ABSTRACT
Lubricating
oils are viscous liquids used for lubricating moving part of engines and
machines. Since lubricating oils are obtained from petroleum – a finite
product, and with dwindling production from world oil reserves, the need arises
more than ever, to recycle used lubricating oils.
Accordingly, this research work focuses on comparative study of two methods of recycling of used Engine oil using glacial acetic acid and formic acid treatment methods. A recycling process of the used lube oil was carried out which eventually led to comparison of results of the recycled oil with the fresh lube oil using ASTM standards. Tests carried out on the used, fresh and recycled lube oils include: flash point, viscosity at 55°C, specific gravity/density, appearance and pour point. The results show that recycled lubricating oil had the following properties: flash point was 200°C for the acetic and formic acids, as compared with 170°C for untreated oil, Also the pour point of the engine oil using acetic and formic acids are 6°C and 5°C respectively. It has been shown that base oils and oils’ additives are slightly affected by the acetic acid. Upon adding acetic and formic acid to the used oil, two layers were separated, a transparent dark colored oil and a black dark sludge at the bottom of the container. The comparison showed that the recycled oil produced by acetic acid and formic acid treatment showed excellent results in the properties of the oil comparable to the fresh oil.
TABLE OF CONTENT
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
Table of contents vi
CHAPTER ONE
INTRODUCTION 1
Background of Study
Problem Statement
Objective of Study
Justification of Study
Scope of Study
CHAPTER TWO
LITERATURE REVIEW
2.1 Lubricating Oil
2.1.1 Use in vehicle
2.2 Engine Oil
2.2.1 Used Engine Oil
2.2.2 Contamination
2.2.3 Contaminants in used Lubricating Oil
2.2.4 Efeects of Oil Contaminants
2.2.5 Physical and Chemical Properties of used Engine
2.2.6 Impacts of used Lubricating Oil
2.3 Used Oil Recycling and Reuse
2.3.1 Impacts of Used Oil Recycling and Reuse
2.4 Recovery Methods
2.4.1 Solvent Extraction Methods
2.4.2 Membrane Technology
2.4.3 Acid Treatment Process
CHAPTER THREE
MATERIALS AND METHODS
3.1 Materials
3.1.1 Experimenta Materialsl
3.1.2 Equipment used
3.1.3 Reagents
3.2 Methods
3.2.1 Material Preparation
3.2.2 Experimental Procedures
CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Results
4.2 Discussion
4.2.1 Appearance
4.2.2 Flash Point
4.2.3 Viscosity at 55◦C
4.2.4 Specific gravity
4.2.5 Pour Point
CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
5.1
Conclusion
5.2
Recommendation
References
Appendix/Appendices
CHAPTER
ONE
INTRODUCTION
1.1 Background
Information
Lubricating
oils are viscous liquids used for lubricating moving parts of engines and
machines. Lubricating oils are obtained from petroleum finite product and with
dwindling production from the world oil reserves, it is essential to recognize
that all used oil should be disposed using controlled method disposals.
Lubricating oil is used to provide a film between the moving part of machines
engines to prevent wear and tear. This
may result in groundwater and soil contamination. Recycling of such
contaminated materials will be beneficial in reducing engine oil costs. In
addition, it will have a significant positive impact on the environment. The
conventional methods of recycling of waste engine oil either requires a high
cost technology such as vacuum distillation or the use of toxic materials such
as sulfuric acid. These methods also produce contaminating by-products which
have highly sulfur levels, especially in the Kurdistan region/Iraq. Lubricant
oils have been used primarily for reducing friction between moving parts of various
machinery or equipment, minimize material wear, improve the efficiency of
equipment /machinery and for fuel and energy savings. Access to lubricants is
essential to any modern society and not only does lubrication reduce friction
and wear by interposition of a thin liquid film between moving surfaces, but it
also removes heat, keeps equipment clean, and prevents corrosion. One of its
important applications includes gasoline and diesel engine oil.
Waste
lubricating oil refers to the engine oil, transmission oil, hydraulic and
cutting oils after use. It is also refers to the degradation of the fresh
lubricating components that become contaminated by metals, ash, carbon residue,
water, varnish, gums, and other contaminating materials, in addition to asphaltic
compounds which result from the bearing surface of the engine. These oils must
be changed and removed from the automobile after a few thousand kilometers of
driving because of stress from serious deterioration in service. The amount of
lubricating oils that is collected annually in Europe and USA is very large,
approximately 1.7 to 3.5 million tons. This large amount of waste engine oils
has a significant impact on both economical and environmental aspects. They
cost millions of dollars to manufacture and represent a high pollutant material
when disposed of. If discharged into the land, water or even burnt as a low
grade fuel, this may cause serious pollution problems because they release
harmful metals and other pollutants into the environment.
As stated
earlier, When lubricating oils are used in service, they help to protect
rubbing surfaces and promote easier motion of connected parts. In the process,
they serve as a medium to remove high build up of temperature on the moving
surfaces. Further buildup of temperature degrade the lubricating oils, thus
leading to reduction in properties such as: viscosity, specific gravity, etc.
Dirts and metal parts worn out from the surfaces are deposited into the lubricating oils. With increased time of
usage, the lubricating oil loses its lubricating properties as a result of
over-reduction of desired properties, and thus must be evacuated and a fresh
one replaced. It is also vital to note that typical lubricating oil contains
90% base oil, most often petroleum fractions called mineral oils and <10%
additives. The chemical breakdown of these additives during use resulted to
build up of halogenated hydrocarbons in the oil. Polycyclic Aromatic
Hydrocarbons (PAHs) as well as other polycyclic compounds are generated and accumulate
in the oil (Wong & Wang, 2015) together with metals from wear and tear of
the engine being lubricated (Chuug et al., 20017). These compounds gradually
reduces its quality leading to change in its physical and chemical properties
and thereby deteriorated (Kamal & Khan, 2013).
A recommended solution for this issue is the
recovery of the lubricating oil from the waste oil. Recycling processes using
nontoxic and cost effective materials can be an optimum solution. Acid-clay has
been used as a recycling method for used engine oil for a long time. This
method has many disadvantages; it also produces large quantity of pollutants,
is unable to treat modern multigrade oils and it is difficult to remove
asphaltic impurities. Solvent extraction has replaced acid treatment as the
method of choice for improving the oxidative stability and
viscosity/temperature characteristics of base oils. The solvent selectively
dissolves the undesired aromatic components (the extract), leaving the
desirable saturated components, especially alkanes, as a separate phase (the
raffinate. In one study] a mixture of methyl ethyl ketone (MEK) and 2-propanol
was used as an extracting material for recycling used engine oils.
Although
the oil resulting from this process is comparable to that produced by the
acid-clay method, its cost is high. Expensive solvents and vacuum distillation
are required to carry out this method. Recently propane was used as a solvent.
Propane is capable of dissolving paraffinic or waxy material and intermediately
dissolved oxygenated material.
1.2 Problem Statement
Large quantities of used engine oil from
different sources are disposed as
harmful waste into the environment in rivers and lakes and this creates
series of problem as they contaminate fresh water and marine lives. Roughly one
gallon of used engine oil would contaminate one million gallon of water
including fauna and flora.
1.3 Objective of Study
This
research study focuses on the comparative study of treatment methods for used
engine oil, and its recovery methods. It addresses recycling of waste engine
oils treated using acetic acid. A recycling process was developed which
eventually led to comparable results with some of the conventional method.
The specific objectives are as follows;
To ensure that pure oil is gotten from waste engine oil
Assess the recovery capacity of the acetic acid process by characterizing the recovered oil and comparing it with the virgin oil.
To ensure low cost of recycling waste oil.
1.4 Justification of the Study
This research
is of great importance to mankind and the academia.The method of waste oil
treatment adopted in this research provides a lower cost process in comparison
with the conventional methods due to the low cost of the acid and the moderate
conditions of the process. The recycled oil obtained by this method has been
shown to have potential for reuse as an engine lubricant.
Furthermore
this new process of recycling of used engine oil did not emit poisonous gases
like sulfur dioxide to the atmosphere. In addition, glacial acetic acid has
less of a negative impact on the processing equipment compared with sulfuric
acid. Lower amount of additives may be required for the base oil recycled by
acetic acid-clay method due its low reactivity with the used oil.
1.5 Scope of the Study
In order to obtain the objectives stated above, spent engine oil has be recycled at
low cost this will ensure optimum productivity. Also a comparative analysis of
spent engine oil, new engine oil, and the recovered engine oil will be carried
out and some parameters such as viscosity, specific gravity, pour point and
flash point will be tested for.
CHAPTER TWO
LITERATURE REVIEW
2.1
Lubricating Oil
A lubricant is a substance, usually organic,
introduced to reduce friction between surfaces in mutual contact, which
ultimately reduces the heat generated when the surfaces move. It may also have
the function of transmitting forces, transporting foreign particles, or heating
or cooling the surfaces. The property of reducing friction is known as
lubricity.
Lubricating
oil is the very stable, non-volatile and smallest fraction of crude petroleum.
As petroleum products are essentially composed of hydrocarbons, lubricating
oils have hydrocarbon structures, containing from 20 to 70 carbon atoms per
molecule.
The
lubricating oil molecules can be divided into three broad groupings i.e.
paraffinic, naphthenic and aromatic based on functional group. Paraffinic molecules
are predominantly straight chains, tend to be waxy, have a high pour point,
good viscosity and better temperature stability. Naphthenic molecules are
straight chains with a high proportion of five and to a lesser extent six
membered ring structures. They tend to have a low pour point. For this reason
they are used as refrigeration oils. They are highly carcinogenic and are
little used in engine oil. Aromatics are straight chains with six membered ring
benzene structures. In real life applications no sharp distinction exists
between these various groupings as many lubricating oil molecules are a
combination, to varying degrees, of the different types of hydrocarbons
(Yu-Lung & Chun-Chu, 2010).
Lubricating
oils are fluids such as engine oils, gear, hydraulic oils, turbine oils, etc.,
used to reduce friction between moving surfaces. They also serve to remove heat
from working parts in machinery created by moving surfaces and provide a
protective layer on the metal surfaces to avoid corrosion. They also act as a
sealant to fill the microscopic ridges and valleys in any metal surfaces to
increase the machinery efficiency. Furthermore, they serve as a cleaning agent
to carry away dirt or other debris that may damage the bearings or other parts
that are operated in tight tolerance. Debris is removed through the engine oil
filter or the transmission filter.
Lubricating
oils are usually blended with a number of chemical additives to provide
products that last longer and allow the machinery to work better under severe
operating conditions.
However,
performance of the lubricants deteriorates over time as the additives are
chemically changed and the oil becomes contaminated with various unwanted
pollutants as a result of many physical and chemical interactions (Dennis,
2010).
There are
two basic categories of lubricating oil: mineral and synthetic. Mineral oils
are lubricating oils refined from naturally occurring crude oil. Synthetic oils
are lubricating oils that are manufactured. Mineral lubricating oils are currently
the most commonly used type because of the low cost of extracting the oils from
crude oil. Additionally, mineral oils can be manufactured to have a varying
viscosity, therefore making them useful in a wide range of applications.
Lubricating
oils of different viscosities can be blended together, and it is this ability
to blend them that makes some oils so useful. For example, common engine oil is
generally a blend of low viscosity oil to allow for easy starting at cool
temperatures and a high viscosity oil for better performance at normal running
temperatures.
2.1.1 Use
in Vehicles
The use of
lubricating oils in vehicles is vital to their operation. When an engine is
properly lubricated, it needs to put less work into moving pistons as the
pistons glide easily. In the long run, this means that the car is able to
operate while using less fuel and run at a lower temperature. Overall, the
proper use of lubricating oil in a car improves efficiency and reduces the
amount of wear and tear on moving engine parts.
2.2 Engine
Oil
Engine oil,
or engine lubricant is any of various substances comprising base oils enhanced
with various additives, particularly anti-wear additive in addition to
detergents, dispersants and, for multi-grade oils, viscosity index improvers.
Engine oil is used for lubrication of internal combustion engines. The main
function of engine oil is to reduce friction and wear on moving parts and to
clean the engine from sludge (one of the functions of dispersants) and varnish
(detergents). It also neutralizes acids that originate from fuel and from
oxidation of the lubricant (detergents), improves sealing of piston rings, and
cools the engine by carrying heat away from moving parts.
2.2.1 Used Engine Oil
This can be
referred to as any petroleum -based or synthetic oil that has been used. It
could also be referred to as spent oil. During normal use, impurities such as
dirt, metal scrapings, water or chemicals can get mixed in with the oil or be
generated in it due to thermal degradation or oxidation. Therefore, the oil
quality gradually decreases to a level that the used oil should be replaced by
a new one. Disposing the used oil off in nature creates an intense dangerous
pollution. But by proper recovery and refinement of it, a lot of valuable product
can be obtained.
Generally
lubricating oil becomes unfit for further use for two main reasons:
accumulation of contaminants in the oil and chemical changes in the oil. These
effects interfere with the basic properties of lubricating oil which are peculiar
for their effective performance during application (Awaja & Pavel, 2016).
2.2.2 Contamination
Engine oil
contamination also causes deterioration of the oil. Some of the more common
contaminant sources include dirt, sand and dust from the air, soot, unburned
fuel in the oil, water from condensation of the combustion process, wear metal
particulates that the oil filter cannot trap and hold, corrosion by-products
and additive elements that have degraded. In addition dirt, sand and dust can
continue to enter the engine and, in addition to creating more wear debris,
combine with other contaminants and cause more damage than they would
separately.
One of the
many by-products of combustion is soot. Soot can be highly abrasive as well as
cause filters to become filled and/or plugged in extreme cases. Another
contaminant is acidic by-products of combustion, which can produce a highly
corrosive mixture and cause corrosion and pitting of internal engine components
and additional generation of wear debris. These same acidic solutions can also
mix with water inside the engine and form an emulsion that can cause problems
with oil filters and passageways (Layzell, 2010).
Yet another
source of contamination is fuel. A charge of fuel is rarely 100% burned during
the combustion process. This unburned fuel can mix with the oil present in the
cylinders. Fuel contamination can also be caused by worn sealing components
such as excessive piston ring to cylinder clearances allowing unburned fuel to
blow-by the rings.
When motor
oil is diluted with fuel the viscosity is lowered. If this reaches extremes of
contamination excessive wear and engine damage can take place and may lead to
significant deterioration of the different properties of the oil (Chia-Yu,
2014).
2.2.3 Contaminants
in used Lubricating Oil
The main
constituents of waste lubricating oils are the base oil, degraded additives,
metallic debris, oxidation products and carbon soot. A large number of
additives are used to impart performance characteristics to the lubricants. The
main additives are antioxidants, detergents, anti-wear elements, metal
deactivators, corrosion inhibitors, rust inhibitors, friction modifiers,
extreme pressure withstanding elements, antifoaming agents, viscosity index
improvers, demulsifying or emulsifying agents and stickiness improver.
During their
use, these additives lose their characteristics rendering the lube oil non
usable for lubricating purpose. In addition, during their use, the lubricating
oils and the metal processing oils pick up fractions of various metals as a
result of wearing out of components. The concentration of these impurities
depends purely on the application to which the particular oil is put to
(Diphare et al., 2013).
Generally,
lubricating oil loses its effectiveness during operation due to the presence of
certain types of contaminants. These contaminants can be divided into
extraneous contaminants and products of oil deterioration.
2.2.4
Effects of Oil Contaminants
Due to its
chemical composition, worldwide dispersion and effects on the environment, used
engine oil is considered serious environmental problem. Most current motor-oil
lubricants contain petroleum base stocks, which are toxic to the environment
and difficult to dispose of after use. Over 40% of the pollution in America's
waterways is from used motor oil. Used oil is considered the largest source of
oil pollution in the U.S. harbors and waterways, at 1,460 ML (385×106 US gal)
per year, mostly from improper disposal. By far the greatest cause of engine
oil pollution in oceans comes from rural and urban street-runoff, much of it
caused by improper disposal of engine oil. One US gallon (3.8 l) of used oil
can generate a 32,000 m2 (8 acres) slick on surface water, threatening fish,
waterfowl and other aquatic life. According to the U.S. EPA, films of oil on
the surface of water prevent the replenishment of dissolved oxygen, impair
photosynthetic processes, and block sunlight. Toxic effects of used oil on
freshwater and marine organisms vary, but significant long-term effects have
been found at concentrations of 310 ppm in several freshwater fish species and
as low as 1 ppm in marine life forms. Engine oil can have an incredibly
detrimental effect on the environment, particularly to plants that depend on
healthy soil to grow. There are three main ways that motor oil affects the
environment. They include;
i.
Contaminating
water supply
ii. Contaminating soil
iii. Poisoning plants
Used engine
oil dumped on land reduces soil productivity. Improperly disposed used oil ends
up in landfills, sewers, backyards, or storm drains where soil, groundwater and
drinking water may become contaminated.
2.2.5
Physical and Chemical Properties of used Engine Oil
Standard
chemical and physical tests are used to evaluate the properties of the oil and
the extent of the contaminants in the used automotive oils. These tests involve
the following measurements:
(1)
Viscosity: viscosity testing can indicate the presence of contamination in used
lubricating oil. The oxidation and polymerization products that were dissolved
and suspended in the oil cause the increase of oil viscosity. While a decrease
in the viscosity of lubricating oil indicates the fuel contamination.
(2) Pour
point: pour point is the lowest temperature at which the oil will flow. Low
pour point indicates good lubricating oil.
(3) Flash
point: flash point is the lowest temperature at which the vapours in air will
burn momentarily if ignited by flame or spark. A decrease in flash point
indicates contamination by dilution of lubricating oils with unburned fuel.
Increasing of flash point indicates evaporation of the light components from
the lubricating oil.
(4) Acidity
or neutralization number: this is a measure of the amount of alkali required to
neutralize one gram of the oil. An increase in acid number indicates the extent
in oxidation of lubricating oil.
(5) Ash
content: the remaining solid ash, when the oil is completely burned, is a
measure of oil purity and indicates contamination with metals.
(6) Carbon
or coking test: this evaluates the solid residue obtained when the oil is
heated to complete vaporization and it refers to the amount of deposit formed.
(7) Water
content: this test is done by distillation and indicates the amount of water
emulsified in the oil.
(8) Fuel
contaminants: this test indicates the amount of fuel diluting in the
lubricating oil during operation (Awaja & Pavel, 2016).
2.2.6 Impacts
of used Lubricating Oil
The
contaminants in used oil have adverse environmental and health impacts. The
presence of degraded additives, contaminants, and by-products of degradation
render waste oils more toxic and harmful to health and environment than virgin
base oils. If put into storm water drains or sewers, they can affect waterways
and coastal waters. When dumped in soil or sent to landfill, they can migrate
into ground and surface waters though numerous land treatment processes. In
addition, uncontrolled used oils are a threat to plant and animal life, which
can further result in economic losses, i.e. recreation and fishing industries.
For example, used oil from internal combustion engines generally accumulates a
variety of contaminants which increase the oil’s toxicity (Diphare et al.,
2013).
Improper use
of old oil for a variety of traditional applications results in a variety of
environmental and health consequences. Table 2 shows some of the local
applications of altered oil, as well as their direct and indirect negative
impacts (Nwachukwu et al., 2012).
According to
the EPA, one quart of used oil can render one million gallons of water unfit to
drink. When used oil enters surface water, oil films will block sunlight,
impair aquatic lives.
These
contaminants not only cause issues when they are released into the environment
due to poor management, but they can also obstruct used oil recycling. They are
also discovered to be concentrated in the waste streams of reprocessing or
re-refining operations at times, which can lead to additional disposal issues
(Yang, 2008).
2.3 Used
Oil Recycling and Reuse
There have
been numerous efforts to recycle spent lubricating oils because they are such a
valuable resource. Water is removed from used lubricating oil in a dehydration
process at "re-refineries." Vacuum distillation separates impurities
from spent oil, such as industrial fuel, and the oil is captured. This produces
a large amount of oil-filled trash, oil additives and byproducts.
remove other contaminants, the extracted lubricating oil is
refined. The oil is refined and then divided into three viscosities for various
applications.
For the past four decades, lubricating oil has being reused.
In the year 1930, the concept of repurposing leftover lubricating oil was
proposed. Used
lubricating oils were burned to generate energy at first, and then these oils
were treated and re-blended into engine oils. The disposal and recycling of
waste oils has become extremely significant as a result of the growing need for
environmental protection and stricter environmental legislation. The three
basic ways for reusing spent lubricating lubricants are as follows:
incineration, reprocessing, and re-refining.
Incineration
or combustion of used oil can be used to eliminate it thermally. Only a small
amount of used oil is currently burnt due to the economic benefits of recycling
it. Incinerated used oil typically contains high levels of harmful pollutants,
making recycling impractical or dangerous (Diphare et al., 2013).
Reprocessing
technology allows waste oil to be treated and burned in order to recover
energy. It entails removing water and particles from old oil so that it can be
burned as a fuel to create heat or power industrial processes. Because the oil
may only be reused once, this type of recycling is not as preferable as systems
that reuse the material.
Nonetheless,
it is one of the economically attractive ways of managing used oil
providing valuable energy i.e. about
the same as provided by normal heating oil (Chia-Yu, 2008). A litre of used oil
re-processed as fuel contains about 8,000 Kcal of energy, which is enough
energy to light a 100 W bulb for one day or to operate a 1000W electric heater
for 2 hrs. (Nwachukwu et al., 2012). Compared to direct burning, the major
advantage from reprocessing used oil is that it improves the burning quality of
used oil by removing/reducing some contaminants (Isah, 2013) Used oil can also
be re-refined back into base lube oil. Lube oil is a premium substance that can
be re-refined and reused again and again. In general, water and dissolved low
boiling point organic are removed by atmospheric or moderate vacuum
distillation. Lube oil is then recovered using different treatments and/ or
unit operations. Light end by-products are commonly used for plant combustion
fuels. After further enhanced treatment, the diesel and gas oil fractions can
be recovered as high-quality by-products. The asphalt industry can employ the
residual streams from distillation as an asphalt flux to make roofing asphalt,
paving asphalt, insulating materials, and other asphalt-based goods. Re-
refining involves treating used oil to remove impurities so that it can be used
as a base stock for new lubricating oil. Rerefining prolongs the life of the
oil resource indefinitely. This form of recycling is the preferred option
because it closes the recycling loop by reusing the oil to make the same
product that it was when it started out, and therefore uses less energy and
less virgin oil (Diphare et al., 2013)
2.3.1
Importance of Used Oil Recycling and Reuse
Used oil is
unquestionably an important energy source. Oil does not degrade with use; it
simply becomes dirty. Utilized oil can be refined into basic lube oil, recycled
into fuel oil, or used as a feedstock for the production of petroleum-based
products or other commercially valuable products using a variety of ways. Some
facts about conserving resources through correct treatment of old oil are
available. Refining old oil uses about a third of the energy required to refine
crude oil to lubricant quality, and one gallon of re-refined lubricating oil
yields the same 2.5 quarts of lubricant oil as 42 gallons of crude oil. As a
result, collecting and recycling used oil not only preserves our environment
from pollution, but it also saves a valuable resource.
Recycling
old oil effectively saves a valuable, non-renewable resource from the standpoint
of energy conservation. Only one barrel of crude oil is converted into virgin
lube stock for every 70 barrels of crude oil produced. Many oil corporations
invest billions of dollars in the exploration, recovery, and refinement of
crude oil into high-quality lubricant oil.used oil generated by consumers can
be recycled into valuable items like pure lubricating oil over and over again,
time and money can be saved significantly. Our natural resources will be
preserved, which is even more vital. Because of the huge quantities produced
globally, the possibility for direct re-use, reprocessing, and regeneration,
and the negative consequences on the environment if not properly managed,
treated, or disposed of, the management of spent oil is extremely significant.
Recycling used lubricants could have both environmental and financial benefits
(Yang, 2008).
2.4 RECOVERY
METHODS
The need to treat used engine oil for possible reuse has
arisen due to concern for the environment, scarcity, price stability, and increasing
dependence on this product for many industrial applications. Various methods of
recovering used oil include;
· Solvent Extraction
· Acid/clay treatment method,
· Vacuum Distillation,
· Membrane technology,
· Acetic Acid Treatment
· Formic Acid Treatment
The
characteristics of the fresh, used, and treated oil are tested for specific
gravity, viscosity index, flash point, pour point and concentrations of heavy
metals (aluminum, iron, and lead).
2.4.1
SOLVENT EXTRACTION METHODS
Solvent extraction has been used to recycle spent oil
but has its own disadvantages. The oil produced from this process caused huge
loss of solvent, and requires highly skilled operating maintenance. In
addition, extraction is conducted at higher pressures (greater than 10 atm.)
therefore requires high pressure sealing systems which makes solvent extraction
plants expensive to construct (Hopmans, 2014). Later propane extraction was
invented. Propane is capable of
dissolving waxy/paraffinic material and intermediately dissolved oxygenated
material (www.astm.org.,n.d.). Materials like asphaltenes which contain heavy
aromatic compounds are not soluble in the liquid propane. These properties tend
to make propane ideal for recycling the waste/used engine oil, but there are
many other issues that have to be considered such as propane is hazardous and
very flammable therefore it was regarded as a hazardous process (Hamawand,2015).
2.4.3
MEMBRANE TECHNOLOGY
Another method used for regeneration lubricating oils
was membrane technology. Three types of polymer fiber membranes [polyether
sulphone (PES), polyvinylidene fluoride PVDF), and polyacrylonitrile (PAN)]
were used for recycling the used/waste engine oils. This process is carried out at 0.1 MPa
pressure and 40°C (Martins, 2017) and is a continuous operation which removes
metal particles or dusts from used/waste engine oil and also improves the
recovered oils liquidity as well as flash point. Despite the above-mentioned
advantages, the expensive membranes may get damaged and fouled by large
particles (Henry, 2015).
2.4.4 ACID
TREATMENT PROCESS
Acid treatment is one of the popular treatment methods for
re-refining used oil. It involves the use of acetic acid or formic acid
respectively in the treatment of waste oil. The advantage of using the acetic
acid is that it does not react or only reacts slightly with base oils. The
recycling process takes place at room temperature or at most 40◦C. It has been shown that base oils
and oils’ additives are slightly affected by the acetic acid.
This process
of recycling of used engine oil does not emit poisonous gases like sulfur
dioxide to the atmosphere. In addition, glacial acetic acid has less of a
negative impact on the processing equipment compared with sulfuric acid used in
acid clay treatment process or other treatment processes.
Fig.
2.1 Block diagram of recycling of used engine oil
CHAPTER THREE
MATERIALS AND METHODS
3.1Materials
3.1.1
Experimental Materials
(i) Used
Engine Oil
(ii) Fresh
Engine Oil
3.1.2 Equipment Used
1. Thermometer
2. Solvent
extractor
3. Round
bottom flask
4. Measuring
cylinder
5. Desiccator
6. Clock
7. Beakers
8. Hot plate
9. Decanter
3.1.3 Reagents
(i)
Acetic Acid
(ii) Distilled water
3.2
Methods
3.2.1
Material Preparation
The
used engine oil was collected from various mechanic workshops within the worldbank
Housing Estate New Owerri Imo State. The used engine oil collected were used by
private and commercial vehicles. All the chemical reagents and solvents used in
this project work were of analytical grade, and were used without further
purifications.
The regeneration of the used engine oil experiment was carried out at the New Concept Laboratory Obinze. The characterization of the engine oil was done in the laboratory
3.2.2
Experimental Procedures
i.
Sedimentation
/Decantation
At the end of the acid treatment step, the acidic oil
will be allowed to settle 24 hours to form sediment at the bottom of the
beaker. After this period, the acidic-oil will
properly sediment and decanted into another 500 ml beaker using piece of
cloth while the residue (acidic sludge) at the bottom of the beaker is
discarded.
ii. Bleaching
The acidic oil in the beaker is subjected to
bleaching. The oil is placed on a regulator hot plate and the temperature was
maintained at a temperature of 110°C. 6 wt% of activated bleaching earth
is introduced into the oil and the
mixture is continuously stirred for 15 minutes. At the end of the bleaching
step, the bleached oil is neutralized.
iii. Neutralization
The bleached oil is neutralized to adjust the pH of
the oil to neutrality. At this step, 4 wt% of the oil of sodium hydroxide was
introduced into the bleached oil by taken into consideration the pH of the
bleached oil at a given point in time. The bleached oil was neutralized with a
continuous manual stirring for 10 minutes. At the end of the bleaching and
neutralization steps, the oil is allowed to sediment in the beaker for 24 hours
and is decanted into the beaker, while the residue at the bottom of beaker is
discarded.
iv. Filtration
The sediment oil is finally filtered using a filter cloth and the filtrate is collected in a filtration flask and it is observed to be clear while, the residue (filter cake) will be discarded.
CHAPTER
FOUR
RESULTS
AND DISCUSSION
4.1 RESULTS
This
chapter contains all the results obtained from the experiment carried out in
the course of this study.
The
results of the research which investigates the recycling of used Engine oil and
compared with the fresh Engine oil sample using acetic and formic acid
treatment have been carefully detailed in Table I. The Table I also includes
the results of the various quality tests (appearance, viscosities at 55°C, flash point, specific gravity and pour point)
performed using ASTM methods on the lubricating oil products.
Table
4.1: Summary of Analysis of Results
|
Tests |
Units |
Test
Methods |
Specifications |
Fresh
Oil |
Used
Oil |
Acetic
Acid Clay Treatment Method |
Formic
Acid Clay Treatment Method |
|
Appearance |
Visual |
Bright
and Clear |
Dark |
Dark |
Dark |
Dark |
Dark |
|
Flash
Point |
(⁰C) |
ASTM-D0092 |
Min.200 |
220 |
170 |
200 |
200 |
|
Viscosity, 55⁰C |
(mPa.s) |
ASTM-D0445 |
As
Reported |
604-610 |
627 |
607.15 |
606.65 |
|
|
(Cst
mm²/s) |
ASTM-D0445 |
12.5-16.3 |
13.70 |
11.42 |
13.95 |
14.16 |
|
|
(Cst
mm²/s) |
Calculated |
|
134 |
125 |
139 |
138 |
|
|
(Mg
KOH/g) |
ISO
3771 |
7.00-12 |
|
11.66 |
7.23 |
7.67 |
|
Specific
Gravity |
Kg/m^3 |
ASTM-D1298 |
|
0.881 |
0.8855 |
0.855 |
0.877 |
|
Pour
Point |
⁰C |
ASTM-D1298 |
|
4 |
13 |
5 |
6 |
Fig. 4.1: Effects of recycling used engine oil on its specific gravity
Fig. 4.2: Effects of the recycling of used engine oil on its viscosity at 55°C
Fig. 4.3: Effects of the recycling of used engine oil on its pour point
DISCUSSION
4.2 Discussion
The discussion of the results obtained from the recycling experiment was done with emphasis laid on the various basic properties of the oil which includes the appearance, flashpoint, viscosity, specific gravity, density and pour point.
i. Appearance: This indicates the brightness and clarity of petroleum products. The results of the appearance (Table 1) of the fresh lube oil, used lube oil and the treated lube oil show that the fresh oil have a clear and bright color while the used and the treated lube oil have a dark appearance. The dark appearance of the used lube oil and those from the treated methods were due to their combustion and oxidation at high temperature by the combustion engine for a very long time.
ii. Flash Point: The flash point of lubricating oil is the lowest temperature where it will evaporate enough fluid or vapor to form a combustible concentration of gas with air that can be ignited spontaneously by a specified flame. In summary, flash point indicates how easily lubricating oil may burn and ignite (Udonne, 2016). The result of the flash point of the fresh lube oil, used lube oil and the treated lube oil above shows that, there was a decrease in the flashpoint for the used lubricating oil which is below the minimum specification of flashpoint for SAE-40 lube oils. The decrease in the flashpoint of the used lube oil was due to contamination of very volatile component. On treating, the volatile components were extracted from the used lube oil. Thereby increasing the flash point above the minimum specification of SAE-40 except the Citric acid clay treatment method. From the experiment carried out the flash point using acetic acid and formic acid treatment is 200°C.
iii. Viscosity at 55°C: The results (Table 1) of the Kinematic Viscosities (KV) at 40°C using the ASTM-D 0092 Method shows that the used oil sample with Kinematic Viscosity (KV) of 600mPa.s and using acetic and formic acid we have 606.65mPa.s and 607.15mpa.s. The plot of kinematic viscosities of each of the recycled lube oils (Fig. 2) reveals that they all fell within the required specification range (Brinkman et al., 1981). This shows that at 55°C, the recycled methods still retained the viscosity specification range (604- 610mPa.s) for SAE 50 oils.
iv.
Specific
gravity/density:
The
specific gravity of contaminated or used lube oil could be lower or higher than
that of its fresh lube oil depending on the type of contaminates in the used
oil. If the used lube oil is contaminated by dilution of light oil/volatile
component or contaminated due to fuel dilution and/or water originating from
fuel combustion in the engine and accidental contamination by rain, its
specific gravity will be lower than that of its fresh lube oil (Udonne, 2016).
But, on the other hand when the specific gravity of the used oil is greater
than that of the fresh lube oil, then the lube oil may have been contaminated
by heavy oil or component with a higher carbon atom. The results for the fresh
and used lubricating oils are 0.881 and 0.8855, respectively. This shows that
the used lube oil may have been contaminated by dilution of light oil. It is
also very likely that some of the heavier components of the lube oil had broken
down to lighter fractions at the high operating engine temperature. After
undergoing different treatments by the various methods, the volatile components
were extracted which consequently increased the specific density of the
recycled oil obtained using acetic acid is 0.855 and that
of formic acid is 0.877. The plots are shown in Fig. 4.1
v.
Pour Point: Pour point is the lowest temperature at which the oil will
flow. Low pour point indicates good lubricating oil. From the experiment
carried out the
pour
point of engine oil using acetic and formic acid is 5°C
and 6°C respectively
CHAPTER FIVE
CONCLUSION AND
RECOMMENDATION
5.1 CONCLUSION
This research has shown that used lubricating oil can be effectively recycled using acetic acid treatment and formic acid. The results show that there were contaminants of light oil/ a very volatile components present in the used oil and it was shown that the two methods used removed the volatile contaminants from the used lubricating oil and removed the oil to a quality essentially equivalent to fresh lube oils. Furthermore, this new process of recycling used engine oil does not emit poisonous gases like sulfur dioxide to the atmosphere. It is contemplated that, it will cost less to buy the used oil and it has been proved to yield about 80% while the yield from crude oil is between 5 to 10% (udonne,2015). The recycling of used oil will greatly decrease the rate at which it has polluted the environment and it will also reduce the demand for lubricant rich crude which is a dwindling and finite resource. In addition, organic acid has less of a negative impact on the processing equipment compared with inorganic acid like sulfuric acid. Lower number of additives may be required for the base oil recycled by acetic acid method due its low reactivity with the used oil. Further research is required in order to take this process to the commercial stage.
5.2 RECOMMENDATIONS
The
following strategies are recommended for follow up whilst working on this
project:
i. The general public should be sensitized on the danger of the used Engine oil on human health, thus the process of recycling used oil should be encouraged in order to save our environment from indiscriminate disposal of the used lube oil. In addition, Further research is required in order to take this process to the commercial stage.
ii.
As
a chemical engineer, I will strongly recommend that the acetic acid treatment
method should be encouraged because it is less expensive to operate and it is
safe for both equipment’s and labour. Also, to achieve a better result, the
regenerated spent engine oil should be heated to a higher temperature before
the adsorption process.
iii.
However,
while few variables have been studied in this research, there are many others
that need thorough investigation such as pressure, settling time, mixing speed
& time and type & size of adsorbent which have significant effects on
the recycled oil qualities. In addition, the aforementioned aspects are important
concerning the general characteristics of the treatment and recycling of used
oil.
iv.
Also,
a detailed cost benefit analysis evaluation should be made that will likens the
potential benefits of used oil recycling with the expected costs of
construction and erection of the scaled-up plant.
v. Further character testing may also be executed to evaluate oxidation stability, thermal stability and foaming character of the recycled oil. Possible practical application of the recovered oil in a real engine system should be experimented on.
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APPENDICES
Fig. 2.1 Block diagram of recycling of used engine oil
Fig 4.2 Effects of recycling used
engine oil on its specific gravity
Fig. 4.3: Effects of used engine
oil on its viscosity at 55◦C
Fig. 4.4: Effects of used engine
oil on its pour point
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