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Palm oil Elaeis Guineesis Jacq. production was on rapidly rising path over the past few years in Southeast Asia, where Malaysia and Indonesia was the most spectacular production countries of oil palm. The domination of oil palm plantation in Malaysia agriculture crops has gradually raised and reached a total plantation of over 4 million ha (Zuhri et al., 2009). Today, the dramatically expanding of the palm oil industry in Malaysia yields huge amounts of poorly utilized palm oil wastes. Palm oil wastes such as empty fruit bunch (EFB), mesocarp fiber and kernel shell (Nasri et al., 2012) are the most abundance biomass resources available. In addition, approximately 9.9 million tons of oil palm wastes generated and this amount appraised to increase by 5% annually (Nasri et al., 2012).
After the removal of the oil palm fruit bunches, the residual bunch is known as EFB. It constituents 20% to 22% of the weight of the fresh bunch, and it accounted the largest traces produced from the palm oil mill, reckoning 8.1 million metric tons per year (Dilaeleyana et al., 2012). Only a petty quantity of the EFB is used for power generation in the palm oil mill, but due to its commercial utilization is not widespread, some are used as mulch; meanwhile the rests are dumped into landfills.
It was not economical to handle the EFB since it consumed tremendous energy and cost, as well as the rising of environmental concern. According to Khor (2009), conventional methods such as incineration and compositing of the wastes bring adverse effects to the environment as smoke and solid grains will be released to the air. Currently, to overcome the problems raised, the EFB was further investigated for its potential employment in future. EFB has an enormous potential to be commercially exploited in terms of extreme value supplement products, with considerable quantity is used for mulching under zero burn practice (Basiron et al., 2004). Besides, palm oil industry also cradled extra profits through the exploitation of EFB as they are appropriate for the manufacture of mattress, insulation products, and so on (Dilaeleyana et al., 2012).
New opportunities to convert the palm oil wastes emerged in fuel and chemical field after the application of advanced technologies. Abdullah et al. (2006) reported that the EFB wastes should be upgraded to the renewable chemicals and value supplement products by a potential route known as pyrolysis. Among few thermochemical conversion processes, pyrolysis is recognized as the most promising technique to convert the EFB to solid char, bio-oil, and lastly gases rich in hydrogen, depending on the pyrolysis conditions (Ertas et al., 2010). Pyrolysis is a highly complex process where the thermal degradation process occurs at intermediate temperatures, heated in the absence of oxygen, yields high quantity of condensable liquids with minimum of charcoal products and gases if the process is well controlled. Nevertheless, pyrolysis process is not only influenced by the properties of the EBF itself, but also by the operating conditions (Yang et al., 2006).
The condensable liquid or commonly known as bio-oil is a mixture of homogenous hydrophilic (oleo- phobic) and can be separated into two layers, consisting of light bio-oil (upper layer) and heavy bio-oil (bottom layer) with respective characteristics. Bio-oil is a polar and highly valuable bio- fuel which can be easily transported and stored, and can be used for the production of specialty chemicals (e.g. flavorings) although it is high density (about 1 200 kg/ m3) and highly oxygenated fuel, thermally unstable, viscous and chemically quite complex. A component characterization such as Fourier Transform Infrared (FTIR) is vital in determining the functional groups of the bio- oil as well as the thermal behaviour of the bio-oil (Nasri et al., 2012). On the other hand, Gas Chromatography- Mass Spectrometry (GCMS) was used to study the chemical characterization of the bio-oil, as well as the nature and class of organic compounds present in the bio-oil. Then, Thermogravimetric analysis (TGA) and Differential Scanning Calometry (DCS) are important in assessing the volatile and non-volatile fractions (thermal behavior) of the heavy bio-oil. Through elemental analysis, the derived components of the bio-oil can be determined. Water soluble fractions (hydrophilic) and water insoluble fractions (hydrophobic) of the bio-oil were being investigated in this research.
The sustainable EFB wastes generated from the palm oil biomass are numerous. Thus, new chemicals are created from the wastes after undergoing a series of chemical processes to be used in daily life nowadays. The bio-oil derived from the EFB is separated into light and heavy bio-oil and the hydrophilic heavy bio-oil is converted to hydrophobic property. According to Oliveira et al. (2001), the hydrophobic solvent is a kind of liquid material that is able to make the base material hydrophobic when painted. The recognized effect of hydrophobic effect on the solid surface influences the adhesion of bacteria and microorganisms. Less pathogen are attached on the surface due to this reason. On the other hand, it is obvious that the hydrophobic effect increase the corrosion resistance of a surface (Zhu and Jin., 2007) by reducing the oxidation on the metal parts.
Indoor Air Quality (IAQ) and health problems created by contaminated air significantly influenced community health nowadays. Hazards associated with poor outdoor air quality have been heard and most people merely concerned about the outdoor air they breathe in. Conversely, in fact, the indoor air was two to five times or 100 times more polluted than the outdoor air. The moist surface of the structures inside a building exposed to the atmosphere provided the coziness environment for the growth of bacteria, fungal, mold and viruses. These microorganisms will colonize and eventually form a bio- film, or commonly known as jelly or slime. Unfavorable health effects such as respiratory ailments, lung infections, fatigue, asthma, allergies, and an extreme decline in concentration and work productivity arisen due to the aggravation of the indoor air quality. Nevertheless one of the contributors to this problem was building maintenance system, basically to operate mainly as thermal comfort, has brought countless health problems, lowered machine efficiency and down time for cleaning. At present, designers and manufacturers respond to the ever evolving market demands for comfort, simple and safe usage of products that can overcome wide range of cleaning problems. Yet, there are still alkali-based and acid-based cleaning agents that polluted the indoor environment after cleaning. Problems such as corrosion, fouling, brittleness, reduction of air flow through the heat exchange of the Heating, Ventilation and Air Conditioning (HVAC) system and downtime for system cleaning are still existing.
The extraction of hydrophobic property of the heavy bio-oil is a new research where it functions to replace the existing alkali-based and acid-based cleaning agents which will cause fouling and corrosion to metal surfaces. Due to its sustainable properties and as low cost wastes, further research can be conducted to reduce the environmental issues resulted from the disposable of EFB. By conducting this research, there are escalating hope to overcome these circumstances, where building maintenance system can be cleaned whilst not contaminating the indoor air quality and by the same time, increasing the lifespan of the building maintenance system.
Objectives of Study
The objectives of the study are:
1.3.1 To investigate the effectiveness of 1-octacosanol and hexamethylenetetramine on hydrophilic-hydrophobic of bio-oil conversion.
1.3.2 To measure the degree of hydrophobic property of heavy bio-oil before and after adding of 1-octacosanol and hexamethylenetetramine.
1.3.3 To investigate the performance of hydrophobic heavy bio-oil on surface by using dust deposition test.
Scope of Study
The scope of this research generally included the followings:
Empty fruit bunch (EFB) extracted from the oil palm biomass undergo pyrolysis process to derive the raw bio-oil. The raw bio-oil is separated into light and heavy bio-oil. The heavy bio-oil is synthesized from hydrophilic to hydrophobic property. 1-octacosanol is added to the heavy bio-oil in several quantity ratios. The hexamethylenetetramine is then added to enhance the hydrophobic properties of the heavy bio-oil.
Physical properties of the heavy bio-oil which is the contact angle will be investigated. Furthermore, in determining the functional group of the heavy bio-oil, Fourier Transform Infrared (FTIR) was used, while in determining the chemical compounds in the heavy bio-oil, Gas Chromatography- Mass Selectivity (GCMS) was utilized.
A layer of upgraded heavy bio-oil is applied on a surface and kernel dusts are sprinkled on the surface so as to determine the amount of dust deposition. At last, the upgraded heavy bio-oil undergoes the biodegradability test.
The raw heavy bio-oil which is hydrophobic in nature is converted to hydrophobic by the addition of 1-octacosanol and hexamethylenetetramine.
2.1 Necessity of Hydrophobic Property
Hydrophobic comes from the Greek root 'hydros' meaning water and 'phobos' meaning fear. Thus, literally, hydrophobic means fearing or hating water, but in chemistry it is the tendency of a material or surface to repel water. In other words, the hydrophobic surface is water repellent, in contrast with a hydrophilic surface which is easily wetted. According to Amin et al. (2007), hydrophobicity of any material is its resistance of the water to flow on its surface. A surface is considered to be highly hydrophobic if it resists the flowing of water dropped on it and is hydrophilic (least hydrophobic) if the dropped water flows in form of tracks on its surface. For this reason, a drop of water located on a hydrophobic surface will ball up instead of spreading out (Torigoe, 2006).
Hydrophobicity of a material or substance can be designated using the contact angle on the material surface (Î¸) that the liquid droplet makes when it comes into contact with a solid surface, and this angle is a measure of surface wettability. The surface which can be wetted easily allowed water to touch a large surface area and thus, creates a contact angle of less than 90â°, whereas hydrophobic surface gives lesser water surface contact and hence the contact angle is greater than 90â° (Feng et al., 2002). Figure 2.1 illustrated the contact angle (Î¸) measurement of a liquid droplet with a solid surface.
Figure 2.1 Contact angle measurements.
Highly water-repellent surfaces (super-hydrophobic or ultra-hydrophobic) are biologically inspired with the lotus leaf being the classic example. Doshi et al. (2005) recalled that the water droplets on the Lotus plants roll rather than flow on the surface of the leaves, these rolling droplets entrain contaminants and parasites, thereby cleaning them from the Lotus leaf surface. It is currently recognized that the captivating fluid behaviours like the rolling and bouncing of the liquid droplets and also the self-cleaning of the contaminants on the Lotus leaf surface, arise from a combination of the low interfacial energy and the rough surface topography of waxy deposits covering their leaves, or in other terms, the hydrophobic surfaces. Recent discoveries have linked the mechanism for the self-cleaning of a lotus plant to a microscopic morphology leading to ultra-hydrophobic surfaces (i.e. surface contact angle with water is greater than 150â°). This finding has sparked the development of surfaces that producing the same effect (Barkhudaov et al., 2008).
There has been growing interest in bacterial cell-surface hydrophobicity and its relation to bacterial adhesion since last decade (Wibawan et al., 1992). Recent research into the features of extreme water-repellent surfaces has leads to evolve of the super-hydrophobic surfaces. Certain super-hydrophobic surfaces can cause water and even oils to roll off leaving little or no residue on the surface, at the same time carry away any resting surface contaminations (Roach et al., 2007). Such behaviour of liquid drops on a surface is important in a wide range of applications. In some situations, the water repelling surfaces advocated huge opportunities in coating applications and also as the chemical and biological agents in preventing anti-fouling for marine vehicles and Heating, Ventilation and Air- Conditioning (HVAC).
2.2 Introduction of Biomass
2.2.1 Biomass as a Source of Renewable Energy
Biomass as a renewable resource can be derived from any essentially organic material includes firewood plantation, forestry residues, wood, agriculture crops, animal manures, municipal solid wastes; waste from food processing etc, that can be utilized as an energy source, where the source of entire energy in biomass is from sun. In other context, biomass is unceasingly undergoing a complicated series of physical and chemical transformations and being regenerated while giving off heat (a form of energy) to the atmosphere. Biomass can be considered as a renewable energy source since its supplies are unlimited. In modern era, biomass is considered as a clean, sustainable and potentially renewable energy source that dedicates to the world energy demands and can replace fossil fuels (Zhang et al., 2010). The expanding interest for biomass in substituting fossil fuels is due to the upcoming depletion of petroleum coupled with the raising of awareness on the passive impacts of fossil fuels towards environment, accordingly to Murtala et al. (2012). Thus, as stated by Pedro et al. (2008), the study on satisfaction of the economic and environmental concerns of biomass is of extremely importance related to fossil fuels.
2.2.2 Potential of Biomass Energy Resources
Due to the increase in crude oil prices and environmental concerns, a search for sustainable and cheap fuel has attracted significant attention. Nowadays, the utilization and amendment of biomass renewable energy resources is drawing more attention and playing an paramount important role in the world's technologically and economically perspective. This is due to the involvement of a series of important maneuvers that involve energetic and industrial activities which greatly influenced human daily activities, as they contibuted to the energy needs of contemporary society both the developed and developing economics worldwide. The use of biomass offers a variety of advantages, and their applications are found in energy sector, fertilizer, fiber, textile, paints and coating, food industries, pharmaceutical, etc. Biomass provides the only source of renewable liquid, gaseous and solid fuels, attributed by Bridgwater et al. (2004). As such, they became a promising option as valued alternatives for fossil- based raw materials (Nasri et al., 2012). In other words, they can be converted to oils and are a logical choice to substitute fossil fuels. By deriving more energy from renewable biomass feedstocks, the reliance on petroleum (fossil fuels) might decrease significantly. For this reason, several efforts for converting renewable biomass to beneficial energy have been developed and new conversion processes have been issued out (Mohan et al., 2005). The introduction of new and advanced technologies in chemical processing such as gasification furnish new opportunities for the conversion of these tremendous natural renewable resources (biomass). Pyrolysis is considered as one of the most frequent employed technologies in converting the biomass into stable end products, yielding bio- oil, tar, char and volatiles (gases) depending on the pyrolysis conditions (i.e. sample size, temperature and reaction time) (Murtala et al., 2012).
2.2.3 Biomass and Its Environmental Impacts
Currently, the rapid utilization of fossil fuels for energy production has become a growing concern, both with regarding the harmful environmental effects from burning fossil fuels and in a long term perspective since the resources is diminishing (Chueluecha et al., 2012, Ahmad et al., 2010). In the present circumstances, oil prices are volatile while the supplies are finite (Amin et al., 2012). Also, the alarming increasing trend of carbon dioxide will significantly leads to the change in global climate and it is best portrayed via today's catastrophic greenhouse effects (Ahmad et al., 2010). Therefore, renewable biomass energy is vital contributor to the energy portfolio as it contributes to world energy supply and economic security (Sukiran et al., 2009); reduced the dependency of fossil fuels, provide opportunities in reduction of greenhouse gas concentrations in the atmosphere (Nasri et al., 2012), and lastly renovate the energy sources structure (Ahmad et al., 2010). In essence, land degradation and soil erosion can be greatly reduced as well as safeguard of watersheds (Ahmed et al. (2012). In response to environmental crisis, use of biomass minimizes air pollution as its utilization contributes no net carbon dioxide to the atmosphere (Murtala et al., 2012). Innovation designs and processes (Murtala et al., 2012) to convert biomass such as empty fruit bunch (EFB) into petroleum like liquids such as bio-oil (Amin et al., 2012) would be the most promising ways for tentative in decreasing the carbon dioxide concentration.
2.2.4 Overview of Palm Oil Industry in Malaysia
Malaysia is one of the countries in Asia that practiced agriculture sector as one of its major industries at the economic aspects (Kabbashi et al., 2007). According to Khoo and Chandramohan (2002), Malaysia is the world's largest producer and exporter of palm oil with a 50% and 61% share of palm oil production and exports respectively. This is due to the fact that the palm oil industries in Malaysia are at the forefront of technology and production in both the plantation (upstream) and oleo-chemical (downstream) products for the global markets. Other than that, Malaysia also accounted for the highest percentage of global vegetable oils and fats trade in the year 2008 as reported by Lim (2010). Undoubtedly, the growing of palm oil industries has transformed Malaysia into a commercial powerhouse in tropical agribusiness.
Besides producing oils and fats, there are also charming interests concerning oil palm wastes as renewable energy sources. The wastes generated are palm kernel shell, mesocarp fibers and empty fruit bunches (EFB). Lim (2010) observes that the palm oil wastes such as the EFB can be a potential renewable energy generator. EFB can go through a series of conversion and the resulted oil can be used as the bio- fuels to replace fossil fuels. Table 2.1 below indicated the palm biomass wastes generated in Malaysia and its main uses in the year 2005.
Table 2.1 Palm biomass wastes generated in year 2005 (Nasrin et al., 2008)
Quantity, million tonnes
Moisture content, %
Calorific Value, kJ/ kg
Palm kernel expeller
2.3 Characteristics of Empty Fruit Bunch (EFB)
Generally, knowledge of the physical and chemical characteristics of the EFB is essential for optimizing the efficiency of any thermochemical conversion process.
2.3.1 Empty Fruit Bunch (EFB)
Empty fruit bunch (Figure 2.2) has a celebrated relevance to Malaysia as a huge quantity of oil palm wastes is generated. EFB is another valuable source of biomass that can be converted to useful energy. The oil and cellulose within the EFB can be extracted by specific physical and chemical processes. The extracted oil is known as bio- oil. Fresh EFB returns mineral nutrients and organic matter to the land and helps to maintain soil fertility, thus, it is widely used as a mineral fertilizer either by direct application or, in certain circumstances, after incineration and composting. However, due to the pollution problems caused by the incineration of EFB, this method has been prohibited by the government.
Figure 2.2 Empty fruit bunch (EFB) (http://www.etawau.com)
2.3.2 Physical Characteristics of EFB
EFB is characterized by high moisture and volatile content, low specific energy and has low ash content. Table 2.2 and Table 2.3 below indicated the ultimate (elemental) analysis and proximate analysis of the raw EFB respectively.
Table 2.2 Ultimate (elemental) analysis of EFB (Abdullah and Gerhauser, 2008)
Measured Ultimate Analysis (wt %)
Table 2.3 Proximate analysis of EFB (Abdullah and Gerhauser, 2008)
Measured Proximate Analysis (wt %)
High Heating Value (MJ/ kg)
2.3.3 Chemical Characteristics of EFB
EFB contains a high content of lignocellulosic materials, which contains about 30% of solid, 65.5% of holocellulose (consisted of Î±-cellulose and hemicelluloses), 21.2% lignin, 5.6% hot water soluble components, 4.1% alcohol- benzene soluble fractions, and 3.5% of ash (Shahriarinour et. al., 2011).
2.4 Current Technologies and Conversion Routes of Bio-oil
Previously, EFB had little commercial value and its disposal problem arose due to its bulk density. Thus, many oil palm industries chose to burn the wastes and consequently, caused air pollution. The passive impacts of EFB wastes towards environment can be minimized while maximized the value of the EFB simultaneously by converting the huge EFB wastes into energy, rewarding the base for the production of a wide range of chemicals, biomaterials and fuels for power and heat generation. Since the conversions of EFB offered numerous benefits, they accommodated increasing interest for the production of bio-oil. The basic conversion routes or pathways of EFB wastes into its corresponding applications are demonstrated in Figure 2.3 below.
Figure 2.3 Summary of EFB wastes conversion routes and its subsequent applications.
With modifications, bio-oil can be used to substitute for fossil fuels in green power and heat generation including diesel engines, gas turbines, boilers and furnace. Powerful market for the bio-oil elevated due to the acceleration of global demand towards the production of clean energy and improvement of air quality. As a green and sustainable fuel, bio-oil emitted no SOx compounds to the atmosphere and little amount of NOx and neutral CO2. Bio-oil can be easily stored, pumped and transported in a manner similar to petroleum based products to equalized energy demand and distribution. In fact, it is economical to transport and store the bio-oil as they are cheaper.
A wide range of chemicals can be extracted or derived from the bio-oil, and are an adorable possibility for producers' of bio-oil as it generally offer much higher value added compared to fossil fuels based products. It has the potential to serve as the basis for a wide spectrum of chemical products. Bio-oil can be further converted to a wide variety of value added derivatives such as flavourings, resins, fertilizers, solvents, antifreeze and pharmaceutical through oxidation, reduction, dehydration, hydrogenolysis and direct polymerization (Murtala et al., 2012) to meet customers' specifications.
The first is the liquefied of EFB directly by high temperature pyrolysis. The second approach is the gasification of EFB and its conversion to hydrocarbons. Thirdly is the conversion of EFB to ethanol through fermentation process.
The pyrolysis process is relatively complex which involved the thermal decomposition of the bio- oil into liquids, gases and solid residue (char) in the absence of air, generally used to be anhydrous. The properties of the products resulted from pyrolysis are hard to presage as they are greatly dependent on the pyrolysis conditions such as the temperature of the process, the heating rate, the presence of water or oxygen and the nature of the feedstock (Azizan et al., 2006). Pyrolytic products can be utilized as fuels or as solvents in industries and households with prior upgrading. In fact, products obtained from pyrolysis process are much more refined to produce high quality fuels with higher efficiency. Primarily, there are two types of pyrolysis processes carried out on the EFB, which are distinguished by temperature and the residence time of the reaction; those are slow pyrolysis and fast pyrolysis.
Slow pyrolysis or conventional pyrolysis is characterized by slower heating rates, lower temperatures and longer retention times. The slow pyrolysis of EFB was carried out by using a pilot kiln. According to Khor et al. (2009), initially, the EFB is heated internally with partial burning which was ignited using the liquefied petroleum gas (LPG) fire. The heating rates are about 0.1 to 0.2Â°C per second and the prevailing temperatures are about 600Â°C, where the temperatures are measured using thermocouples equipped on the kiln. During slow pyrolysis, the moisture of the fresh fruit bunch is removed at a temperature not exceeded 110Â°C. Then, the EFB is slowly devolatilized from 240Â°C to 600Â°C, yielded tar and char as the main products.
To minimize the production of char and maximize the production of liquefied bio-oil, fast pyrolysis is favored at higher heating rates and shorter residence times, usually with temperature of higher than 550Â°C. Due to shorter reaction time, fast pyrolysis yields high amount of liquid, which is up to 80 wt% (Khor et al., 2009). Notably, tar and char produced by this process is considerably reduced. For this reason, this process is more sustainable and suitable to be used in deriving bio-oil from EFB. Figure 2.4 below indicated the schematic diagram of the pyrolysis of EFB in a batch reactor.
Figure 2.4 Schematic diagram of EFB pyrolysis process in a batch reactor. (Nasri et al., 2012)
Gasification or sometimes referred to as thermo- chemical process, partially oxidizes EFB into a small molecules of fuel gas mixture (syngas) under severe conditions in very short reaction time, composed of hydrogen, carbon dioxide, nitrogen, carbon monoxide, methane and other compounds. The gasification reaction is often cited as complicated and complex as it involves multiple reactions that occurred simultaneously to produce the gaseous and liquid mixture. Frequently, inorganic catalysts are required to ameliorate the product quality. Syngas can be converted to methanol, ammonia and oxy-alcohols which are the essential chemical intermediates used in industries as explained by Murtala et al. (2012).
Fermentation is a traditional method which utilized the biological enzymes, living organisms or acids as the catalysts in the conversion of EFB into specialty and commodity chemicals (Murtala et al., 2012). On the other hand, fermentation is a bio- catalyzed reaction that converts carbohydrates or simple sugars contained in the EFB to ethanol by the aided of yeast as presented by Cheng et al. (2007), with the carbon dioxide as the side product. Besides, lactic acid, citric acid and acetone- butanol have been manufactured through yeast and bacterial fermentation processes. Overall, fermentation offered ordinary yet effective and flexible treatment of EFB wastes from the oil palm industry.
The bio-oil conversion methods from EFB have been expressed in detail in Section 2.3. Each of this method has its own advantages and benefits. But, pyrolysis process is the most widely used alternative in converting the EFB to bio-oil.
Characteristics of Bio-Oil
Bio-oil is a dark brown mobile organic liquid, which comprised of highly density oxygenated compounds. It is viscous and non- homogenous, with an acrid and smoky smell. Its colors range from dark green to dark brown depending on the feedstock and the manufacture process of the oil. Bio-oil composed of hundreds of different organic compounds, ranging from volatile compounds such as acetic acid to more stable phenols. The main components of the bio-oil include phenols, acids, ketones, low molecular weight alkenes and aromatic species as being investigated by Khor et al., 2009 previously. According to Perez et al. (2007), the grouping of bio-oil into chemical families is necessary because these compounds can be treated as groups instead of hundreds of compounds.
Due to the presence of 15 to 35wt% of water, the bio-oil is hydrophilic. Generally, bio-oil is made up of two phases, the upper phases is the light emulsion containing water soluble compounds and lightly oil components, whereas the bottom phase is a water insoluble, large molecule oily mixture and large molecular weight phenols (methoxy and ethoxy groups) with high viscosity, namely heavy oil (Yang et al., 2010). The oil is chemically unstable, which decomposed over time or when exposed to high temperature. However, the instability does not hinder bio-oil from being used in commercial applications due to the previous study which has found that the samples of bio-oil remained stable even though they have been stored for a year (Easterly et al., 2002). Thus, bio-oil can replace fossil fuels in some applications, for instance it can be burned in diesel engines or boilers as reported by Abdullah and Gerhauser (2008).
Bio-oil is moderately acidic, having a low pH range of 2.5 to 3.0 (similar to that of the acidity of vinegar), as bio-oil comprised of substantial amount of organic acids, mostly acetic acids and formic acids as stated in the finding of Sukiran et al. (2009). Acidity of the bio-oil resulted in highly corrosive property and intensively violent at elevated temperature (Khor et al., 2009), thus the construction materials for the bio-oil storage tank or vessels need to be made of anti-corrosion material, such as stainless steel, plastic and fiberglass. In addition, the bio-oil needs to be upgraded so as to minimize its corrosion characteristic. The physicochemical properties of the bio-oil at are presented in the Table 2.4.
Table 2.4 Characteristic of bio-oil (Khor et al., 2009)
Calorific Value (MJ/ kg)
ASTM D- 5865
Total Ash (%)
ASTM D- 482
ASTM D- 4928
Acidity (mg KOH g-1)
ASTM D- 664
Density (g/ cm3)
ASTM D- 4052
Ultimate analysis (wt/wt %)
ASTM D- 5373
ASTM D- 5373
ASTM D- 5373
ASTM D- 4294
Composition of Bio-Oil
Gas Chromatography-Mass Spectrometry (GC-MS) is fundamental in determining the chemical functional groups of bio-oil. Previous researchers have shown that there are hundreds of compounds identified in the bio-oil. Here, only a small number of compounds from the findings of several researchers will be listed out. The information in Table 2.5 indicates that the EFB bio-oil is a complicated organic compound that mainly consists of acids and heterocyclic substances.
Table 2.5 Chemical compounds of bio-oil according to the GCMS (Sukiran et al., 2009, Dilaeleyana et al., 2012, and Khor et al., 2009).
Alpha- d- Ribopyranoside, phenyl
Phenol, 2- methyl
Beta- d- Lyxofuranoside, phenyl
Phenol, 3- methyl
Butanoic acid, 4- phenoxy
Furan, 2,5- dimethyl
2H- Pyran, 3,4- dihydro
Phenol, 2, 6- dimethoxy
Cyclopentanone, 2- methyl
2- Pentyn- 1- ol
Hexadecanoic acid, methyl ester
2- Cyclopentane- 1- one, 2- methyl
14- Pentadecenoic acid
Cyclopropaneoctanoic acid, 2- hexyl-, methyl ester
Bio-oil can be separated into highly polar water soluble components and low polar water insoluble components. The water insoluble material consisted of lignin-derivative compounds or pyrolytic compound. Effective separation method must be employed to separate the light and heavy fractions of the bio-oil. Phase separations may merely occur above certain water contents, which is above 30 to 45% of the moisture content. Generally, there were three basic phase separations of the bio-oil, known as liquid- liquid extraction, addition of inorganic salts or solution of inorganic salts to the bio-oil and lastly the adding of hydrophobic polar solvent and aqueous NaHSO3 or aqueous alkali.
Liquid- liquid Extraction
The fractionation of the raw bio-oil was by liquid-liquid extraction following the separation sequence presented in Figure 2.2. Extraction was carried out based on the difference in solubility of the components of bio-oil which leads to a separation of the components according to physical and chemical properties. Same separation approach has been used in other oils as reported by Perez et al. (2007).
In the initial stage of the separation process, 250mL of distilled water is added simultaneously to the 500mL of bio-oil (ratio of 1:2). The mixture is then stirred and maintained for two hours using magnetic stirrer at 20Â°C and 8rpm and left for 24 hour until two clear layers (heterogeneous) were seen. After that, the bio-oil was separated by gravitational forces which were also known as centrifugal settling using centrifuge separator. The heavy bio-oil (bottom layer) is separated out from the lighter layer (light bio-oil) and then collected in a beaker. This operation was performed so as to separate the top emulsion phase and the heavy oil at the bottom layer.
However, the addition of water would result in difficultly of separation, and thus yielded only a small percentage of the heavy bio- oil and with no clear separation.
Phase Separation by Adding Aqueous Inorganic Salt Solution
Song et al. (2009) reported that the bio-oil can be separated through the addition of various inorganic salts. The phase separation can be performed by adding a small amount of inorganic salts such as LiCl, CaCl2, FeCl3, (NH4)SO4, K2CO3, or Fe(NO3)3 into the bio oil under cooled water bath condition (temperature lower than 15Â°C). The mixture is the sent to the sonicator and the sonication process (sound vibration) will cause the mixture separate into two phases (upper and bottom phase) quickly. The addition of LiCl solution into the bio-oil will generate higher yield of the heavy bio-oil compared to the other salt solutions and the liquid-liquid extraction of the bio-oil mentioned in Section 2.6.1. This kind of method will give a clearer separation of the light and heavy bio-oil.
Separation with the Simultaneous Addition of Hydrophobic Polar Solvent and Aqueous NaHSO3 or Alkali Solution
The simultaneous utilized of a hydrophobic polar solvent and anti- solvent (aqueous NaHSO3 or alkali solution) or water in the extraction of bio-oil, attributed by Zilnik and Jazbinsek (2012). Methyl isobutyl ketone (MIBK) was selected among other hydrophobic polar solvents as it was the most efficient solvent for extraction of the bio-oil. However, the addition of the MIBK to the bio-oil normally does not result in a splitting of phase; therefore an anti-solvent like water, aqueous NaHSO3 or aqueous NaOH is added to induce the phase separation at ambient condition. The mixture is then stirred using electronic stirrer at 5Â°C and 8rpm for about two hour and left until two clear layers were seen. The light bio-oil is extracted and the remaining heavy bio-oil is evaporated using vacuum evaporation system. The MIBK solvent is evaporated from the heavy bio-oil. The separation of the bio-oil using this method gives the most yield of heavy bio-oil.
2.7 Comparative study in bio-cleaning
The indoor environment cleaning purposes are to keep a tolerable level of perceived cleanliness, to control potential risks of infection from microorganisms, to shun surface degradation, and to control dust exposure in general, as stated by Wolkoff et al. (1998). In today's diverse market, cleaning product manufacturers faced with the challenge of balancing two significant goals, those are creating effective cleaning agents for removing indoor pollutants such as dust, particulates, bacteria, mold, microorganisms, while not adding additional volatile organic compounds (VOCs) contaminants back into the indoor air. Besides, the cleaning products should be designed to reduce the emission of Ozone Depleting Substances (ODS) and Hazardous Air Pollutants (HAPs).
Using the conventional cleaning products of acid or alkali- based, they merely remove the microorganisms and dust superficially and temporarily, while compacting the contaminants deeper into the narrow area of the enclosed surface which will cause even more blocking. Moreover, the acid or alkali-based cleaning products devastated and coarsen the top coat paint of the surface, creating a more comfortable environment for the growth of microorganisms that eventually become a bio- film. Generally, bio-films will form after four days in humid conditions after cleaning. Airborne contaminants originated from the bio-film causing both the occupants and cleaners of affected building sick, triggering health effects such as asthma, fatigue and suppression of the immune system. Legionnaires Disease is just one deadly example.
Awareness arose corresponding to the attachment of dust and microorganisms on the surface which leads to building related illness; contributed to a study on cleaning of the HVAC. Research regarding the invention of green cleaning products that meet today's market demands for effective, yet safe preservation of indoor environments have been conducted to gaze for the ecological friendly cleaning agents. The green cleaning products meet the necessities of protecting the surrounding environments as being biodegradable and discharge no or minimum amount of toxicity to the aquatic organisms when disposed to the water streams.
Few years back, the biotechnology sector provided a broad perspective of cleaning the cultural heritage surfaces. However, the removal process of bio-film involved in situ production of hydrogen peroxide (H2O2) using glucose oxidase as a model enzyme system. The H2O2 produced will oxidized the cleaned surface and lead to corrosion (Valentini et al., 2010). Thus, this method was not effective in cleaning the surface. Other than that, soy solvents or commonly known as methyl soyate were also involved in certain cleaning applications, such as parts cleaning, removal and dissolving of paints, coatings, inks and adhesives. The methyl soyate was a viable commercial green solvent alternative, and has been implicated in the continuing replacement of hydrocarbon and chlorinated solvents. In other words, the methyl soyate offered yet better green solvent replacement choices to the industrial petrochemical- based solvents market. Unfortunately, the performance properties of the methyl soyate have been perceived to have slow evaporation rate and leaving film residue after being applied on the surface. Furthermore, the utilization of such solvents is not effective in cleaning and removing the bio- film formed on the surface.
2.8 Upgrading of Bio-oil Hydrophobic Properties
According to Zhang et al. (2011), the raw bio-oil derived from pine chips can be catalytic upgraded using neat model olefin and a mixture of 1-octene and 1-butanol over sulfonic acid resin catalysts at temperature ranging from 80 to 150â°C. By this way, the water content and acidity of the bio-oil were reduced and simultaneously increased the hydrophobic and heating value of the bio-oil. As explained further by Zhang et al. (2011), most of the organic acids such as formic acid, acetic acid, propanoic acid, butanoic acid, butanedioic acid etc. were converted into butyl or octyl esters via esterification after upgrading. The furan and phenol derivatives also diminished in amounts and this will contributed to more stable bio-oil. Furthermore, some ketones totally disappeared and the reducing of such compounds (furan, phenols and ketones) in the bio-oil will increase the hydrophobic property of the product. In addition, the water content of the bio-oil upgraded with 1-octene and 1-butanol was greatly reduced. Undoubtedly, the upgraded bio-oil has become more hydrophobic, and thus, this implied that the combined upgrading of the bio-oil with 1-octene and 1-butanol and also olefin was particularly promising in increasing the hydrophobic properties of the oil.
Hydrophobic Surface Created by Hydrophobic Heavy Bio-Oil
Hydrophobic and hydrophilic are frequently used as the descriptors of surfaces. A surface is hydrophobic if it tends not to adsorb water or be wetted by water. A hydrophobic surface is one in which the contact angle of water on the surface is from 90â° to 180â°, as attributed by Zhang (2012). When the upgraded hydrophobic heavy bio- oil was applied, wiped or sprayed on a surface, it will create an immediate hydrophobic surface.
The hydrophobic surfaces created by upgraded heavy bio-oil contributed numerous valuable properties, including the ability to be self-cleaning, anti-bacteria, anti-reflecting, and anti-fogging, as well as protecting metallic surfaces from corrosion. The self-cleaning characteristic makes it suitable for rendering a surface anti-microbial and therefore avoids bio-fouling. In other words, it presents a viable solution for the prevention of growth of microorganisms on the moist surface. For this reason, the upgraded hydrophobic heavy bio-oil derived from palm oil biomass can be used as a cleaning agent in removing the dust and microorganisms attached on the surfaces.
3.1 Flowchart of the Research
Figure 3.1 clarified the entire content of the research. It was meant to make a clearer picture of the research methodology.
Upgrading of HBO by addition of 1-Octacosanol
Fractionation of raw Bio-oil to produce Heavy Bio-oil (HBO)
FTIR, GCMS, Contact Angle
Addition of chemical binder: Hexamethylenetetramine
Dust Deposition Test and Biodegradability test
Figure 3.1 Flowchart of research.
Figure 3.2 Raw Bio-oil
The raw bio-oil used in this experiment is pyrolyzed from the empty fruit bunch (EFB) supplied by oil palm plantation of Koperasi Kampung Jawi Johor Bharu Berhad (Provincence of Johor State). The raw EFB feedstock was cleaned and dehydrated at 100Â°C for a day for pyrolysis process. Figure 3.2 above showed the raw bio-oil used in this study.
3.2 Fractionation of Raw Bio- Oil and Production of Heavy Bio-oil
The fractionation of the raw bio-oil was by liquid-liquid extraction following the separation sequence presented in Figure 3.3. Extraction was carried out based on the difference in solubility of the components of bio-oil which leads to a separation of the components according to physical and chemical properties. Same separation approach has been used in other oils as reported by Perez et al. (2007).
In the initial stage of the separation process, 250mL of distilled water is added simultaneously to the 500mL of bio-oil (ratio of 1:2). The mixture is then stirred and maintained for two hours using magnetic stirrer at 20Â°C and 8rpm and left for 24 hour until two clear layers (heterogeneous) were seen. After that, the bio-oil was separated by gravitational forces which were also known as centrifugal settling using centrifuge separator. The heavy bio-oil (bottom layer) is separated out from the lighter layer (light bio-oil) and then collected in a beaker. This operation was performed so as to separate the top emulsion phase and the heavy oil at the bottom layer. Figure 3.4 below showed the stirring process of the bio-oil on the magnetic stirrer.
Liquid- liquid Extraction:
250mL of water
500mL of raw bio-oil
Stirring (2 hour) - left for 24 hour
Light Bio-oil (alkenes and low molecular weight lignins)
Heavy Bio-oil (HBO)
Figure 3.3 Fractionation schemes of raw bio-oil with water to upper and bottom layers
Figure 3.4 Stirring process of the bio-oil on the magnetic stirrer at temperature of 20â°C and 8rpm.
In this experiment, only heavy bio-oil (HBO) will undergo physical and chemical characterization and further treatment in order to assess the feasibility on conversion of HBO hydrophilic properties to hydrophobic properties.
3.3 Characterization and Performance Testing of Raw Heavy Bio-oil
First of all, the raw heavy bio-oil will undergo a series of performance testing in order to determine the physical and chemical composition of the heavy bio-oil and hydrophobic properties of heavy bio-oil components.
3.3.1 Fourier Transform Infra-red (FTIR) Spectrometer
Functional groups of the raw heavy bio-oil were analyzed using FTIR spectrophotometer. In this research, Potassium Bromide (KBr) pellet technique is employed. Mixture of the samples (Table 3.1) and KBr with ratio of 1:100 was hydraulic pressed and prepared for an analysis using Fourier Infra-red Spectrometer Spectrum 2000 Explorer Perkin Elmer Limited. The spectra data was used to identify the existing organic compounds by matching the fingerprint of the sample with the standard IR- spectra of hydrocarbons.
3.3.2 Gas Chromatography-Mass Spectrometry (GC-MS)
Gas chromatography (GC) is used to separate various organic compounds found in the raw bio-oil and upgraded bio-oils (Table 3.1), whereas the mass spectrometry (MS) determines the molecular formula of the organic compounds that were separated from the GC. In this research, the composition of the raw heavy bio-oil was analyzed using Agilent J & W Inc., with the separation process performed by HP- 5 MS nominal coalumn with thickness of 0.25 Âµm (30mm x 250Âµm) and mass selectivity (MS) detector. The oven was operated at 50Â°C for 30 second and then ramped at 10Â°C min-1 up to 250Â°C, using helium (purity of 99.99%) as carrier gas at a constant flow of 1 ml min-1. At last, the temperature was ramped to 300Â°C at the same rate and kept isothermal for a period of 15 minutes. Each peak shown on the GC- MS spectra has its own retention time and percentage area.
3.3.3 Contact Angle Meter
Raw heavy bio-oil (Table 3.1) was dissolved in warm chloroform respectively and the glass microscope slides with a dimension of 75mm x 25mm were dipped into the respective solutions. The slides were dried and kept for 7 days in desiccators before performing contact angle measurement using contact angle meter. Three readings were taken for each slide in order to get the average value. Contact angle with greater than 90â° indicated the hydrophobic property of the bio-oil.
3.3.4 Dust Deposition Test
Dust deposition test is conducts on all the samples prepared. Initially, a clean aluminium plate is prepared and weighed to obtain the initial weight. Then, the samples are coated onto the plate and the coating is left to dry for an hour. 5g of kernel which acts as the dust is sprinkled onto the plate evenly. After that, the plate is kept in an enclosed area for three hours. After three hours, the three hours, the aluminium plate was hold upside down to detach the dusts. At last, weigh the final weight of the plate. The experiment is repeated for six and nine hours of dusts exposures, for all the samples.
3.3.5 Biodegradability Test
Biodegradability test is conducted on 3 samples of bio-oil (Table 3.1), one on 100ml of raw heavy bio-oil, and the other one with the sample of heavy bio-oil and 1-octacosanol and the last one with the sample of bio-oil, 1-octacosanol and hexamethylenetetramine. Initial dissolved oxygen was read using dissolved oxygen meter. After 5 days, the final dissolved oxygen was read.
3.4 Upgrading of Raw Heavy Bio-oil
In this research, ambient temperature (25Â°C) and pressure (1 atm.) condition is used due to economical and operational considerations.
3.4.1 Addition of 1-Octacosanol
The raw heavy bio-oil is added with different proportions of 1-octacosanol to upgrade its internal properties. Then, the upgraded heavy bio-oil also ran through the same analyses (contact angle, FTIR and GCMS) for the purpose of acquirement and conformation properties as well as the hydrophobic properties of the upgraded heavy bio-oil. The characterization analyses were carried out for the raw bio-oil and upgraded heavy bio- oil so as to distinguish the properties changes between them.
3.4.2 Addition of hexamethylenetetramine as the binder
The most hydrophobic sample obtained from Section 3.4.1 is further added with hexamethylenetetramine to enhance the hydrophobic properties of the heavy bio-oil. Correspondingly, the latter mixture ran through the similar analyses (FTIR, GCMS, contact angle).
At last, the results of characterizations and contact tangle measurements for raw heavy bio-oil (Section 3.3), the heavy bio-oil added with 1-octacosanol (Section 3.4.1) and the mixture as shown in Section 3.4.2 are compared.
Table 3.1 Summary of different mass proportions for sample 1, sample 2 (a), (b) and (c) and sample 3 (a), (b) and (c) at ambient condition.
Raw heavy bio-oil (HBO) (g)
HBO + 1-octacosanol (mg)
Most hydrophobic sample 2 (g)
4.1 Characterization of Heavy Bio-oil before and After Upgrading
The results obtained were compared among the raw heavy bio-oil (sample 1), mixture of heavy bio-oil and 1-octacosanol and the mixture of raw heavy bio-oil (sample 2), mixture of raw heavy bio-oil, 1-octacosanol and hexamethylenetetramine (sample 3).
4.2 Physical properties Analysis using Contact Angle Meter
The observed contact angle of droplets of the sample 1 (Figure 4.1a) on the surface give an angle of less than 90â°, showing that it is hydrophilic. For samples 2 and 3 (Figure 4.1 b and c), both showed a contact angle greater than 90â°, which showed a hydrophobic behaviour. The images in Figure 4.1 showed how the samples of bio-oil formed spherical shape on surface. There were three aspects which influenced the contact angle of a liquid droplet on a surface which was surface tension of the liquid (force of molecules), surface of the solid and surrounding vapour (Koch and Barthlott, 2009).
Figure 4.1 Contact angle, Î¸ of (a) sample 1 (b) samples 2 (a), (b), (c) and, (c) samples 3 (a), (b), (c) on a solid surface.
4.3 Chemical properties analysis using FTIR Spectrometer
The presence of the possible functional groups in a sample can be determined through the infrared spectrometry (Williams and Fleming, 2008). Figure 4.2 showed the absorbance comparison of sample 1, samples 2 (a), (b), (c) and samples 3 (a), (b), (c). Table 4.1 indicated the expected functional groups identified for the three different samples.
Table 4.1 Summary analysis of FTIR for (a) sample 1, (b) sample 2 (a), (b), (c) and (c) samples 3 (a), (b), (c).
Wave number range (cm-1)
Peak wave number (cm-1)
Figure 4.2 FTIR results: absorbance comparison of (a) sample 1, (b) samples 2 (a), (b), (c) and, (c) samples 3 (a), (b), (c).
4.4 Physical Properties Analysis using GCMS
Figure 4.3 showed the components present in the raw heavy bio-oil (sample 1) alone. The heavy bio-oil contains phenol and phenolic compounds mostly (Gengadharan, 2012).
Figure 4.3 GCMS results of (a) sample 1, (b) sample 2 (a), (b), (c), and (c) sample 3 (a), (b), (c).
4.5 Dust Deposition Test
It is expected that the weight of aluminium plates coated with sample 1 (hydrophilic substrate), increases after several hours of exposure to the kernel dusts as the dried kernel dust attached on the top of the plates. However, for the samples 2(c) and 3(c), the difference in weight of the plates showed negative values. This means that the hydrophobic substrates do not attached the hydrophilic dried kernel on top of the plates. (Gengadharan, 2012). The weight of the aluminium pate for hydrophilic substrate (sample 1) is higher than for hydrophobic substrates (sample 2c and 3c) after different hour of exposures.
Table 4.2 Difference in the weight of aluminium plate after different hours of exposure.
Average difference in weight of the aluminium plate
Wfinal- Winitial (g)
Average difference in weight of the aluminium plate
Wfinal- Winitial (g)
Average difference in weight of the aluminium plate
Wfinal- Winitial (g)
Sample 2 (c)
Sample 3 (c)
4.6 Biodegradability Test
Table 4.3 shows the BOD5 values for sample 3 (c) with appropriate dilution. It is expected that the uptake of oxygen of the samples in the water is fast. Thus, the samples are sustainable or 'green'.
Table 4.3 Initial DO, Final DO and BOD5 values for sample 3(c).
Initial DO (mg/l)
Final DO (mg/l)
50 ml of sample 3 (c) without dilution
30 ml of sample 3 (c) + 20 ml dilution water
10 ml of sample 3 (c) + 40 ml dilution water
This study proposed and analysed the conversion of hydrophilic heavy bio-oil to hydrophobic heavy bio-oil by adding external hydrophobic agent, 1-octacosanol and hydrophobic binder, hexamethylenetetramine. It is assumed that the addition of these two chemicals improves the hydrophobic property of the heavy bio-oil. The hydrophobic property of the heavy bio-oil will be confirmed by conducting the contact angle measurement and dust deposition test. Through conducting this research, a new approach emerged to produce sustainable chemicals with hydrophobic behaviour.
From this research, several recommendations are suggested.
The extraction of the heavy bio-oil from the raw bio-oil should be in a fume chamber with good ventilation, since the bio-oil has an acrid smoky smell. Other optional fractionation methods (phase separation by adding aqueous inorganic salt solution or simultaneous addition of hydrophobic polar solvent and aqueous NaOH) should be tried rather than using liquid-liquid extraction alone.
The addition of 1-octacosanol and hexamethylenetetramine to the raw heavy bio-oil should not be limited to three different mass proportions only, but try also wider mass proportions of these chemicals to obtain the best result.
(c) Alternative chemicals should be suggested to replace the 1-octacosanol used in this research as the unit cost for this chemical is very expensive.
(d) Other form of characterizations such as TGA-DSC, XRD and SEM could be conducted for further investigation to enquire thoroughly the characteristics of the upgraded heavy bio-oil.