Energy Conversion and Management 78 (2014) 50–57

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Energy Conversion and Management

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Production and characterization of biodiesel from Camelus dromedarius(Hachi) fat

0196-8904/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.enconman.2013.10.036

⇑ Corresponding author. Tel.: +966 4697118; fax: +966 4675992.E-mail address: hmsbihi@ksu.edu.sa (H.M. Sbihi).

Hassen Mohamed Sbihi a,⇑, Imededdine Arbi Nehdi a, Chin Ping Tan b, Saud Ibrahim Al-Resayes a

a King Saud University, College of Science, Chemistry Department, P.O. Box 2454, Riyadh 1145, Saudi Arabiab Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

a r t i c l e i n f o a b s t r a c t

Article history:Received 16 June 2013Accepted 11 October 2013Available online 16 November 2013

Keywords:Hachi fatTransesterificationAlkali catalystFuel propertiesThermal analysis

Recently, biodiesel has been gaining market share against fossil-origin diesel due to its ecological benefitsand because it can be directly substituted for traditional diesel oils. However, the high cost of the rawmaterials required to produce biodiesel make it more expensive than fossil diesel. Therefore, low-pricedraw materials, such as waste cooking oil and animal fats, are of interest because they can be used to drivedown the cost of biodiesel. We have produced biodiesel from camel fat using a transesterification reac-tion with methanol in the presence of NaOH. The experimental variables investigated in this study werethe temperature (30–75 �C), reaction time (20–160 min), catalyst concentration (0.25–1.5%), and metha-nol/fat molar ratio (4:1–9:1). A maximum biodiesel yield of 98.6% was obtained. The fuel properties ofbiodiesel, such as iodine value, saponification value, density, kinematic viscosity, cetane number, flashpoint, sulfur content, carbon residue, water and sediment, high heating value, refractive index, cloudpoint, pour point, and distillation characteristics, were measured. The properties were compared withEN 14214 and ASTM 6751 biodiesel standards, and an acceptable level of agreement was obtained.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

The world is presently confronted with the twin crises of fossilfuel depletion and environmental degradation, and over the pastdecade, environmental concerns have increased significantlythroughout the world. The excessive use of fossils fuels has led toglobal environmental degradation effects such as the greenhouseeffect, climate change, acid rain, and ozone depletion. In addition,the use of various fossil fuels (petroleum products and coal) hasled to various environmental problems, such as the reduction ofunderground-based carbon energy sources, serious modificationin the Earth’s hydrocarbon surface layer, and subsidence after theextraction of fuel and minerals. The use of these fossil fuels has alsoled to an increase in CO2 levels in the atmosphere.

Alternative energy resources have been proposed, and theyhave the potential to quench man’s ever-increasing thirst forenergy. These alternative energy resources are intended to beenvironmentally friendly and are the main reason for this study.

Biodiesel is one such alternative energy source [1]. The mainadvantages of using biodiesel are its safety, nontoxicity, biodegrad-ability, and sustainability. Biodiesel can also be used in unmodifieddiesel engines [2] and for a variety of others applications as a heat-ing oil [3], fuel in aviation [4], surfactant [5], and lubricant [6]. It

possesses good solvent properties [7] and can be used as a substi-tute for conventional diesel [8] in both blended and pure forms.Biodiesel also produces lower net CO2 emission levels, particulatematter, and carbon monoxide compared with the fossil-originequivalent [9].

Previously, two types of raw materials have been typically usedto manufacture biodiesel, namely, vegetable oils such as sunfloweroil [10], olive oil [11], soybean oil [12], cotton oil [13], hazelnut oil[14], rubber seed oil [15], mahua oil [16], jojoba oil [17], tobaccoseed oil [18], and rapeseed oil [19] and animal fatty acids such aswaste tallow [20], salmon oil [21], mutton tallow [20], bovine fat[22], and lard [23]. The substitution of conventional diesel fuelswith fatty-acid methyl esters already comprises a commercialactivity in many countries. However, the use of biodiesel has notbeen expanded into developing countries, mainly due to the higherprice of biodiesel compared with conventional diesel and the factthat biodiesel production is dependent on expensive high-qualityvegetable oils as the feedstock.

The necessity of using low-cost feedstocks has been recognizedby several research groups, who have conducted various studies onbiodiesel production from animal fat and oil, including beef tallowand lard [20,22,23], either by base- or acid-catalyzed methods. Theuse of waste animal fats for biodiesel production has manyadvantages: (i) there is no competition with the food market; (ii)waste is recycled; (iii) animal fat-based biodiesel has a highercloud point than traditional plant-based biodiesel; (iv) animal

H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57 51

fat-based biodiesel is safe to use in all diesel engines; (v) it has alower cetane number, which reduces emissions of nitrous oxideand particulate matter; and (vi) there is a higher emission savingsfor typical greenhouse gases.

According to statistics from the Food and Agriculture Organiza-tion of the United Nations (FAO), there are approximately 19 mil-lion camels in the world, of which 15 million are found in Africaand 4 million in Asia. According to the Ministry of Agricultureand Water in Saudi Arabia, the camel population of Saudi Arabiais estimated at 400,000 head of Arabian camels or dromedaries. Ca-mel meat is consumed by a large number of Saudis; 40% of redmeat consumption in the kingdom is provided by camels (FAO,2008).

FAO statistics indicate that the average quantity of camel meatproduced in Saudi Arabia was 41,000 tonnes per year between2000 and 2009 and 330,000 tonnes per year around the world. Acamel weighs between 250 and 680 kg, with large mass (25–35 kg) of fat accumulated in the hump, meaning approximately8% of the gross weight of a camel is fat. Therefore, approximately3000 tonnes of waste camel fat are produced each year in SaudiArabia, which translates to a potential to produce approximately3 billion liters of biodiesel. In total, 26,400 tonnes of waste camelfat is available annually from the rest of the world, yielding a po-tential 27 billion liters of biodiesel. Research has shown that thefuel properties of vegetable oils or animal fats can be improvedby transesterification, and this is the method of choice in the cur-rent study.

We have evaluated the use of waste camel fat to produce bio-diesel and have evaluated the practicality of the use of this feed-stock as a source for biodiesel. Biodiesel was prepared fromcamel fat by transesterification of the crude oil with methanol inthe presence of NaOH as a catalyst. As far as we know, camel fathas not yet been investigated for biodiesel production. Optimiza-tion of key reaction parameters, such as the temperature of thereaction, the time required for the reaction, the catalyst concentra-tion, and the molar ratio of methanol to fat for the methanolysis ofmethyl esters of Hachi fat was performed. Furthermore, the com-position of methyl ester and physicochemical properties of fattyacid methyl ester (FAME) were also investigated. The qualities ofthe biodiesel produced from camel fat were tested using the ASTM(American Society for Testing and Materials) D6751 biodiesel stan-dard and the European biodiesel standard EN 14214.

2. Materials and methods

2.1. Materials

Hachi (young camel) fat was collected from a retail butcher’sshop in Riyadh, Saudi Arabia. The fat was melted by slowly heatingto 60–70 �C and was separated from the solid residue. The trans-parent liquid layer was filtered at a reduced pressure, and the ex-tracted fat was stored at 4 �C during the experimental period. Allthe reagents used were of analytical grade and were purchasedfrom Merck (Germany).

2.2. Fatty acid methyl ester analysis

The FAMEs obtained in the transesterification reaction wereanalyzed by gas chromatography using a Shimadzu GC-2014instrument equipped with a flame ionization detector (FID) and anonpolar capillary column Rtx-1 (0.25 mm internal diameter,30 m length, and 0.25 lm film thickness) to obtain the FAME indi-vidual peaks. The detector temperature was 275 �C, and the col-umn temperature was 220 �C. The temperature was held for1 min and then increased at a rate of 15 �C/min to 180 �C and then

increased again at a rate of 1 �C/min to 210 �C and held for 4 min.The carrier gas was helium, which was flowed at 1.41 mL/min. Therun time was 60 min. The FAME peaks were identified by compar-ing their retention times with FAMEs from conventional oils andfrom pure FAME standards (Supelco, USA). The fatty acid methylester peak identification was confirmed by the gas chromatogra-phy-mass spectrometry technique using a Shimadzu GCMS-QP2010 Ultra instrument operating under similar conditions asthose used for the GC-FID. The relative percentage of the fatty acidwas calculated on the basis of the peak area of a fatty acid speciesto the total peak area of all the fatty acids in the oil sample.

2.3. Biodiesel preparation and analysis

2.3.1. Pretreatment – the first step in biodiesel productionThe percentage of free fatty acid (as oleic acid) was calculated

according to ISO 660 (1996). Hachi fat had an acid value of0.96%, which is below the 1% limit for satisfactory transesterifica-tion reactions using an alkaline catalyst [24].

2.3.2. Analytical methodsA 1 g sample of Hachi fat was heated at the reaction temper-

ature in an Erlenmeyer flask equipped with a condenser to pre-vent methanol loss. Then, methanol and basic catalyst (NaOH)were added, and the stirring of the mixture was started (zerotime) using a magnetic stirrer (IKA C-MAG HS7 digital, Staufen,German).

At the end of each test, the mixture was placed at room temper-ature for a few minutes, and 5 mL of HPLC n-hexane was added tothe cooled crude biodiesel. The purity was analyzed by using thesame GC apparatus cited before. The analysis of the biodiesel foreach sample was carried out by taking 0.5 mL of a mixture of crudebiodiesel with hexane and 0.02 g of methyl salicylate dissolved in0.5 mL of n-hexane, which was added as reference, and injecting1 lL of this solution into the GC. The purity of the biodiesel sam-ples was calculated based on the area of FAME over the referenceaccording to the following equation [25]:

Purityð%Þ ¼ ðarea of FAMEÞ � ðweight of referenceÞðarea of referenceÞ � ðweight of biodiesel sampleÞ� CF � 100

CF: Correction factor

The methyl esters were synthesized in a conical flask equippedwith a magnetic stirrer (IKA C-MAG HS7 digital, Staufen, German)and a reflux condenser. A 10 g sample (1% of the weight of the fat)of sodium hydroxide was dissolved in 214.4 g of methanol andadded slowly with constant stirring (for 2 h at 65 �C) to 1000 g ofmelted Hachi fat (with a 6:1 M ratio of alcohol to fat). The mixturewas transferred to a separator funnel and then settled at roomtemperature for a minimum period of 12 h when a distinct separa-tion of layers was visible. The upper transparent layer consisted ofbiodiesel, and dark brown glycerol formed the bottom layer. Afterdraining off the glycerol, petroleum ether was added, and the toplayer was washed gently with five different volumes of distilledwater to remove residual sodium hydroxide, glycerol, methanol,and soap. A few drops of sulfuric (H2SO4) acid were added for thethird washing to neutralize the remaining soap and other catalyticimpurities. The washed layer was dried over anhydrous sodiumsulfate (Na2SO4), and the ether was removed under vacuum usinga rotary evaporator (R-210 BUCHI, Flawil, Switzerland) in a 50 �Cbath water.

The fuel properties of the methyl ester were evaluated accord-ing to the American Society for Testing and Materials (ASTM)standard methods for pour point (ASTM D 97), gross heat value

52 H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57

(ASTM D 4809), cloud point (ASTM D 2500), density (ASTM D5002), kinematic viscosity (ASTM D 445), flash point in an openvase (ASTM D92), sulfur content (ASTM D 4294), distillation curve(D 1160), water and sediment (ASTM D 2709), and carbon residue(ASTM D 4530). The refractive index of the biodiesel was deter-mined using an ABBe 60 (Bellingham + Stanley Limited, England)refractometer. The iodine value was calculated [26] based on 1HNMR spectra of the Hachi fat. The saponification (ISO 3657) valuewas determined according to the International Organization forStandardization ISO standard. The cetane number (CN) was calcu-lated [27] from the following equation by using the saponificationvalue (SV) and iodine value (IV):

CN ¼ 46:3þ 5458=SV� 0:225IV

The FTIR spectrum was recorded on a Bruker Tensor 27 FTIR spec-trometer equipped with an ATR sampling accessory with a remov-able ZnSe crystal. The spectrum was collected from 64 scans witha spectrum resolution of 4 cm�1. The average spectrum fromtriplicate analysis in the range of 4000–400 cm�1 was treatedchemometrically using Opus 6.5 Software (Bruker, Germany).

The thermal characteristics of the Hachi fat and the productmethyl esters were measured using a TGA-50 thermogravimetricanalyzer (Shimadzu, Japan). The air flow rate was 100 mL/min.The Hachi fat or biodiesel product samples (approximately 5 mg)were weighed in open aluminum pans. The sample pan was thenplaced inside the calorimeter. The temperature was increased from25 to 600 �C at a rate of 10 �C/min.

3. Results and discussion

3.1. Fatty acid characterization

These analyses showed clearly that Hachi fat and the producedbiodiesel gave high amounts of saturated esters with a satu-rated:unsaturated mass ratio of 1.64. This composition explainsthe poor low-temperature characteristic of Hachi biodiesel, whichtends to solidify during the winter in cold climate regions. Table 1presents the quantitative composition of the biodiesel fatty acidmethyl esters (FAMEs) from Hachi. A typical characteristic of ani-mal fat is the high amount of saturated acids represented by thepresence of palmitic acid (C16:0; 34.6%), stearic acid (C18:0;11.07%), and myristic acid (C14:0; 9.82%). Oleic acid (C18:1) wasthe dominant unsaturated fatty acid (25.44%).

Table 1Fatty acid composition of the Hachi fat.

Fatty acid Composition (%)

SaturatedC12:0 0.50C13:0 0.06C14:0 9.82C15:0 2.24C16:0 34.6C17:0 3.66C18:0 11.07C20:0 0.2Total saturated 62.16

UnsaturatedC14:1 0.52C16:1 9.30C18:1 25.44C20:1 0.40Total unsaturated 37.83Saturated/unsaturated 1.64

3.2. Alkali-catalyzed transesterification process of Hachi fat

During the optimization process, the factors affecting the con-version efficiency of the methyl esters (Fig. 1), such as the reactiontemperature, reaction time, catalyst concentration, and methanol-to-oil ratio with a constant agitation speed (750 rpm), were inves-tigated. The conversion efficiency is defined as the methyl esteryield of the process represented in terms of percentage.

3.2.1. Effect of reaction temperatureThe temperature influences the reaction rate and the yield of

the biodiesel product. A stronger reaction can decrease the viscos-ities of oils or fats and result in an increased reaction rate and ashortened reaction time. The study of the effect of temperature isvery interesting for alkali-catalyzed transesterification reactions.Fig. 2 shows the variation in Hachi fat conversion at different reac-tion temperatures in the range of 30–75 �C with a methanol/oilmolar ratio of 6:1, a catalyst amount of 1% NaOH, and a reactiontime of 120 min. The optimal yield (98.6%) of biodiesel was ob-tained at 65 �C. A previous study by Leung and Guo [28] showedthat temperatures higher than 50 �C had a negative impact onthe product yield for neat oil but had a positive effect for wasteoil with higher viscosities. Hence, at temperatures higher than65 �C, methanol evaporates and causes lower yield (91.2% and90.2%) at reaction temperatures of 70 �C and 75 �C (Fig. 2).

Bhatti et al. [20] reported in their study that the highest yieldsof biodiesel from chicken and mutton tallow, using acid (H2SO4) asa catalyst, were obtained at 50 and 60 �C, respectively. When usingKOH as a catalyst at 30 �C, they found an optimal yield of 88.14%and 78.33% for chicken and mutton tallow, respectively. These dif-ferent temperatures for the obtained maximum yields of biodieselfrom Hachi fat compared with other fats (chicken and mutton tal-low) were due to the difference in their fatty acid composition. In-deed, Hachi fat contained higher percentage of saturated fatty acidthan chicken and mutton tallow, and therefore, it required a higherreaction temperature.

3.2.2. Effect of reaction timeThe reaction time is one important factor that affects the alkali-

catalyzed transesterification. The triacylglyceride conversion in-creased as the reaction time increased. Fig. 3 shows the effect ofthe reaction time on Hachi fat conversion by alkali-catalyzedtransesterification with a catalyst amount of 1% NaOH, a metha-nol/fat molar ratio of 6:1, and a reaction temperature of 65 �C. Asthe reaction time increased, the Hachi fat conversion increasedand was over 90% at 40 min. The highest yield (98.6%) of biodieselwas obtained at 120 min. After 120 min, the accelerated Hachi fatconversion decreased gradually (Fig. 3), and we observed a largeamount of soap.

3.2.3. Effect of alkali catalyst amountThe results obtained in our investigation are shown in Fig. 4.

The alkali catalyst concentration varied from 0.25% to 1.5% byweight of Hachi fat with a methanol/fat molar ratio of 6:1, a reac-tion temperature of 65 �C, and a reaction time of 120 min. Whenthe catalyst concentration increased from 0.25% to 1%, the conver-sion to methyl ester increased to 98%. Nevertheless, when the cat-alyst concentration exceeded 1%, the conversion to methyl esterdecreased due to the reaction of alkali catalyst with more triglyc-erides (saponification), thereby causing the formation of moresoap. When the catalyst concentration (1.5%) was excessive, thesaponification was more serious.

3.2.4. Effect of methanol/oil molar ratioOne of the most important variables affecting the conversion to

methyl esters is the molar ratio of methanol to oil or fat. The

CH2

CH

CH2

O

O

O

C

C

C

R

R

R

O

O

O

CH2

CH

CH2

OH

OH

OH

CH3OH

CH3 O C RO

CH3 O C RO

CH3 O C RO

3+ +

1

2

3

1

2

3

Triglyceride Methanol Methyl estersGlycerol

Fig. 1. Conversion of triglyceride to fatty acid methyl esters.

Fig. 2. Effect of temperature on Hachi fat conversion.

Fig. 3. Effect of reaction time on Hachi fat conversion.

Fig. 4. Effect of alkali catalyst amount on Hachi fat conversion.

H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57 53

stoichiometric molar ratio of methanol to Hachi fat for completetransesterification of the fatty acids in the oil to methyl esters is3:1. However, in practice, a higher molar ratio is employed to shiftthe reaction equilibrium toward the product side and producemore methyl esters.

In general, the molar ratio is associated with the type of catalystused. Previous investigations have shown that an acid-catalyzedtransesterification requires a high molar ratio of methanol to oil(30–150:1), whereas a molar ratio of methanol to oil of 6–15:1 isusually used in alkali-catalyzed systems [29]. Fig. 5 reflects the ef-fect of the molar ratio of methanol to fat on the conversion of Hachifat with a catalyst amount of 1% NaOH, a reaction temperature of65 �C, and a reaction time of 120 min. As shown in Fig. 5, the con-version was increased considerably with an increasing methanolamount, and the molar ratio was very close to 6:1; the maximumconversion achieved was 98.6%. However, the conversion tomethyl esters was decreased with the increase in methanol, andthe conversion was 89% at 9:1. Rashid and Anwar [30] alsoreported that a further increase in the alcohol used in the transe-sterification of rapeseed oil beyond the optimum ratio would resultin a reduced ester yield. When too much alcohol is used in transe-sterification, the polarity of the reaction mixture is increased, thusincreasing the solubility of glycerol back into the ester phase andpromoting the reverse reaction between glycerol and ester or glyc-eride, thereby reducing the ester conversion.

3.3. Infrared spectrometry

The FTIR spectrum of Hachi methyl ester is shown in Fig. 6. IRspectra showed the main feature for a band of fatty acid methyl es-ters at 1746 cm�1 (ester C@O stretch). The band observed in thebiodiesel spectrum at 1163 cm�1 was attributed to methyl groupsnear the carbonyl groups, the bands at 1465 cm�1 and 1377 cm�1

corresponded to asymmetric and symmetric CH3 deformationvibrations, respectively, and the band at 1163 cm�1 correspondedto the stretching vibration of the CAO ester group. This result re-flected the conversion of triglycerides to methyl esters and showed

Fig. 5. Effect of methanol/fat ratio on Hachi fat conversion.

Fig. 6. IR spectrum of the Hachi biodiesel.

54 H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57

the purity of biodiesel with an absence of glycerol and excessmethanol (as there are no bands above 3200 cm�1 correspondingto OAH stretching).

Fig. 8. TG/DTG curves of Hachi biodiesel under nitrogen.

3.4. Thermal analysis

Thermogravimetric (TG) and derivative thermogravimetricanalysis (DTG) were used to provide information on the thermalbehavior of Hachi-origin methyl esters. The thermal stability andvolatility characteristics influence the ignition quality of fuels[31]. Figs. 7 and 8 show the temperature scan of a Hachi biodieselsample in dry air and in nitrogen atmosphere heating. These fig-ures show the decomposition and weight loss of the biodiesel sam-ples and derivative weight loss at the corresponding temperatures.The changes in weight occurred because of vaporization and/orcombustion (or pyrolysis) of the Hachi methyl esters.

Heating Hachi biodiesel under dry air consisted of three steps(Fig. 7). In the first phase, only a minimal weight change wasobserved. The thermogram shows that the 2.6% weight loss ofthe Hachi biodiesel sample in the dry air atmosphere occurs atapproximately 100 �C (Fig. 7). A rapid weight change was also

Fig. 7. TG/DTG curves of Hachi biodiesel under dry air.

observed during the second phase. The maximum degradation rateoccurred at a temperature of 201.5 �C, where the rate of weight de-crease increased to a maximum. Lower rates of weight loss wereobserved at higher temperatures. The curve flattened at 300 �C,indicating no further conversion occurred after this temperature.Throughout, vaporization and/or combustion of the Hachi biodieselwere also occurring.

Fig. 8 shows the temperature scan of a Hachi biodiesel sampleheated under a nitrogen atmosphere. The TG/DTG curves of theHachi biodiesel in nitrogen presented the same thermal steps asin dry air with an increase in the maximum decomposition tem-perature to 210.9 �C due to the vaporization and/or pyrolysis ofthe Hachi methyl esters.

3.5. Characterization of biodiesel

Kinematic viscosity is a significant fuel characteristic that af-fects the extent of both fuel fluidity and atomization, particularlywhen the liquid fuel is used at a low temperature. This means thata greater kinematic viscosity can cause pumping difficulties and

Fig. 9. Kinematic viscosities of Hachi biodiesel.

H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57 55

improper fuel injection. The limits of kinematic viscosity forbiodiesel and diesel fuel are in the range of 1.9–6.0 mm2/s and3.5–5 mm2/s, respectively, according to the ASTM standards andEuropean petrodiesel standard. The experimental kinematicviscosity for Hachi methyl esters was related to the fatty acid com-position, which increases with the proportion of saturated fattymethyl esters. As a comparison to other animal fat–origin biodie-sels such as tallow (5.35 mm2/s), lard (5.08 mm2/s), and poultry(6.86 mm2/s), the viscosity test showed that the kinematic viscos-ity of pure Hachi biodiesel (3.43 mm2/s at 40 �C) was lower thanthose of the animal fat–origin biodiesels and within the limitsspecified in the biodiesel standards. The viscosities of Hachi biodie-sel were measured at different temperatures and are representedin Fig. 9. From the figure, it can be seen that the viscosity rapidly

Table 2Fuel properties of Hachi methyl esters in comparison with biodiesel standards.

Property Unit An

Saponification value mg of KOH/g 20Iodine value g I2/100 g 65Flash point �C 15Cetane number 58Density at 15.6 �C g/cm3 0.8Viscosity at 40 �C mm2/s 3.3Refractive index at 23 �C 1.4Pour point �C 15Cloud point �C 12High heating value MJ/kg 39Sulfur content wt.% 0.0Carbon residue wt.% 0.0Water and sediment % 0Distillation temperature �C

10% 3020% 3230% 3340% 3350% 3360% 3570% 3580% 3590% 36

Metals contentCalcium lg/g <1Magnesium lg/g <1Potassium lg/g <1Sodium lg/g 6

a Calcium & magnesium (combined).b Sodium & potassium (combined).

decreased as the temperature increased. The Hachi biodiesel vis-cosity was higher at a low temperature (4.5 mm2/s at 30 �C) butwithin the ASTM range. The value decreased at higher tempera-tures until it was less than 2 mm2/s starting at 70 �C.

The Hachi methyl esters had a density of 0.871 g/cm3 at 15.6 �C.The density value found in this study was comparable to the valuerecommended in the EN 14214 and ASTM 6751 biodiesel standard.Hachi biodiesel is acceptably close to petroleum diesel.

The concentration of sulfur in the Hachi methyl ester sampleswas measured using ASTM D 4294. As depicted in Table 2, unlikeconventional petrodiesel fuels (which have a sulfur content of0.05%), the biodiesel produced from Hachi fat in the present studyhad a negligible sulfur content (0.031%). A low sulfur level isknown to help both engine life and the environment.

Carbon residue is one of the most important qualities ofbiodiesel, as it gives an indication of the coke-forming tendencyof the fuel. The carbon residue of the pure Hachi biodiesel was0.05 wt.%. This value was lower than 0.3 wt.% (maximal permittedvalue, EN 14214) and within the upper limit for the US biodieselnorm (ASTM D6751 of 0.05 wt.%) (Table 2).

Two important parameters for low-temperature applications ofa fuel are the cloud point (CP) and the pour point (PP). The CP is thetemperature at which wax first becomes visible when the fuel iscooled. The PP is the lowest temperature at which the oil specimencan still be moved and at which the amount of wax precipitatingout of solution is sufficient to gel the fuel.

Animal fat-based biodiesel has a higher cloud point (tallowmethyl esters: CP = 17 �C and PP = 15 �C) than traditional plant-based biodiesel (methyl ester of peanut oil: CP = �8 �C andPP = 0 �C) due to the high percentage of saturated fatty acid methylesters. Hachi methyl esters had a higher CP and PP compared withpetroleum diesel, at 12.7 �C and 15.6 �C, respectively (Table 2).

The heating value is the enthalpy released after the completecombustion reaction of fuel at a constant pressure or volume.The higher the heating value of the fuel, the lower the fuelconsumption required to obtain the same engine power output.

alysis result ASTM D6751 EN 14214

2.3.3 120 max8 130 min 120 min.7 47 min 51 min71 0.87–0.90 0.86–0.909 1.9–6.0 3.50–5.0046.5 �15 to 10.7 �3 to 12.5231 0.05 max 0.05 max5 0.05 max 0.3 max

0.05% max

482465780 360 max

5 maxa 5 maxa

5 max b 5 max b

56 H.M. Sbihi et al. / Energy Conversion and Management 78 (2014) 50–57

Monyem and Van Gerpen [32] found that a pure biodiesel had aheating value lower than that of ASTM No. 2D diesel by approxi-mately 12.7–14.7%. The heating values of the biodiesel producedfrom Hachi fat, commercial biodiesel from waste cooking oil, andthe ASTM No. 2D diesel fuel were 39.5 MJ/kg, 40.11 MJ/kg, and46.16 MJ/kg, respectively. The Hachi fat biodiesel contained1.8 wt% long-chain (C20 and other fatty acids) fatty acids. In con-trast, general biodiesel fuels produced from waste cooking oil, veg-etable oils, or animal fats are primarily composed of unsaturatedfatty acids consisting of C18 carbon chains such as oleic acid andlinoleic acid, as shown in Table 1. Hence, Hachi fat biodiesel hasthe same heating value as that of commercial biodiesel from wastecooking oil, whereas the ASTM No. 2D diesel has a higher heatingvalue than the other two biodiesel fuels.

The fuel flash point is the temperature at which it will ignitewhen exposed to a flame or spark. The flash point of biodiesel ishigh (Table 2), which makes it safe for transportation purposes[29]. Biodiesel must have a flash point higher than 120 �C. The flashpoint of the biodiesel sample produced in this study was 158 �C.

The cetane number (CN) is the ability of fuel to ignite quicklyafter being injected. A better ignition quality of the fuel is alwaysassociated with higher CN values. This is one important parameterthat must be considered during the selection of methyl esters foruse in biodiesel. The CN of biodiesel varies widely in the range of48–67 depending upon various parameters, including the oil-pro-cessing technology used and the climatic conditions where thefeedstock is collected [33]. CN affects a number of engine perfor-mance parameters, such as combustion, stability, drivability, whitesmoke, noise, and the emission of CO and HC [2,29]. The CN ofHachi methyl ester was calculated on the basis of the SV and IV.The SV and IV were 202.69 and 45.9, respectively (Table 2). TheCN of the biodiesel sample produced in this work was 62.9(Table 2). According to Ramos et al. [34], high CNs were observedfor esters of saturated fatty acids such as palmitic (C16:0) and stea-ric (C18:0) acids and monounsaturated fatty acids (C18:1). Hachibiodiesel, rich in these compounds (Table 1), had a high CN.

The refractive index of Hachi methyl esters at 23 �C was 1.446.The T90 distillation temperature was high (360 �C) because of thehigh concentration of saturated fatty acid methyl esters in Hachibiodiesel, but the T90 value was still within the acceptable rangeof the D1160 standard (360 �C max). ASTM D 2709 was used tomeasure the total amount of free water and sediment in Hachi bio-diesel. Water and sediment tests showed no water or sediment inthe biodiesel produced from Hachi fat.

4. Conclusion

The results of this study show that low-cost Hachi fat can serveas a possible alternative source for biodiesel production. Hachi fatwas extracted and chemically converted via an alkaline transeste-rification reaction to fatty acid methyl esters. The conversion was98.6% at 65 �C with a 6:1 M ratio (methanol to fat) for NaOH (1%fat weight)-catalyzed transesterification.

This study has shown that ten of the properties (kinematic vis-cosity, density, cetane number, flash point, sulfur contents, waterand sediment, carbon residue, high heating value, T90 distillationtemperature, and metal content) that were evaluated for the dieselconform to the ASTM and EN standards values, with the sole disad-vantages being a poor cold point value (12.7 �C) and pour point va-lue (15.6 �C), meaning consumers in cold climates will need to takeprecautions during the winter when using Hachi biodiesel.

From these results, it is concluded that waste camel fat can beutilized as an alternative feedstock for biodiesel production,replacing high-cost refined vegetable oil feedstocks and increasingglycerol production. Until recently, the commercial production and

consumption of glycerol were generally considered a fair barome-ter of industrial activity because glycerol is used in such a largenumber of industrial processes.

Considering Somalia as an example country, there is a nationalcamel herd of 7 million head. If 10% of the camel herds are pro-cessed for biodiesel per year, more than 6 million liters of biodieselcan be produced. This figure, according to the National BiodieselBoard’s statistics, is double the total biodiesel production fromthe United States (2.66 million liters/year, all feedstocks, 2008).Somalia could also benefit from the production of biodiesel dueto the commercial aspects of the glycerol production.

Acknowledgements

The authors would like to extend their sincere appreciation tothe Deanship of Scientific Research at King Saud University for itsfunding of this research through the Research Group Project No.RGP-VPP-243.

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