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CHAPTER 1

INTRODUCTION

1.1 Background of Study

Over the years, more than 70% of used engine oil (commonly referred to as

condemned or spent oil) is most often disposed as waste in Nigeria after

automobile lubrication. This act brings about pollution of the environment.

However, it has been found to be a potential alternative raw material for ink

production. Its utilization in this area will minimize its wastage and reduce

pollution.

Waste engine oil is a highly hazardous pollutant that requires responsible

management. Waste engine oil may cause damage to the environment when

dumped into the ground or into water streams including sewers. 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.

Used engine oil contains resin, organic acids and polymers. These substances

can be precipitated as varnish and asphaltic resin known as sludge. This can be

achieved by treating the oil with concentrated sulphuric acid, sodium

hydroxide and other additives to yield crude base oil and sludge as byproduct.

The sludge produced contains polymeric materials such as asphaltenes,

carboids, carbenes and petroleum resins which are responsible for the black

colour of engine oil.

Charcoal has been often used as fuel for cooking, the activated one is used in

air and water purification, treatment of sewage, as the filter unit in respirators

and gas masks, for the purification of gas and compressed air through filters

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such as in the life support in space suits. It is also used for the recovery of gold

from cyanide solutions, as a metal extraction method and for its use in the

cleanup of chemical spills. However, it can now be used as an alternative

material for ink production in place of carbon black which has since been used

in the production of black ink.

Printing of one form or another has been with us for centuries and whilst the

technologies of both the printing process and the ink formulations have

changed considerably, the main functions of decoration and information

remain. As new technologies are evolving, the printing industry undergoes

rapid development in the transmission of information within the society. It can

then be said that printing is an important tool for technology advancement

(Richard, 2008).

Ink is one of the most important materials used in the printing industry. There

are so many definitions of ink. To a layman, it can be defined as coloured

substance used for writing, printing and decoration purposes. But in a more

advanced context, ink is defined as a mixture of colouring matter dispersed in

a vehicle or carrier which forms a fluid or paste which can be imparted on a

substrate and dried.

Ink can be defined as a mixture of intimately ground pigment dispersed or

dissolved in a vehicle, which can be printed on a substrate and dried. Printing

ink contains colorants usually pigments which gives the image a contrast

against the background and the vehicle which binds the pigment to the

substrate and thus provides adhesion.

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1.2 Aims and Objectives

To produce a neutral and dehydrated sludge from used engine oil.

To determine the effect of temperature on sludge yield.

To use the sludge and generate a formulation for black printing ink.

To select the best formulation for black printing ink production.

1.3 Scope of Study

The project work covers the following areas:

Desludging of engine oil to yield resinous sludge and crude base oil.

Determination of the optimum temperature and development of the

sludge yield models.

Production of black printing Ink.

Quality test on the produced ink to ensure that it meets market

requirements.

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CHAPTER 2

LITERATURE REVIEW

2.1 Nature of Inks

Inks are coloured materials used for the purpose of writing, printing, and

decoration (Kirk, 1981). Ink is a liquid or a paste like (semi- liquid) material that

is used for drawing, writing, and printing either text or graphics (Lichtenberger,

2004). Ink is a colloidal system that is typically comprised of colorant, vehicle,

solvent, and additives (Lichtenberger, 2004). Ink can be defined as a mixture of

intimately ground pigment dispersed or dissolved in a vehicle, which can be

printed on a substrate and dried (Taylor 2007). They are materials designed to

have decorative, protective and communicative function (Othmer 1981). It is

applied on different surfaces ranging from aluminum cans and plastic bottles

through to paper (Taylor 2007).

According to Wansbrough (2007, p.1), printing inks are made of four basic components:

Pigments: They colour the ink and make it opaque.

Resins: They bind the ink together into a film and bind it to the printed

surface.

Solvents: They make the ink flow so that it can be transferred to the

printing surface.

Additives: They alter the physical properties of the ink to suit different

situations.

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2.2 The History of Ink Production

Writing inks were first manufactured in both ancient Egypt and China in about

2500BC. These inks were composed of soot bound together with gums. This

paste was formed into rods and dried, then mixed with water immediately

before use (Wansbrough 2007).

Printing was invented by the Chinese about 3000 years later (Taylor, 2007).

They used a mixture of coloured earth, soot and plant matter for pigments,

again mixed with gums for a binder. By 1440, when Johannes Guttenberg

invented the first printing press with moveable type, ink was made of soot

bound with either linseed oil or varnish - similar materials to those used for

black inks today. Coloured inks were introduced in 1772 and drying agents

were first used in the nineteenth century.

Today's printing inks are composed of a pigment (one of which is carbon black,

which is not much different from the soot used in 2500BC), a binder (an oil,

resin or varnish of some kind), a solvent and various additives such as drying

and chelating agents. The exact recipe for a given ink depends on the type of

surface that it will be printing on and the printing method that will be used

(Taylor 2007). Inks have been designed to print on a wide range of surfaces

from metals, plastics and fabrics through to papers. The various printing

methods are all similar, in that the ink is applied to a plate / cylinder and this is

applied to the surface to be printed. (Wansbrough 2007) However, the plate /

cylinder can be made of metal or rubber, and the image can be raised up

above the surface of the plate, in the plane of the plate but chemically treated

to attract the ink, or etched into the plate and the excess ink scraped off.

Different inks are produced to suit these different conditions.

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2.3 Raw Materials and Components

As has already been stated, the raw materials for ink production are pigments,

binders, solvents and additives.

2.3.1 Pigments

The most obvious role of a pigment is to colour the ink. However, they can

also provide gloss, abrasiveness and resistance to attack by light, heat, solvents

etc. Pigments give the ink its characteristic colour and contribute to the opacity

and permanence of the ink. They are inorganic or organic in form (Bisset 1979)

e.g. Carbon black and charcoal (which is used for this work). Carbon black is the

pigment that has since been used for the manufacture of printing inks but in

this study, charcoal is identified as an alternative. Special pigments known as

extenders and opacifiers are also used. Extenders are transparent pigments

which make the colours of other pigments appear less intense, while opacifiers

are white pigments which make the paint opaque so that the surface below

the paint cannot be seen. The process of forming pigments all rely on the

thermal decomposition or incomplete combustion of hydrocarbons such has

fuel oil and natural gas. Pigment selection is based on their wettability and

dispersion characteristics in various solvent and resin (Taylor 2007). Some

common pigments used in the manufacture of printing inks are given in the

table below.

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Table 2.1 Pigments used in Ink Production

Source: Printing Ink Manual (Bisset 1979)

Fig 2.1 Structure of some pigments used in ink production

Class Examples

Inorganic white (opacifiers) Titanium dioxide, zinc oxide

Extenders Calcium Carbonate, Talc- mixed oxide of

aluminium,magnesium,silica and calcium

Inorganic Black Carbon Black

OrganIc red Lithol, Toluidine derivative

Organic orange Pyrazolone, Dinitroaniline

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2.3.2 Resins

Resin is a non-crystalline solid material or liquid of relatively high molecular

weight and viscosity. Resins are primarily binders - they bind the other

ingredients of the ink together so that it forms a film and they bind the ink to

the paper.(Domo-Spiff 2009) They also contribute to such properties as gloss,

hardness, adhesion, flexibility and resistance to heat, chemicals and water.

Resins are divided into the following categories.

Natural Resin: This includes those obtained from pine trees which can be

separated into turpentine oil or colophony. Another example is asphalt which

is a residue when crude oil or coal tar is distilled. They are dark and only be

used for black inks.

Semi Synthetic: This includes alkyd esters, polyesters made of phtalic acid

esters and glycerol which are modified with some fatty acid. It also includes

chemically modified cellulose such as nitrated cellulose, ethyl cellulose, and

sodium carboxyl methyl cellulose etc. (Nwanta 2005).

Synthetic Resin: They are virtually innumerable and include acrylic, polyvinyl

acetate polyvinyl alcohol, and polyamide resin. In this work only asphaltic resin

gotten from used engine oil is used.

Many different resins are used, and typically more than one resin is used in a

given ink. According to Taylor (2007, p.3), the most commonly used resins are

listed below:

Acrylics

Ketones

Alkyds

Maleics

Cellulose derivatives

Formaldehydes

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Rubber resins

Phenolics

2.3.3 Vehicle

This is the liquid ingredient in to which the pigment and other ingredient are

mixed. The vehicle acts as a carrier for the pigment and as binder to affix the

pigment to the printed surface and is also responsible for gloss and hardness of

the dried ink film.

To a great extent it determines the viscosity, consistency, and fluidity of the ink

(Domo-spiff 2009). Some of the popular examples are linseed oil, diesel oil,

resin oil, alcohol etc. Because every pigment-vehicle formulation behaves

differently, the addition of the ingredients is carefully considered.

2.3.4 Solvents

Solvents are used to keep the ink liquid from when it is applied to the printing

plate or cylinder until when it has been transferred to the surface to be

printed. At this point the solvent must separate from the body of the ink to

allow the image to dry and bind to the surface. Some printing processes (e.g.

the gravure and flexographic processes) require a solvent that evaporates

rapidly. These use volatile solvents (i.e. those with boiling points below 120°C)

such as methylated spirits, ethyl acetate, isopropanol, n-propyl acetate.

2.3.5 Additives

Many different types of additives are used to alter the final properties of the

ink. The most common types of additives and their respective functions are

listed below.

Plasticiser: It enhances the flexibility of the printed film. Eg dibutyl phthalate.

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Wax: It promotes rub resistance. E.g. Carnauba - an exudate from the leaves

of Copernicia prunifera. It consists of esters of hydroxylated unsaturated fatty

acids with at least twelve carbon atoms in the acid chain (Apps 1963).

Drier: Catalyses the oxidation reaction of inks which dry by oxidation. E.g. salts

or soaps of cobalt, manganese or zirconium.

Chelating agent: Increases the viscosity of the ink (aluminium chelate) and

promotes adhesion (titanium chelate)

Antioxidant: Delays the onset of oxidation polymerisation by reacting with free

radicals formed during the autooxidation thus preventing them from reacting

further. E.g. Eugenol.(Apps 1963)

Surfactants: Improves wetting of either the pigment or the substrate

Alkali: It controls the viscosity / solubility of acrylic resins in water based inks

e.g.HOCH2CH2NH2 (monoethanolamine).

Defoamer: It reduces the surface tension in water based inks, meaning that

stable bubbles cannot exit hydrocarbon emulsions.

2.4 The Manufacturing Process

Ink is manufactured in two stages: first varnish (a mixture of solvent, resins

and additives) is made and then pigments are mixed into it.

2.4.1 Varnish manufacture

Varnish is a clear liquid that solidifies as a thin film. It binds the pigment to the

printed surface, provides the printability of the ink and wets the pigment

particles. There are two main sorts of varnish: oleoresinous varnish (which

incorporates a drying oil such as linseed oil) and non-oleoresinous varnish.

Oleoresinous varnish is manufactured at much higher temperatures and in

much more rigorous conditions than non-oleoresinous varnish (Wansbrough

2007). The two manufacturing processes are discussed below.

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Oleoresinous Varnish Manufacture

These varnishes are typically manufactured in closed kettles where the oil and

solvent are heated to allow for rapid solutioning or transesterification

(Wansbrough 2007). The temperatures involved in the process will vary but

may range from 120°C to 260°C. Cooking times may range from a few minutes

to several hours. Temperature control is critical in the process. Rate of

temperature change, maximum temperature attained and cooking duration is

closely monitored. A condenser is usually used to prevent solvent loss.

Since these varnishes include a drying oil, atmospheric oxygen must be

excluded to prevent this from polymerising. For this reason cooks are often

done using a nitrogen blanket.

In the production of a typical oleoresinous ink varnish, drying oil, alkyd and

other solvents are added to the vessel under nitrogen prior to cooking. Hard

resins are then added when the correct temperature is attained. The cooking

process continues until the reactants are either totally consumed in the

transesterification process or achieve adequate solubility in the solvent (Taylor

2007). Additives such as the chelating agent are added after the batch cools

down. Finally, the varnish mixture is reheated to obtain targeted rheological

properties. The varnish produced is tested before sending to the storage tank.

Non-oleoresinous Varnish Manufacture

Varnishes of this type are usually simple resin solutions that do not require

high temperatures to effect a reaction. They are manufactured by breaking up

the resin particles and dissolving them in a solvent in either a cavitation or a

rotor / stator mixer. Cavitation mixers contain a saw tooth disc on a driven

shaft and are used to produce high viscosity resin solutions. They can operate

at variable speeds. Rotor / stator mixers operate at a fixed speed. Varnishes

produced in these mixers must be of lower viscosity than those produced in

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cavitation mixers because the agitation in the mixer is much less. Heat

sensitive resins cannot be used in a rotor / stator mixer because the high

friction within the mixer produces high temperatures (Bisset 1979).

2.4.2 Pigment Dispersal

Once the varnish (containing the solvent, resin and additives) has been

produced the pigment is mixed into it. At this point the pigment particles

clump together. These clumps must be broken up and the pigment dispersed

evenly through the resin. There are three main types of equipment used to do

this, and which is chosen depends on the tack (stickiness) and rheology of the

ink. The three equipment types are discussed below.(Wansbrough 2007)

Three Roll Mills

A three roll mill consists of a series of cambered rollers rotating in opposite

directions. The pigment particles are fed into a hopper above the two rear-

most rollers and are dispersed by the shear forces between the rollers. A

doctor blade is fitted to the front roller to remove the dispersed product. Roll

pressure, speed ratios and temperature must be carefully controlled to allow

reproducible dispersion. Each of the rolls is water cooled to reduce the

buildup of frictional heat.

Bead Mills

A bead mill consists of a cylindrical chamber filled with beads and surrounded

by a water jacket for cooling. Ink is pumped into the chamber and the beads

(known as the 'charge') set in motion by a series of spinning discs or pins

(Taylor 2007). The charge grinds the ink, breaking up the pigment clumps and

evenly dispersing the ink. The ink then flows out of the chamber through a

sieve and the charge remains behind to be re-used. According to Wansbrough

(2007 p.5) the bead size depends on the viscosity and rheology of the ink.

Typical bead sizes range from 1-2 mm for a high quality low viscosity product

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such as a gravure ink up to 4 mm for a medium viscosity paste or screen ink.

The beads can be made of zirconium oxide, glass or stainless steel. Certain

beads discolour certain inks, so it is important that each ink is tested with the

different beads before grinding to ensure that appropriate beads are used.

Cavitation Mixers

The use of cavitation mixers for the production of resin solutions has already

been discussed.

However, mixers of this type are also very efficient at dispersing certain

pigments, notably titanium dioxide, and allowing predispersion of a number of

others. In a highly viscous ink system a cavitation mixer may be insufficient to

ensure even dispersal and as a consequence an additional sweeper blade may

be added.

2.5 Engine Oil and Its Applications

Engine oil (sometimes called motor oil) is the oil used in lubricating various

internal combustion engines of road vehicles such as cars and motorcycles,

heavy duty vehicles such as buses, lorries, trailers, trucks and non road

vehicles such as go-carts, snow mobiles, boats, lawn mowers, large agricultural

and construction equipments, trains aircrafts and electrical generators. Its

main role is to clean, inhibit corrosion and cool the engine by carrying away

excessive heat generated by the moving parts of the engine (Domo-Spiff 2009).

In engines, the moving parts make contact with each other causing friction

which consumes the useful power by converting the energy to heat. This also

causes wears and tears in those parts and leads to lower efficiency and may in

some cases lead to total failure of the engine.

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Consequently, engine oil creates a separating film between the surfaces of the

adjacent moving parts to minimize direct contact between them, thereby

decreasing friction and production of excessive heat. One of the main

properties of the oil that enables it to be effective in lubrication is its viscosity.

This is the resistance to flow of the oil. It may be high enough to create a film

but low enough to flow around the engine parts satisfactorily.

2.5.1 Degradation of Engine Oil

The majority of motor oils is derived from petroleum and mostly consists of

hydrocarbons, organic compounds containing carbon and hydrogen. Most of

them are made from heavier petroleum base stock derived from crude oil, with

additives to improve certain properties.

During the operation of the engine, the oil breaks down and the major

properties of the oil change due to oxidation, deposits, thermal degradation,

corrosion, shearing and contamination. This reduces its ability to carry out its

primary function of reducing friction, heat dissipation, corrosion prevention

and cleaning.

Oxidation is the most important form of chemical breakdown of engine oil and

its additives. The chemicals in the motor oil are continuously reacting with

oxygen inside the engine. The byproducts of combustion produce very acidic

compounds inside the engine. These acidic compounds causes the corrosion of

the internal engine components, deposits and mainly changes in the oil

viscosity. Other substances like sludge, vanish and other insoluble combustion

products are solely responsible in the degradation of the engine over a period

of time due to oil break down. The products of combustion are less stable than

the original base hydrocarbon molecular structure and as they continue to be

stacked by these acidic compounds, vanish and sludge are produced.

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Fig 2.2 Processes in Hydrocarbon Oil Degradation

2.6 Chemical and Physical Properties of Engine Oil

Flash Point

The flash point of engine oil is the lowest temperature to which the oil must be

heated under specified conditions to give off sufficient vapor to form a mixture

with air that can be ignited spontaneously by a specified flame. The flash point

of engine oil is an indication of the oil’s contamination. A substantial indicator

of flash low flash point shows that the engine oil has been contaminated with

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gasoline. In the presence of 3.5% fuel or greater in used engine oils, the flash

point will potentially reduce to below 55 °C. The flash point is also an aid in

establishing the identity of a particular petroleum product. The flash point

increases with increasing molecular mass of the oil. Oxidation would result in

formation of volatile components which leads to decrease the flash point

(Lenoir 1975). For instance the flash point of the base oil (Ravenol, VSi SAE 5W-

40) is 232 °C because it is contains many different additives which contribute

to improving its flash point. (Hamawand et al 2013) In contrast, the flash point

of the measured used engine oil is 158 °C. This decrease in flash point is a

result of contamination with fuel and oxidation products (Lenoir 1975).

Kinematic Viscosity

Viscosity is a state function of temperature, pressure and density. There is an

inverse relationship between viscosity and temperature, when the

temperature of the engine oil decreases the viscosity increases and vice versa.

Viscosity testing can indicate the presence of contamination in used engine oil.

The oxidized and polymerized products dissolved and suspended in the oil may

cause an increase of the oil viscosity, while decreases in the viscosity of engine

oils indicate fuel contamination. (Diaz et al, 1996)

Specific Gravity

Specific gravity is the ratio of the mass of volume of substance to the mass of

the same volume of water and depends on two temperatures, at which the

mass of the sample and the water are measured. Specific gravity is influenced

by the chemical composition of the oil (Hamawand, Yusaf & Rafat, 2013). An

increase in the amount of aromatic compounds in the oil results in an increase

in the specific gravity, while an increase in the saturated compounds results in

a decrease in the specific gravity. An approximate correlation exists between

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the specific gravity, sulfur content, carbon residues, viscosity and nitrogen

content (Forsthoffer & Lube, 2011). Used engine oil’s specific gravity increases

with the presence of increasing amounts of solids in the used engine oil. One

percent of weight of solids in the sample can raise the specific gravity by 0.007

(Forsthoffer & Lube, 2011). Used engine oil is contaminated with oxidized and

condensed products rich in carbon. The high value of specific gravity of used

engine oil is due to the presence of oxidation products, metals and

contamination.

Refractive Index

Refractive index (RI) is the ratio of the light velocity in vacuum to the light

velocity in substances at a specific temperature. The measurement of the

refractive index is very simple, and requires small quantities of the samples.

The refractive index can be used to provide valuable information about the

composition of engine oils. Low values of refractive index indicate the presence

of paraffin material while high values indicate the presence of aromatic

compounds. It is also used to estimate other physical prosperities such as

molecular mass (Riazi & Roomi, 2001). This is due to the presence of additives

like polymers, polar organic compound, organic compound, different metals,

copolymers of olefins and hydrogenated diene styrene copolymers (Riazi &

Roomi, 2001). These components increase the molecular mass of the base oil

and consequently its refractive. The addition of acid reduces the RI.

Water and Sediments

Water is generally referred to as a chemical contamination when suspended in

engine oils. Water contamination of engine oil affects the oil quality, condition

and wear of engines in service. The water content in engine oil is governed by

the oil composition, physicochemical properties, production technology and

conditions of storage and use. Water created in engine oil is a result of:

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absorbing moisture directly from the air (oil is hygroscopic), condensation

(humid air entering oil compartments), heat exchanger (corroded or leaky heat

exchangers), combustion (fuel combustion forms water which may enter the

lubricant oil through worn rings), oxidation (chemical reaction) and

neutralization (when alkalinity improvers neutralize acids formed during

combustion), and free water entry (during oil changes). Water can prompt a

host of chemical reactions such as hydrolysis of compounds and atomic species

including oil additives base stock and suspended contaminants. In combination

with oxygen, heat and metal catalyst, water is known to promote the oxidation

and the formation of free radicals and peroxide compounds. Water attacks

additives such as oxidation inhibitors, rust inhibitor, viscosity improver and the

oil's base stock forming sludge. The water and sediment content of engine oil is

significant because it can cause corrosion of equipment and problems in

processing (Kishore, 2007).

Carbon Residue The amount of carbonaceous residue remaining after thermal decomposition

of engine oil in a limited amount of air is also called coke or carbon forming

tendency. The test for carbon residue can be used at the same time to evaluate

the carbonaceous depositing characteristics of engine oils used in internal

combustion engines. The carbon residue value of engine oil is regarded as

indicative of the amount of carbonaceous deposits engine oil would form in

the combustion chamber of an engine. It is now considered to be of doubtful

significance due to the presence of additives in many oils. For example, an ash-

forming detergent additive can increase the carbon residue value of engine oil

yet will generally reduce its tendency to form deposits (Kishore, 2007). This

may be due to the complex reactions of the oil’s components with sulfuric acid

which may increase the sulfur content of the oil. A more precise relationship

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between carbon residue and hydrogen content, (H=C) atomic ratio, nitrogen

and sulfur content have been shown to exist.

Total Acid Number (TAN)

Total Acid number (TAN) is the weight (in milligrams) of potassium hydroxide

required to neutralize one gram of the materials in the oil that will react with

(KOH) under specific test conditions. The usual major components of such

materials are organic acids, soaps of heavy metals. As engine oils are subjected

to elevated temperatures, the process of oxidation occurs. Oxidation leads to

the formation of organic acids in the engine oil. Total acid number (TAN) has

been considered to be an important indicator for engine oil quality, specifically

in terms of defining oxidation states. The presence of oxygen, in most engine

oils environments, and hydrocarbons which make up the base oil lead to some

reactions. This reaction may lead to the formation of carbonyl-containing

products (primary oxidation products), subsequently these undergo further

oxidation to produce carboxylic acids (secondary products) which results in an

increase in the TAN value (Fox, Pawlak & Picken, 1991). In addition, with time

and elevated temperature, the oxidation products formed then polymerize

leading to precipitation of sludge which decreases the efficiency of engine oil

and causes excessive wear.

This is due to the presence of organic, inorganic, heavy metal salts, ammonia

slots, resin, water and corrosive materials which result from the oxidation

process that occurred at elevated temperatures in the engine.

Metallic Content Metals are regarded as heteroatoms found in engine oil mixtures. The amounts

of metals are in range of a few hundred to thousands of ppm and their

amounts increase with an increase in the boiling points or decrease in the API

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gravity of the engine oil. Engine oils’ metallic constituents are associated with

heavy compounds and they mainly appear in the residues. Base and base

engine oils have very little metal content, which indicates their purity. Some

metals present in virgin oils in high concentrations are in the form of various

additives which improve the performance of the engine oil. Many others are

introduced in to the oils after using due to depletion of various additives,

engine bearings or bushings, and dilution of the engine oil with fuel containing

metal additives (Abou El Naga & Salem, 1984). According to Yusaf et al. (2013,

p.1035) Metals are found in used engine oil in two forms:

Metal Particulate Contamination

Metallic particulates enter the engine oil as a consequence of the breakdown

of oil-wetted surfaces due to ineffective lubrication, mechanical working,

abrasion erosion and/or corrosion. Metallic particles from deteriorating

component surfaces are generally hard and increase the wear rate as their

concentration in the oil increases.

Element (Metals)

Many oil constituents contain metallic elements that have been added to

enhance the oil’s efficiency. In general, metals in engine oils regarded as

contaminants that should be removed completely in order to produce suitable

base oil for producing new virgin oil Aucelio et al., 2007)

Copper (Cu) is introduced to engine oils after use from bearings, wearing and

valve guides. Engine oil coolers can also be contributing to copper content

along with some oil additives (Alder & West, 1972). Magnesium is normally

introduced into engine oil in an additive package.

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Magnesium is regarded as the most common wear metals in used engine oil

and is present in virgin oil in the form of magnesium phenates and magnesium

salicylates that behave as antioxidants at high temperatures (Hopp & Erdoel

Kohle, 1974).

Chromium presence in engine oil is normally associated with piston ring wear.

High levels can be caused by dirt coming through the air intake or broken rings.

Chromium may indicate excessive wear of chromed parts such as rings and

liners (Kahn, Peterson & Mannings, 1970).

The most common wear metal in a car's engine that is introduced into the

engine oil after a period of use is iron. Iron comes from many various places in

the engine such as liners, camshafts and crank shaft, pistons, gears, rings, and

oil pump. Iron concentration in engine oil depends on the bearing conditions

inside the engine. If a bearing fails, iron concentrations in used engine oil

increases. In the engine, the wear rises at a faster rate during the starting of

the engine.

Zinc is introduced to base oil in the form of additives package as anti-oxidant,

corrosion inhibitor, anti-wear, detergent and extreme pressure tolerance. Zinc

is introduced in to base oil as additives, such as:

Zinc diethyldithiophosphate (ZDDP), which functions as an oxidation

inhibitor that increases the oxidation resistance of the oil.

Zinc dithiophosphates, this is not only acts as an anti-oxidant, but also

acts as a wear inhibitor and protects the engine metals against

corrosion.

Zinc dialkyldithiocarbamates, this compound is mainly used as anti-

oxidants but it is also has extreme pressure activity.

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2.7 Oxidation Process in Internal Combustion Engines

Oxidation of engine oil inside the engine is related to the availability of oxygen

and in-cylinder pressure and temperature (Yusaf, 2011). It can be divided into

two types: oxidation at low and high temperatures. Oxidation of engine oil at

low temperatures leads to alkylhydroperoxides ROOH, dialkylperoxides ROOR,

alcohols ROH, aldehydes RCHO and ketones RR′C=O. In addition, cleavage of a

dihydroperoxide leads to diketones RCO(CH2)xCOR′, ketoaldehydes

RCO(CH2)xCHO, and hydroxyketones RCH(OH)–(CH2)xCOR′ (Owrang 2004). At

high temperatures (>120 °C) the engine oil oxidation process can be divided

into a primary and a secondary oxidation phase. In the primary oxidation phase

the initiation and propagation of the radical chain reaction are the same as

discussed under low-temperature conditions, but selectivity is reduced and

reaction rates increased. At high temperatures the cleavage of hydroperoxides

plays the most important role. Carboxylic acids (RCOOH) form, which

represents one of the principal products under these oxidation conditions. In a

subsequent step they can react with alcohols R′OH to form esters (RCOOR′).

The termination reaction proceeds through primary and secondary peroxy

radicals, but at temperatures above 120 °C these peroxy radicals also interact

in a non-terminating way to give primary and secondary alkoxy radicals

(Maduako 1996). The secondary oxidation phase happens at higher

temperatures where the viscosity of the bulk medium increases as a result of

the polycondensation of the difunctional oxygenated products formed in the

primary oxidation phase. Further polycondensation and polymerization

reactions of these high molecular weight intermediates lead to form sludge

(Owrang 2004). Reaction oxidation compounds in oil samples can be

determined qualitatively by obtaining their IR spectra in a Fourier Transform

Infrared Spectrometer (Thermo Scientific, Thermo Mattson Nicolet 300-FTIR).

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2.8 Charcoal and Industrial Applications

There are many uses of activated charcoal and these are found over a wide

range of industries. Several methods are used to activate the charcoal and

these all end with a similar result with the charcoal becoming very porous and

having a large surface area. This large surface area can be seen under a

microscope as something similar to multiple layers of holes, these act like a

sieve through which a various number of commodities that have impurities in

them are cleaned. These impurities may come from water, poisons, air, volatile

organic compounds, spill cleanups and numerous other things. This charcoal is

a product that is used in the process of filtration in many different industries

and everyday uses.

One of the many everyday uses of activated charcoal is in water purifiers. This

product helps to remove unwanted impurities from tap or drinking water with

the end result being clean water suitable for drinking and other household

uses. Activated charcoal is also used for the purification of air where it helps to

remove chemicals and volatile organic compounds through absorption. It is

generally used in association with other types of filter technology, especially

those of the HEPA kind. Other things that this charcoal is used for are in the

treatment of sewerage, as the filter unit in respirators and gas masks, for the

purification of gas and compressed air through filters such as in the life support

in space suits. It is also used for the recovery of gold from cyanide solutions, as

a metal extraction method and for its use in the cleanup of chemical spills.

Another one of the important uses of activated charcoal is in medicine. In the

medical field it is used for reducing the gas that occurs in the intestine, to help

with the treatment of cholestasis where bile flow from the liver is restricted

24

during pregnancy and to help in certain cases with the lowering of cholesterol.

It is also used in medicine to treat acute overdoses and poisonings where it

appears to help prevent the absorption of poisons through the stomach or

intestine. There are many other conditions where activated charcoal is used

and this is especially so where any filtration or purification is needed.

25

CHAPTER 3

METHODOLOGY

3.1 Apparatus

The following equipments were used in carrying out the project work.

Beaker

Weighing Balance

Separating Funnel

Measuring Cylinder

Stirrer

Water Bath

Retort Stand

Stop Watch

Test Tube

Litmus paper

PH Meter

Falling ball Viscometer

Proofing kit

OHAUS Weighing Balance

26

3.2 Reagents

The following materials were used in performing the experiments.

Used Engine oil from petrol and diesel engines.

Charcoal solids

Distilled Water

Concentrated H2SO4

NaOH Pellets

Diesel oil

Ethanol

Universal Indicator

Anti-skinning agent

Wax

27

3.3 Experimental Procedure

Used engine oil with an average SG of 0.925 (about 21.47 °API) at 25°C

obtained from petrol engine of an automobile workshop in Owerri metropolis,

was used to generate the asphaltic sludge as follows.

3.3.1 Production of Asphaltic/Resinous Sludge

150ml of used engine oil was mixed with 30ml of 2.0M H2SO4 in a beaker. The

mixture was placed on a water bath where it was heated and carefully stirred

for about 30mins to a temperature of 50°C.

The beaker was then transferred into cold water bath and was left to cool for

about 48 hours. Two distinct layers were observed- a mobile oil layer, on top of

a dense bottom layer (the asphaltic resin). The oil layer was afterwards

decanted, leaving the sludge. The PH of the layers was then measured.

The procedure was repeated at different acid volume (40 ml, 50ml, 60ml,

70ml, 80ml, 90ml and 100ml) and at different

temperatures(30°C,35°C,40°C,45°C,50°C,55°C, 60°C etc). The weights of sludge

produced in each case were measured and recorded.

3.3.2 Water Washing

The collected sludge was put in a beaker and 100ml of distilled water was

added. The resulting mixture was heated to 100°C and stirred continuously for

about 5 mins to ensure proper mixing.

Then the mixture was allowed to cool, settle and separate into the top dirty

water layer and the bottom layer (the purified sludge). The PH of the sludge

was measured afterwards.

28

3.3.3 Alcohol Washing

The washed sludge was added into a separating funnel where 300g of ethanol

was added and the resulting mixture was stirred vigorously for about 30 mins.

The mixture was separated into two layers. The washing was repeated for the

second time. The bottom dense layer was then collected with a beaker.

3.3.4 Neutralisation of Sludge

This was then followed by neutralisation of the acidic sludge, which was

achieved by adding little quantity of NaOH at a time and testing with the

universal indicator. There was a violent release of fumes and the reacting

solution became hot. This was continued until the solution turned greenish

yellow by 30ml of NaOH, indicating a neutral solution.

3.3.5 Production of Printing Ink

20g of the extracted resinous sludge was added to a beaker containing 20g of

pulverised charcoal. The mixture was stirred with a glass rod and an

appropriate amount of diesel was added into the mixture. This is to help

disperse the black pigment in the mixture.

After the dispersion, additives were introduced in the medium and the

resulting mixture stirred for about 5 mins. This was to improve the physical

properties of the produced ink e.g. viscosity, adherence etc. and to avoid easy

fading.

The above steps were repeated for varying weight of sludge (30g, 40g etc.) to

determine the best formulation.

29

3.3.6 Quality Tests

In order to ensure that the produced ink meets the required quality standard

in the market, the following quality assurance tests were carried out.

Viscosity Test

A sample of the ink was added in to the viscometer cup and channeled under

the viscometer. The viscosity of the ink was measured and recorded.

PH Test

The PH Meter was dipped in to a sample of the produced ink and the PH was

read and recorded.

Tackiness/Printability Test

This was performed using a proofing kit. Sample of the ink was dropped on the

smooth surface of the kit and the proofer was rolled on the drops. It was then

ran over newsprint and observed and the result was noted.

Drying Test

Sample of the ink was taken and printed on the substrate. It was timed from

when the ink was applied on the surface to when it dries using a stop watch.

The drying time was recorded

Adherence Test

A print of the sample of the ink was taken and allowed to dry. The print was

rubbed with hand to see if it will be wiped off.

Gloss Test

The ink was printed on a substrate and allowed to dry. The print was viewed at

a distance from oblique angle of 60°.

30

CHAPTER 4

RESULTS AND DISCUSSION

4.1 RESULTS

The results obtained in the course of the experiments are recorded in the

following tables.

Table 4.1.1 Properties of Produced Sludge and Oil

Property Used Engine

Oil

Produced Sludge Regenerated Oil

PH 2.5 2.0 3.0

Kinematic Viscosity @ 30°C (cSt) 157 198 138

SG @ 30°C 0.925 0.945 0.8707

Flash Point(°C) 158 - 180

Pour Point -5 - -7

31

Table 4.1.2 Quantities of Sludge and Oil Produced at Varying Acid Volume

N/B: Volume of used engine oil is constant at 120ml

Temperature is kept constant at 50°C.

Volume of

Acid(ml)

Weight of

Sludge(g)

Weight of

Regenerated Oil (g)

Acid volume required per g of

Sludge Produced (ml/g)

25.00 52.43 90.58 0.477

30.00 68.12 58.00 0.440

40.00 105.61 80.77 0.379

50.00 139.10 60.80 0.359

60.00 172.38 10.82 0.348

70.00 205.76 5.76 0.340

80.00 243.26 3.12 0.329

90.00 276.64 2.43 0.325

100.00 311.83 1.17 0.321

32

33

Sludge Yield Prediction Models

From the data on the yield of sludge at different acid volume, the following

model was developed to assist in predicting the yield of sludge at higher

volumes of acid.

Two models were tested and the values calculated from these models are

shown below.

Model 1: Yprdt1 = 3.4574X – 34.3504

Model 2: Yprdt2 = 0.0003X2 + 3.418X – 33.3362

Table 4.1.3 Model Calculations and Comparison

X Yprdt1 Yprdt2 Yexp (Yprdt1-Yexp)2 (Yprdt2-Yexp)2

25 52.0846 52.3013 52.43 0.11930116 0.01656369

30 69.3716 69.4738 68.12 1.56650256 1.83277444

40 103.9456 103.8638 105.61 2.77022736 3.04921444

50 138.5196 138.3138 139.10 0.33686416 0.61811044

60 173.0936 172.8238 172.38 0.50922496 0.19695844

70 207.6676 207.3938 205.76 3.63893776 2.66930244

80 242.2416 242.0238 243.26 1.03713856 1.52819044

90 276.8156 276.7138 276.64 0.03083536 0.00544644

100 311.3896 311.4638 311.83 0.19395216 0.13410244

∑ (Yprdt-Yexp) 2

10.20298404 10.0506632

SEEprdt1 = 1.207298285 SEEprdt2 =1.19825249

34

Table 4.1.4 Temperature Effect on Sludge Weight

T(°C) Yexp Yquad Ycubic Y4th (Yqaud model-Yexp)2 (Ycubic model-Y exp)2 (Y4th –Yexp)2

30 55.12 56.4062 54.3066 54.3194 1.65431044 0.66161956 0.64096036

35 58.05 59.4416 59.8638 59.8477 1.93655056 3.28987044 3.23172529

40 63.40 61.7108 63.2541 63.2375 2.85339664 0.02128681 0.02640625

45 65.62 63.2140 64.8277 64.8224 5.78883600 0.62773929 0.63616576

50 66.81 63.9510 64.9349 64.9408 8.17388100 3.51600001 3.49390864

55 62.43 63.9220 63.9257 63.9357 2.22606400 2.23711849 2.26713249.

60 61.08 63.1268 62.1505 62.1549 4.18939024 1.14597025 1.15541001

65 60.12 61.5656 59.9594 59.9510 2.08975936 0.02579236 0.02856100

70 58.20 59.2382 57.7028 57.6815 1.07785924 0.24720784 0.26884225

75 56.14 56.1448 55.7306 55.7082 2.304E-05 0.16760836 0.18645124

80 54.05 52.2852 54.3933 54.3982 3.11451904 0.11785489 0.12124324

N/B Volume of acid is constant at 30ml

Yquad = -0.015322T2 + 1.603T + 22.106

Ycubic = 0.00046695T3 – 0.092368T2 + 5.6328T - 44.1539

Y4th = 3.1702E-07T4 + 0.0003972T3 – 0.086813T2 + 5.4436 - 41.8381

35

Table 4.1.5 Calculated Error Functions

Model SEE R2

Quadratic 3.67828773 0.8429389

Cubic 1.33978537 0.93644576

4th Degree 1.33964517 0.93645197

36

Ink Formulations

Table 4.1.6 Formulation 1 (F1)

Materials Weight (g) Weight %

Charcoal powder 20 26.85

Resinous Sludge 20 26.85

Diesel oil 20 26.85

Easigel 3 4.02

Anti-skinning agent 1 1.34

Wax 0.5 0.67

Black oil 10 13.42

Total 74.5 100

Table 4.6 Formulation 2 (F2)

Materials Weight (g) Weight %

Charcoal powder 20.0 23.67

Resinous Sludge 30.0 35.50

Diesel oil 20.0 23.67

Easigel 3.0 3.55

Anti-skinning agent 1.0 1.18

Wax 0.5 0.59

Black oil 10.0 11.84

Total 84.5 100

37

Table 4.1.7 Formulation 3 (F3)

Table 4.1.8 Quality Test Results

Test F1 F2 F3

Viscosity(cP) 205 215 235

Drying Time(mins) 10 8 5

Gloss Good Very Good Excellent

Adherence Good Good Very Good

Tackiness Good Good Good

PH 7.24 7.35 7.44

Materials Weight (g) Weight %

Charcoal 20.0 21.16

Resinous Sludge 40.0 42.33

Diesel oil 20.0 21.16

Easigel 3.0 3.17

Anti-skinning agent 1.0 1.06

Wax 0.5 0.53

Black oil 10.0 10.58

Total 94.5 100

38

4.2 DISCUSSION

There were three principal studies carried out, they include the effect of acid

volume and temperature on the yield of sludge and the selection of the best

ink formulation. As shown in Table 4.1, the produced sludge has a lower PH

due to the presence of acidic contaminants in the used engine oil. It can be

seen from Table 4.2 and Fig 4.1 that on increasing the acid volume, there was

higher sludge weight. This simply implies that for a larger yield of sludge, more

acid is required. Also it can be inferred that about 0.3-0.5 ml of the acid is

required to produce 1g of sludge. This range arose due to improper mixing,

residence time variation in the batch and systemic errors encountered in the

weighing balance.

From the SEE values calculated for the two models for effect of acid volume on

sludge weight, Model 2 has an SEE of 1.19825249 which is lower than that of

Model 1 (1.207298285). Thus, Model 2 is more accurate and best fit the

experimental data obtained.

The weight of sludge produced with a given volume of acid varies with

temperature as shown in Table 4.4 and Fig 4.3. It was also observed that as the

temperature rose from 30°C to 50°C, the sludge weight increased appreciably

from 55.12g to 66.81g. As the temperature was increased further above 50°C,

the sludge weight began to fall. This drop in the amount of sludge may be due

to the conversion of most of the hydrocarbons by sulphonation reaction of the

acid and the thermal cracking of the sludge formed. Consequently, the

desludging process was carried out at a temperature of 50°C to avoid the

adverse effect of high temperature. Also from the error functions (SEE and R2 )

calculated for the three models, it can be seen that 4th degree model has the

least SEE and R2 values (1.33964517 and 0.93645197 respectively) when

39

compared to the quadratic and cubic model with SEE values of 3.67828773 and

1.33978537 and R2 values of 0.8429389 and 0.93644576 respectively. Thus, the

4th degree model is most accurate and can therefore be selected as the best

model.

As can be seen from the quality test carried out on the three ink formulations

(F1, F2 and F3) and recorded in Table 4.8, F3 has the highest viscosity of 235 cP

and takes the shortest time to dry. It also gave a very good gloss, adherence

and tackiness. The PH test shows that the three formulations are all neutral.

Thus, one can infer that the ink formulation with higher amount of sludge gives

a better result.

40

CHAPTER 5

CONCLUSION AND RECOMMENDATION

5.1 CONCLUSION

Used engine oil is treated to remove most of the oxidation and degradation

products and consequently produce the resinous sludge as a binder for the

black ink. This was achieved with sulphuric acid which proved to be very

efficient because of its poly-functional nature. The amount of sludge produced

is dependent on the volume of the acid. Model 2 is the best for predicting the

effect of acid volume. The desludging process is temperature dependent and

as a result, the yield of sludge was lowered at temperatures above 52°C. The

4th degree model is the best for determining the effect of temperature on

sludge weight. Also, the quality of the produced ink depends solely on the

amount of sludge added. The ink produced using F3 proved to have excellent

and desirable properties and therefore should be considered as the best

formulation for the production of high quality black ink.

4.2 RECOMMENDATION

The oil generated in the desludging process should be further refined using

solvent extraction and clay treatment to obtain base oil for other industrial

purposes. Further studies should be carried out using other acids like acetic

acid in order to know the most efficient acid. Also, efforts should be made in

designing a continuous system for large scale production. Comparative studies

should be carried out on charcoal to further justify its merits over carbon black.

41

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44

APPENDICES

APPENDIX 1

ERROR FUNCTION CALCULATIONS

STANDARD ERROR OF ESTIMATE

For Model 1

10.20298404

N = 9

SEE = [10.20298404/ (9-2)]1/2 = 1.207298285

For Model 2

10.0506632

SEE = [(10.0506632/ (9-2)]1/2 = 1.198252489

For Quadratic Model

= 33.1045896

N = 11

SEE = [33.1045896/ (11-2)]1/2 = 3.67828773

For Cubic Model

= 12.0580683

SEE = [12.0580683/ (11-2)]1/2 = 1.33978537

For 4th Degree Model

= 12.0568065

SEE = [12.0568065/ (11-2)]1/2 = 1.33964517

45

APPENDIX 2

CALCULATION OF THE COEFFICIENT OF DETERMINATION (R2)

R2 =

For Quadratic Model

36.4993924

39.6139114

R2 = 36.4993924/39.6139114 = 0.8429389

For Cubic Model

= 36.5468612

= 36.6647161

R2 = 36.5468612/36.6647161 = 0.93644576

For 4th Degree Model

= 36.4896167

= 36.61086

R2 = 36.4896167/36.61086 = 0.93645197

46

47