering Fair (‘23) and participated in the International
Science & Engineering Fair as an environmental engineering department.
VI.

Table of Contents:

1. Introduction………………………………………………………………………………….4-7
1.1. Water Soluble Cutting Oil……………………………………...………………………..4
1.2. Problems…………………………………………………………………………………5
1.3. Literature Review………………………………………………………………………..6
1.4. Objective…………………………………………………………………………………7
2. Materials and Methods………………………………………………………………………8-9
2.1. Preparation of Pine Tree Powder and Wood Materials…………………………………...82.2. Demulsification of Water-Soluble Cutting Oil Emulsion………………………………...82.3. Pine Tree Powder Extract………………………………………………………………...82.4. Demulsification Effect of Pine Tree Extract……………………………………………...83

2.5. Preparation of Lignin Samples……………………………………………………………82.6. Demulsification Effect of Lignin…………………………………………………………92.7. Activated Carbons for Purification of Aqueous Layer…………………………………...92.8. Water Quality Analysis of Purified Aqueous Solution…………………………………...92.9. Demulsification of Waste Cutting Fluids…………………………………………………92.10. Demulsification Effect on Crude Oil……………………………………………………93. Results and Discussion…………………………………………………………………….10-17
3.1. Effect of Pine Tree Powder and Sulfuric Acid on Demulsification……………………..10
3.2. Effect of Temperature on Demulsification………………………………………………11
3.3. Separating Emulsion using Pine Tree Extract……….…………………………………..12
3.4. Demulsification effect of various tree types…………………………………………….13
3.5. Demulsification effect of Lignin………………………………………………………...14
3.6. Purification of Separated Water Layer using Activated Carbon………………………...15
3.7. Safety Analysis on Separated Aqueous Layer…………………………………………..15
3.8. Application to Waste Cutting Oils………………………………………………………16
3.9. Demulsification Effect of Lignin on Crude Oil…………………………………………17
4. Conclusion…………………………………………………………………………………….18
5. References……………………………………………………………………………………..19**Unless otherwise noted, all visuals and graphs were made by the student researcher.

1. Introduction:
1.1 Water Soluble Cutting Oil:
Water-soluble cutting oil, a type of lubricant used by mixing with water, is generally usedin metal working and cutting processes, and is especially useful when solubility in water isrequired. This type of cutting oil offers high productivity by acting as a lubricant in metal
removal processes and is widely used in the current metal cutting industry. The main advantage
of water-soluble cutting oil is its excellent cooling effect. Since the specific heat of water-soluble4

cutting oil is more than twice that of non-water-soluble cutting oil, it is more effective whencooling the heat generated during the alloy cutting process. As water-soluble cutting oil iswater-based, it also offers the advantage of being non-flammable [1]. Owing to these advantages,
the global metalworking oil market was valued at approximately 2.4 billion USD in 2021 and themarket is expected to grow at an average of 4.2% per year to surpass 3.5 billion USD by 2030
[2].

Figure 1. Demonstration of how water soluble cutting oil is used in metal cutting industries,
including the cutting fluids tank (left), cutting fluids during metal cutting process (middle), and cutting
fluids before the use (right).

1.2. Problems:
Currently, the widespread use of water soluble cutting oil is followed by the generation of
more than 2 billion tons of waste-cutting oils every single year, which is enough to fill the entire
city of Stockholm with a tsunami of 75 m height [3]. The use of cutting fluids is prevalent inboth economically developed and underdeveloped countries, illustrating how the generation ofwaste cutting fluids is a global issue. However, as shown in Figure 2, unlike regular oil that
forms a layer on the surface of water, water-soluble cutting oil mixes readily with water; thewaste cutting fluids usually have the COD higher than 100,000mg/L and BOD over 10,000mg/L
due its emulsified state [3]. Therefore, discharged water-soluble cutting oil can cause the spreadof toxic compounds throughout water bodies, polluting water sources and causing destruction ofmarine flora and fauna ecosystems. As extremely small amounts of water soluble cutting oils
added to the to the lake, river, or ocean can contaminate the entire water body, water soluble
cutting oil is a significant international water issue.

5Figure 2. Illustration of (left) typical oil and water mixture that are immiscible and (right) cutting
oil and water mixture with emulsions. Orange color indicates oil and yellow color indicates water.

Furthermore, the purification of emulsions, consisting of 10 percent of water soluble
cutting oil and 90 percent of water, involves the separation of oil from water. This process
requires high thermal energy - about 800 ℃ of heat - leading to serious carbon emission andenvironmental pollution. Thus, incinerating the waste cutting oil is an environmentally
devastating and energy-inefficient process. One other solution to the treatment of waste cutting
oils is separating the oil from water through breaking the emulsions. This process is also called ademulsification, and current metal-cutting industries utilize various demulsification methods totreat the waste cutting oils.
1.3. Literature Review:
The methods currently used for demulsification of water-soluble cutting oil can bedivided into three main types. First, treating emulsions with chlorides of calcium, magnesium,
and aluminum can destabilize the emulsion and lead to agglomeration of water droplets. Thismethod is referred to as demulsification using inorganic salts, which is a prospectively effective
and inexpensive method. However, the effectiveness of inorganic salt may vary depending on thetype, concentration, and pH of the salts, which presents the inconvenience of having to choose
the right method for each situation. Moreover, when inorganic salts are released into nature, they
can increase water and soil salinity and produce toxic substances, posing threats to theenvironment. Also, inorganic salts are often used to separate water from the extracted petroleum,but they are widely ineffective for artificially created emulsions using emulsifiers. Thus,
inorganic salt could not completely separate the water soluble cutting oils [4].
Secondly, microorganisms are used to naturally decompose cutting oil. When cutting oil
is decomposed by microorganisms, a layer is formed between the oil and water and the water6

droplets agglomerate, enabling purification. Since no additional chemicals are added in thisprocess and the purification process is driven mainly by microorganisms, this method causes lessenvironmental pollution. However, the scope of application is limited to only biodegradable
cutting oil. Moreover, this approach is much less efficient than conventional methods, andcontamination during degradation by microorganisms can also cause malodor and corrosion andsuffer from performance degradation. Thus, microbial demulsification is also much more time
consuming, and also requires a significant amount of energy [5].
Lastly, the use of electrocoagulation with an electric current can destabilize emulsions toseparate cutting oil from water. Here, a redox reaction is triggered, forming agglomerates andprecipitates, facilitating the removal of oil by methods such as filtration. As an advantage, thetreated water can be discharged and the oil can be recycled for reuse. However, this method has
the disadvantages of high installation and maintenance costs and significant electrical energy
cost. In addition to the cost factor, there is also the environmental issue associated with the waste
generated after electrocoagulation [6].
As such, currently available cutting oil purification methods do not simultaneously satisfy
the requirement for both excellent performance and eco-friendliness. While demulsification
methods with high productivity often pose harms to the environment, the eco-friendly methods
generally tend to have poor performance and increased cost. However, most importantly, none of
the existing demulsification methods can not achieve a near 100% separation rate of oil andwater from the emulsion. Once the emulsion is completely separated, the COD and BOD of thesolution drops drastically, and the environmental threats of water soluble cutting oils can bealleviated. Thus, the demulsifier for complete separation of oil and water is essential for thetreatment of waste cutting fluids.
1.4. Objective:
The primary objective of this research is centered around developing a demulsification
method for water soluble cutting oil with near 100% separation ability of oil and water. After thecomplete separation of the emulsion, the water layer should be discharged without any potential
harm to the environment, while the remaining oil layer can either be reused or burned as a fuel.

72. Materials and Methods:
2.1. Preparation of pine tree powder and wood materials:
1. Pine tree powder (with a lignin content of ≥50%) from the microbial degradation ofcellulose and hemicellulose was prepared. By heating at 200 ℃ for 10 min, pine tree
powder samples with increased hydrophobicity and lipophilicity were prepared.
2. Pine and fir trees were ground to prepare wood chips with a size of ≤ 3mm.
2.2. Demulsification of water-soluble cutting oil emulsion:
1. Water-soluble cutting oil solution (5%) was prepared by adding 10 ml of water-soluble
cutting oil (SY-100, Samyuk Special Oil Solution Co., Ltd.) to 190 ml of distilled water.
2. After adding 200 ml of the 5% water-soluble cutting oil to a 600 ml beaker, a certain
amount of 95% sulfuric acid (Daejung) was added and mixed.
3. The pre-prepared pine tree powder (10 g) was added to the beaker, either in powder formor as powder in a tea bag.
4. The demulsification effect was observed at various temperatures and the transmittance(%T) at 600 nm was measured and recorded.
2.3. Pine tree powder extract:
1. After using pine tree powder to demulsify water-soluble cutting oil (SY-100), an aqueous
solution layer was prepared by filtering with filter paper.
2. Using distilled water as a solvent, pine tree powder was added to a 1 L flask and an
autoclave was used for extraction at 121 ℃ for 1 h.
2.4. Demulsification effect of pine tree extract:
1. Using varying concentrations of the extract, the demulsification effect of the pine tree
extract on 5% water-soluble cutting oil was measured with variation of the pH,
temperature, and time.
2. The transmittance (%T) was measured and graphically plotted to determine the degree
and rate of separation.
2.5. Preparation of lignosulfonate samples:81. Calcium lignosulfonate and sodium lignosulfonate were purchased from Daemyung
Chemical.
2.6. Demulsification effect of lignin:
1. The water-soluble cutting oil purification effect of calcium lignosulfonate and sodium
lignosulfonate was investigated.
2. For this purpose, the same 5% water-soluble cutting oil was used and the degree ofseparation was measured while adjusting the amount of lignin, pH, and time.
3. The transmittance (%T) was measured and graphically plotted to determine the degree
and rate of separation.
2.7. Activated Carbons for Purification of Aqueous Layer
1. Activated Carbons (Shin Kwang Chemical) are prepared to purify the separated waterlayer from the cutting fluids.
2. Three different types of activated carbons, including 40 mesh, 60 mesh, 200 mesh, areused, and the solution was treated under a magnetic stirrer for 4 hours, followed by thecentrifugation process.
2.8. Water quality analysis of purified aqueous solution:
1. The final separated aqueous layer of the solution was sent to the Seoul National
University National Instrumentation Center for Environmental Management (NICEM)
for more accurate water quality analysis and to determine whether there are any
remaining substances that may cause harm to the environment.
2.9. Demulsification of Waste Cutting Fluids
1. Obtained two types of waste cutting oils from Hosung Precision (Incheon, Korea); thefirst waste cutting fluid has passed 1 day after its use, and the second waste cutting fluid
has passed 3 months after its use.
2. Emulsion of waste cutting fluids has been separated using the calcium lignosulfonate andsulfuric acid, following the same method as above.
2.10. Demulsification effect on crude oil:9

1. By adding 175 ml of distilled water, 5 ml of Tween-20, and 20 ml of crude oil (suppliedby Eil Industrial Laboratory) to a 200 ml beaker, an emulsion was formed by vigorously
stirring at 60 ℃.
2. After adding 22 ml of the prepared emulsion to a test tube, the experimental group wastreated with calcium lignosulfonate (0.05 g/L) and the demulsification effect was
examined.
3. A test tube was used to conduct a bottle test and the test tube height was used to measure
the volume of the aqueous layer (22 ml) to determine the demulsification efficiency.

3. Results and Discussion:
3.1. Effect of Pine Tree Powder and Sulfuric Acid on Demulsification:
From the previous projects, I created a pine tree powder, which is an eco-friendly oil
absorbent created using pine trees with increased lignin content. Due to its hydrophobic
nature, pine tree powder is effective when absorbing oils on the surface of water bodies. Thus,
I first attempted to demulsify the water soluble cutting oils using the pine tree powder due to
its renowned excellence as an oil absorbent. First, I treated the water soluble cutting oils using
only the pine trees, but the demulsification effect did not appear. Then, through the literature
review, I identified the effect of sulfuric acid on destabilizing the emulsions, and I added
sulfuric acid along with the pine tree powder to observe the demulsification process of watersoluble cutting oils. Although it took 2~3 weeks, the emulsion was separated in theexperimental group that was treated with sulfuric acid, unlike the control group that was nottreated with sulfuric acid, as shown in the figure 3. When only the sulfuric acid was added tothe solution, the demulsification effect did not appear, but a thin layer of oil was formed on thesurface of the emulsion. Accordingly, the demulsification effect of pine tree powder was
confirmed, and at the same time, it was found that pH is an important factor affecting thedemulsification of water-soluble cutting oil.

10Figure 3. Demulsification effect of sulfuric acid and pine tree powder confirmed through the adding
12g of pine tree powder to 200ml of cutting fluids (5%), along with 0ml, 10ml, 20ml, and 40 ml ofsulfuric acid. The left photo compares the demulsification process between Day 0 and Day 21 of thereaction, while the right photo is a separated oil layer after adding only sulfuric.

3.2. Effect of Temperature on Demulsification:
In the subsequent investigation, pine tree powder was used by placing it in a tea bag(PET) and the reaction temperature was set for 25℃, 60℃, and 80 ℃. According to the figure 4,
the time required to demulsify the emulsion was reduced from 2‒3 weeks at room temperature to
three days at 60 ℃, and nearly 1 hour at 80 ℃, signifying the importance of temperature during
demulsification. However, as the demulsification effect beyond 80 ℃ had no significant
difference, I concluded that heat treating the emulsion at 80 ℃ is the most effective and efficient.

Figure 4. Amount of time consumed to separate the emulsion of cutting fluids for each temperature,including 25℃, 60℃, and 80 ℃, organized in a graph (left) and photo (right).

3.3. Separating Emulsion using Pine Tree Extract:
As the sulfuric acid forms the thin oil layer on the surface, I hypothesized that pine tree
powder consistently absorbs oil on the top of the emulsion, facilitating the demulsification.
However, according to the hypothesis, the demulsification process should work for any types of11

oil absorbent but not only pine tree powder. Thus, I used the polypropylene oil absorbent insteadof pine tree powder, along with the sulfuric acid, to test the demulsification effect.

Figure 5. The effect of pine tree extract in separating the emulsion of cutting oils, illustrated in a photo(left) and graph (right). Pine tree extract and cutting oil have three different ratios, - “extract 60” on thegraph signifies that 60% of the solution is pine tree extract and remaining 40% is cutting fluids.

However, when polypropylene oil absorbent was used for demulsification instead of pinetree powder, the polypropylene oil absorbent had no effect. Therefore, it was determined that
demulsification was not due to oil absorption by pine tree powder, but the presence of ademulsifier component in pine tree powder. As the experiment progressed, the aqueous layer
with the oil removed turned a bright yellow color, which was determined to be due to thecomponent extracted from the pine tree powder. Thus, the effectiveness of the aqueous layer for
purifying water-soluble cutting oil was investigated. According to figure 5, the result showed thatthe emulsion was separated more effectively as the concentration of the extract increased. Thus,
the pine tree extract generated by using water as a solvent was also confirmed to be effective fordemulsification. Therefore, it was determined that a certain demulsifier component inside thewater-soluble pine tree extract facilitates the separation process.
3.4. Demulsification effect of various tree types:
Another experiment was conducted to identify the demulsifier component in pine tree andpine tree extract with water as a solvent. Fir tree bark, pine tree bark, and waste wood powder
collected from the mountain were used as the experimental groups. As shown in figure 6, allthree experimental groups had a demulsification effect, but the result demonstrated that the
demulsification effect was inferior to that in the previous experiment using pine tree powder.

12

Figure 6. The demulsification effect of various tree types, including fir tree bark, waste wood powder,pine tree pellet, and pine tree bark (same amount of sulfuric acid added for all samples).

In attempts to identify the demulsifier component in the pine tree extract, we contacted
various laboratories, including the KIST Advanced Analysis Center, but the laboratories
notified us that HPLC analysis could not be performed due to the difficulty in procuring thelignin standard solution analysis. Moreover, we were also notified that FTIR analysis would be
difficult because the sample is an aqueous matrix. Nonetheless, based on the fact that pine tree
powder with high lignin content demonstrated superior demulsification effect than other typesof tree samples and all tree samples showed demulsification effect to certain extent, I postulated
that the lignin, a common component among trees, may be the demulsifying agent. Also, in theprevious research, I have used the Lignin Klason Method, which involves the use of sulfuric
acid to obtain lignin from the wooden materials. As my demulsification process also consists of
the assistance from the sulfuric acid, I draw a logical conclusion that lignin facilitates thedemulsification of water soluble cutting oils. Accordingly, calcium lignosulfonate and sodium
lignosulfonate were purchased from Daemyung Chemical and used in the experiment.
3.5. Demulsification effect of Lignin:
I used both calcium lignosulfonate and sodium lignosulfonate instead of pine tree
powder to separate the emulsion of water soluble cutting oils. As shown in figure 7, both typesof lignosulfonate demulsified the mixture of water and water-soluble cutting oil, where calcium
lignosulfonate was found to be more effective than sodium lignosulfonate. In addition,
demulsification was facilitated as the amount of lignosulfonate increased, but there was nodifference in the effect beyond a certain amount. Also, the transmittance decreased at 3 hours,
but it was determined that this was due to the increase in the amount of lignosulfonate.

13

Figure 7. Demulsification effect of calcium lignosulfonate and sodium lignosulfonate visualized in graphs(0.01g, 0.016g, and 0.025g signifies the amount of lignosulfonate added to the emulsion).

The effect of the amount of sulfuric acid and lignosulfonate on demulsification was investigated.
As shown in figure 8, when the concentration of sulfuric acid increased, both types oflignosulfonate showed a greater demulsification effect, whilst increasing the amount oflignosulfonate also had a greater effect on demulsification. However, the amount oflignosulfonate was more important than the amount of sulfuric acid, as the demulsification effectdid not appear unless a certain amount of lignin or more was added. Most importantly, none ofthe previous literature has been conducted regarding the effect of lignin as a demulsifier,contributing to the novelty of my finding.

Figure 8. Effect of sulfuric acid in separating the emulsions, along with two types of lignosulfonates,
visualized in graphs (0.037M and 0.048M signifies the morality of sulfuric acid added to the emulsion).

3.6. Purification of Separated Water Layer using Activated Carbon:
Then, I treated the separated water layer using 3 different types of activated carbon tocompletely eliminate the coloring. The color of the water layer derives from the pigment in the
cutting fluids, varying from yellow to dark-brown color by different concentration of the cutting
14

oils and the amount of lignin added. As a result, the colorings present in the separated waterlayers were completely eliminated, and the water layer has become transparent as shown infigure 9.

Figure 9. Effect of activated carbons in purifying the separated water layer from the emulsion, where
sample A is 200 mesh, sample B is 60 mesh, and sample C is 40 mesh.

3.7. Safety Analysis on Separated Aqueous Layer:
To investigate the identity and quantity of the remaining oil components with potential
detrimental environmental impact in the demulsified aqueous layer, twenty items were sent toSeoul National University NICEM for analysis, including phenols. According to figure 10, theresults showed that phenols accounted for 0.006 mg/L, while other components were notdetected. Therefore, it was determined that the demulsified aqueous layer can be discharged
safely into sewage without harm to the environment.

Figure 10. Table with amount of Phenol, Benzene, Toluene, and Dichloromethane detected in theseparated water layer of the cutting fluids.

3.8. Application to Waste Cutting Oils:
Then, I applied my demulsification process to waste cutting oils to identify the potential
application of my demulsifier in real-life settings. Unlike the water soluble cutting oils in thelaboratory that only contains the mixture of oil and water, the waste cutting oils from the field
15

consists of various unknown substances that are added during the metal cutting processes. Thus,
I demulsified the waste cutting fluids A and B, which are used in real industrial settings. While
cutting fluid A is just used to cut the metal, cutting fluid B has been stored for 3 months after theuse, as shown in figure 11.

Figure 11. Cutting fluids in a laboratory setting (control), waste cutting oil A (stored for 1 day after theuse), and waste cutting oil B (stored for 3 months after the use) before the separation of emulsion.

As a result, the emulsion has been separated, forming a layer between oil and water.
However, the color of the water layer was more brown than the control group. Also, themicrofluidic chip and foam stayed in the oil layer, leaving no additive materials to the waterlayer, as shown in figure 12. Thus, the water layer can be discharged after the treatment, while
the remaining contents in the oil layer (less than 2~3%) can be incinerated after collecting theoils.

Figure 12. Cutting fluids in a laboratory setting (control), waste cutting oil A (stored for 1 day after theuse), and waste cutting oil B (stored for 3 months after the use) after the separation of emulsion.

3.9. Demulsification Effect of Lignin on Crude Oil:
16

Crude oil obtained with cooperation from Eil Industrial located in Yeosu, Jeollanam-do,
was used to evaluate the demulsification effect of the extract on crude oil. Tween-20, a non-ionicsurfactant, was used to artificially form an emulsion by electronic stirring. The bottle test was
performed at 60 ℃ with 0.05 g/L of calcium lignosulfonate as the final concentration.

Figure 13. Demulsification effect of calcium lignosulfonate on separating the artificial emulsions createdusing surfactant (Tween-20) and crude oil, visualized in a graph (left) and photo (right). In the photo, theleft sample is treated with calcium lignosulfonate and the right sample is not treated at all, and theirseparation was recorded in 5 min, 10 min, 60 min, and 80 min terms.

According to figure 13, the results showed that lignin has an excellent demulsification
effect compared to the control group, and nearly 100% separation of the aqueous and crude oillayers was achieved within 20 min. In contrast, the control group showed a pattern of continuous
separation of the aqueous layer, albeit at a relatively slower rate, and separation stalled at 90%
even after 80 min. Therefore, the experimental results confirmed that lignin has the potential for
use as a demulsifier not only for water-soluble cutting oil, but in various fields including thecrude oil industry.

4. Conclusion:
In conclusion, as shown in figure 14, I succeeded in separating the water and oil from theemulsion up to near 100%, becoming the first demulsifier in the world with complete separation
ability. While separated water can be discharged without harms to the environment, the oil caneither be incinerated or reused.

17

Figure 14. Photo of separated water layer and oil layer from the cutting fluids, where 5% cutting oil(SY-100) was treated with 0.5ml of sulfuric acid (0.05M) for 3 hours at 80 ℃.

Also, I discovered that lignin is effective for artificial emulsion created using surfactant(Tween-20) and water, posing its potential use for more real-life applications including thepetroleum industry. Lastly, I used the same method to separate the waste cutting fluids into oil
and water. Unlike the laboratory setting, waste cutting fluids consist of various unknown
substances that are added during the metal cutting processes. Thus, demulsifying the waste
cutting fluids reinforced the potential application of my demulsifier into real-life industrial
settings.
In future, I aim to identify the demulsification mechanism of lignin. Also, I have to test
the demulsifier with various types of waste cutting fluids to ensure that my method is applicable
to industries in real-life. Finally, I attempt to reduce the amount of heat energy used to decrease
the total amount of carbon emissions generated during the demulsification process.

5. References:[1]

Kwon Daegyu, A Study on the Relation between Surface Roughness and Cutting Fluids,

RISS, 2011, https://www.riss.kr/search/detail/DetailView.do?p_mat_t
ype=be54d9b8bc7cdb09&control_no=9c9af342e208fd93 ffe0bdc3ef48d419&outLink=K, 15
Dec. 2023

18

[2]

“Demulsifier Market Size and Growth Forecast Report, 2022-2030.” P&amp;SIntelligence, www.psmarketresearch.com/market- analysis/demulsifier-market. 25 Dec. 2023.
[3] Danilo Spasiano, Andrea Petrella, Vito Lacedra. “Chemical Destabilization of Fresh andSpent Cutting Oil Emulsions: Differences between an Ecofriendly and Two Commercial
Synthetic Lubricants”, MDPI Sustainability, 15 July 2020
[4] Zhuang Qi, Zhiqian Sun, Ning Li, Qi Chen, Wenchuan Liu, Wangqing Li, Effect of inorganic
salt concentration and types on electrophoretic migration of oil droplets in oil- in-water
emulsion: A molecular dynamics study, Journal of Molecular Liquids, Volume 367, Part B, 2022
[5] Kaiming Peng, Wanqi Liu, Yongjiao Xiong, Lijun Lu, Jia Liu, Xiangfeng Huang, Emulsion
microstructural evolution with the action of environmentally friendly demulsifying bacteria,
Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 553, 528-538, 2018
[6] Abdulla, Firdos. M., and N.H. Abdurahman. “Demulsification of crude oil emulsion via
electrocoagulation method.” Journal of Chemical Engineering and Industrial Biotechnology, vol.
3, no. 1, 97–105, 201819