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Momordica charantia Seed Oil Methyl Esters: KineticStudy and Fuel PropertiesUmer Rashid a , Junaid Ahmad b c , Robiah Yunus a , Muhammad Ibrahim d , Hassan Masood e
& Azhari Muhammad Syam a fa Institute of Advanced Technology , Universiti Putra Malaysia , 43400 , UPM Serdang ,Selangor , Malaysiab Department of Industrial Chemistry , Government College University , Faisalabad , 38000 ,Pakistanc Chemical Engineering Department , Universiti Teknologi PETRONAS, Bandar Seri Iskandar ,Tronoh , 31750 , Perak , Malaysiad Department of Environmental Sciences , Government College University , Faisalabad ,38000 , Pakistane Department of Chemical and Environmental Engineering , Universiti Putra Malaysia ,43400 , UPM Serdang , Selangor , Malaysiaf Department of Chemical Engineering, Faculty of Engineering , University of Malikussaleh ,Lhokseumawe , 24351 , Nanggore Aceh Darussalam , IndonesiaAccepted author version posted online: 20 Sep 2013.
To cite this article: International Journal of Green Energy (2013): Momordica charantia Seed Oil Methyl Esters: Kinetic Studyand Fuel Properties, International Journal of Green Energy, DOI: 10.1080/15435075.2013.823090
To link to this article: http://dx.doi.org/10.1080/15435075.2013.823090
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Momordica charantia Seed Oil Methyl Esters: Kinetic Study and Fuel Properties Umer Rashida,*, Junaid Ahmadb,c, Robiah Yunusa, Muhammad Ibrahimd, Hassan Masoode and
Azhari Muhammad Syama,f
aInstitute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
bDepartment of Industrial Chemistry, Government College University, Faisalabad-38000, Pakistan
cChemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Tronoh 31750, Perak, Malaysia
dDepartment of Environmental Sciences, Government College University, Faisalabad-38000, Pakistan
eDepartment of Chemical and Environmental Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
fDepartment of Chemical Engineering, Faculty of Engineering, University of Malikussaleh, Lhokseumawe 24351, Nanggore Aceh Darussalam, Indonesia
*To whom correspondence should be addressed.
E-mail: [email protected] Tel.; +60-603-8946-7393; Fax: (+60) 03 89467004; Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
ABSTRACT
Due to growing concerns such as increasing energy demand and the environmental issues related
fossil energy problems caused by consumption of fossil energy, it is needed to focus on non-
edible oils for biodiesel production. In the present research work, the seed oil of Momordica
charantia (M. charantia) was for the first time appraised as possible non-edible oil for synthesis
of biodiesel. M. charantia has oil content (36.10±4.20%), high acid value (1.82 mg KOH g-1)
and its oil enable base-catalyzed transesterified for biodiesel production after acid pre-treatment.
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It was transesterified under standard conditions at 6:1 molar ratio of methanol to oil; sodium
methoxide (1.00% wt in relation to oil mass) as a catalyst; 60 ℃ reaction temperature and 90 min
of reaction time. At optimum conditions biodiesel yield of 93.2% was acquired. The reaction
followed first order kinetics. The activation energy (EA) was 254.5 kcal mol-1 and the rate
constant value was 1.30 × 10-4 min-1 at 60 °C. Gas chromatography (GC) investigation of M.
charantia seed oil methyl esters (MSOMEs) depicted that the fatty acid composition comprises a
high proportion of mono-unsaturated fatty acids (64.11±5.02%). MSOMEs were also
characterized using Fourier Transform Infrared (FT-IR) and 1H Nuclear Magnetic Resonance
(1H-NMR) spectroscopy. The tested fuel properties of the MSOMEs, except oxidative stability,
were conformed to EN 14214 and ASTM D6751 standards. The low value oxidative stability of
MSOMEs can be solved by adding antioxidants additives. In summary, M. charantia oil has
potential as non-edible raw material for biodiesel production.
Keywords: Momordica charantia seed oil; Methanolysis; Kinetic study; GC; 1H-NMR; FT-IR;
Fuel properties
INTRODUCTION
The gradual exhaustion of different petroleum reserves and the need for alternate energy sources
arose. Serious environmental problems e.g. the widespread and intensive use of petroleum-fuels
arises global warming (Nakpong and Wootthikanokkhan, 2010; Ahmad et al., 2013). Thus, the
concern for environmental protection is increasing globally with worldwide attention for
conservation of non-renewable natural resources (Liu et al., 2008; Anwar et al., 2010). Biodiesel
as an alternative source is reported to show many advantages as compared to conventional
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(petroleum) diesel and these include, their extraction from renewable feedstocks, superior
lubrication property and biodegradation, lesser toxicity (nature of feedstock), displacement of
imported petroleum, higher flash point, and a reduction in most of the exhaust emissions (Moser
and Vaughn, 2010; Rashid et al., 2011). Moreover, biodiesel is considered as green fuel because
it does not contain any sulphur, aromatic hydrocarbons and metals (Çaynak et al., 2009).
Demirbas (2009) defined biodiesel as a mixture of mono-alkyl esters (long chain fatty acids)
derived from a renewable lipid feedstock may be vegetable oil or animal fat. The production is
achieved through transesterification or alcoholysis, which is used to reduce the high viscosity of
triglyceride (Meher et al., 2006). The vegetable oils or animal fats react with an alcohol in the
presence of strong base catalyst (NaOH or KOH). This reaction yields a mixture of methyl esters
along with a co-product called glycerol or glycerine (Ramadhas et al., 2005; Rashid et al., 2012;
Li et al., 2012). The properties of resulting biodiesel are quite similar as that of petroleum-based
diesel fuel (Kusdiana and Saka, 2004).
Many papers have been published on the kinetics of transesterification, biodiesel properties and
its application in diesel engine (Jain and Sharma, 2010). The studies are particularly performed
to investigate the kinetics reaction parameters. These parameters then may be used to predict the
extent of chemical reaction at given time under specific reactions conditions (Darnoko and
Cheryan, 2000). Earlier, Noureddini and Zhu (1997) reported that only a few published papers
are on kinetics of transesterification of simple esters which involved sodium hydroxide as the
catalyst. A kinetics study using heterogeneous catalysis transesterification is reported in terms of
the efficiency and economical aspects (Chantrasa et al., 2011). They also reported on the
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predominance of the hydrotalcite catalyst compared to other heterogeneous ones. According to
Li and Rudolph, (2008) and Verziu et al. (2008), a few compounds are utilized as heterogeneous
catalyst for the biodiesel production, particularly Magnesium Oxide (MgO) and Calcium Oxide
(CaO) particularly attracted some researchers’ interest to conduct further investigation on
kinetics of transesterification. Other solid catalyst use is Amberlyst resin, as reported by Pappu et
al. (2011). In their work, Amberlyst 15 was applied as a catalyst for studying the kinetic models
of methyl stearate transesterification with n-butanol as the excess reactant.
The feedstock of biodiesel production in different regions varies according to geographical
location and climatic conditions. For example, canola/rapeseed is mostly used in Europe, palm
oil in tropical countries; soybean oil and animal fats are mainly used in the United States
(Mittelbach and Remschmidt, 2004; Knothe et al., 2005; Moser, 2009). The supply of these oils
is short in many countries. It can pose a threat to food production which eventually leads to
higher food prices. Therefore, it is necessary to explore non-edible oils as the raw material of
biodiesel (Wen et al., 2010; Rashid et al., 2011). Modern day researches are concentrates on the
switch of basestock from edible to non-edible oils for sustainable biodiesel production without
affecting the food security (Demirbas, 2008; Adelbowala et al., 2012). New and low cost non-
edible oil crops may be identified for the production of economical oils suitable for biodiesel
production (Kafuku and Mbarawa, 2010).
Bitter gourd or Chinese melon (Momordica charantia), is a plant belongs to Cucurbitaceae
family and is extensively used as tropical crop in many Asian countries as vegetable and a
medicine (Prashantha et al., 2009). Normally, it is grown as an annual crop. However, it is
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frequently cultivated throughout the year in mild, frost-free winter’s areas. In the plain areas, the
summer season crop is sown from January to June (Singh et al., 2006). M. charantia is
commonly utilized in various industries e.g. in the decolourisation and removal of dyes in the
textile industry. The removal of phenolic compounds from effluents in different industries has
great possibility to become an important industrial crop. Oil extracted from M. charantia showed
good drying characteristics due to high saponification value and low acid value, presence of a
high amount of conjugated octadecatrienoic acids, moderate iodine value and the low set-to-
touch drying time (Prashantha et al., 2009); therefore, it has its application as “drying oil” in
paints, coatings, and inks industries (Chang et al., 1996). However, the potential of bitter gourd
oil as a feedstock for biodiesel production is still unidentified. The main objective of the current
research is to explore the potential of non-edible oil of M. charantia seeds for biodiesel
production. Furthermore, the produced biodiesel is characterized using GC, 1H-NMR, FT-IR and
evaluated the fuel properties of the biodiesel produced from M. charantia oil.
MATERIAL AND METHODS
Momordica charantia seeds were obtained from the Ayub Agriculture Research Institute
(AARI), Faisalabad, Punjab, Pakistan. The seeds were cleaned manually to remove all extra
matter (i.e. dust, dirt and immature broken seeds). All chemicals used in the experiments
included methanol, sodium methoxide, isopropanol, phenolphthalein (1% in isopropanol), N,O-
Bis(trimethylsilyl) trifluoroacetamide and reagents were analytical reagent (AR) grade and
purchased from Merck Chemical Company (Darmstadt, Germany). Pure standards of fatty acid
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methyl esters (FAMEs) i.e. C16:0; C18:0; C18:1; C18:2; C18:3 were obtained from Sigma
Chemical Company (St. Louis, MO, USA).
Momordica charantia seeds (1000 g) were crushed using a commercial grinder and fed to a local
extractor. M. charantia oil obtained was extracted from seeds by using electric oil expeller. The
oil after extraction was subjected to filtration for purification using filtration apparatus.
Pretreatment of M. charantia oil was done as per previous reported method by Rashid et al.
(2013). Esterification was continued until the acid value was less than 1%.
A one step of reaction was performed using the following method; firstly, M. charantia oil was
poured into the three necks round-bottomed flask and heated to the specified temperature. Once
the temperature of M. charantia oil was achieved, excess reactant (methanol) and catalyst were
simultaneously added into the reaction. Maintain the reaction temperature as specified. The
reactor was equipped with a thermometer, a sampling port and a reflux condenser under
atmospheric condition as per our previous study (Yunus et al., 2002) under a constant stirring
rate (650 rpm). Six sets of kinetics data were collected for three different reaction temperatures,
namely 30°C, 45°C, and 60°C, respectively. The sample was collected at the specified reaction
time. After the reaction, the mixture was allowed to cool down and equilibrate resulting in
separation of two phases. Subsequent to separation of the two layers by sedimentation the upper
methyl esters layer was purified by distilling the residual methanol at 70 °C and remaining
catalyst was removed by successive rinses with hot distilled water. Finally, the residual water
was removed with Na2SO4, followed by filtration (Rashid and Anwar, 2008). Thus, the samples
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were stored in an ice bath to avoid further reaction before the gas chromatography analysis was
conducted. The yield of biodiesel was calculated as;
100reactionin used oil of gramsproduced esters methyl of grams (%) biodiesel of Yield ×=
(1)
The gas chromatography samples preparation and analysis was performed base on the developed
GC method by Yunus et al. (2002) was the following; approximately 0.03±0.005 g of sample
was weighed in a 1.5 ml vial and diluted with 1.0 ml of ethyl acetate. The sample was swirled for
few minutes to dissolve the mixture. N,O-Bis(trimethylsilyl) trifluoroacetamide, 0.5 ml, was then
added to the mixture, swirled and finally transferred to a water bath at 40°C for 10 min. The GC
analysis was performed on GC Agilent 6890 series equipped with FID detector and HT5, (SGE
International, Australia) column (12m × 0.53 mm, and 0.15μm ID). Hydrogen at 26.7 ml/min
was used as a carrier gas with split ratio of 1:1. The oven temperature was set at an initial
temperature of 80°C, held for 3 min, increased at 6°C/min to 340°C and held for another 6 min.
The injector and detector temperatures were 300°C and 360°C, respectively (Yunus et al., 2002).
The FTIR spectrum of MSOMEs was recorded by inserting a drop of MSOMEs between
diamond-composite FTIR-ATR sample holding plates on a Bruker Alpha FT-IR spectrometer
(Bruker, Germany). The FTIR-ATR spectra were obtained by averaging 10 scans at 350-6000
cm–1 with a resolution of 2 cm–1 using Opus 6.5 Software (Bruker). A spectrum from the
diamond-composite plates was recorded as a background. NMR spectra were obtained on a
Varian (Palo Alto, CA, USA) VNMR spectrometer operating at 500 MHz (1H-NMR) with
CDCl3 as solvent.
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The fuel properties of the MSOMEs were determined following ASTM and EU methods: cloud
point (ASTM D2500), pour point (ASTM D97), kinematic viscosity (ASTM D445), oxidative
stability (EN 14112), cetane number (ASTM D6890), cold filter plugging point (ASTM D6371),
ash content (ASTM D874), flash point (ASTM D93), density (ASTM D5002), sulphur content
(ASTM D4294), copper strip corrosion (ASTM D130), acid value (ASTM D974), free and
bound glycerol (ASTM D 6584), methanol contents (EN 14110) and monoglyceride, diglyceride
and triglyceride contents (EN 14105). Triplicate determinations were performed for every
experiment and the data are presented as mean ± standard deviation.
RESULTS AND DISCUSSION
Chemical Properties of Momordica charantia Oil
Prior to base catalyzed transesterification, the acid value of Momordica charantia (M.
charantia) oil was 0.42 mg KOH g-1. The saponification and peroxide values of M. charantia oil
were 185.15 mg KOH g-1 and 4.99 m.eq kg-1, respectively. Although, iodine value of the M.
charantia oil was calculated as 124.09 g I2 100g-1.
Kinetic Study
Momordica charantia seed oil had used as the feedstock of transesterification in performing the
kinetics study of the reaction. The progress of transesterification of M. charantia oil at various
temperatures is shown in Figure 1.
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The kinetics study and mechanism of transesterification reaction will reflex the reaction rate
constant, order of reaction and Arrhenius activation energies. As many researchers have reported
that the whole mechanism of transesterification reaction occur under three step wises reaction as
indicated by equation (2) to (4). Each intermediate step of reaction uses one mole of alcohol to
react with n-glyceride compound, which further, produce one mole of alkyl ester (Diasakou et
al., 1998; Yunus and Azhari, 2011). Due to the entire steps of reaction produce methyl ester
compound, for that reason, all the intermediate compounds e.g. monoglyceride and diglyceride
can be negligible and over all reaction conversion as one step described in equation (5).
TG + MeOH DG + ME (2)
DG + MeOH MG + ME (3)
MG + MeOH GL + ME (4)
TG + 3MeOH 3ME + GL (5)
where TG, DG, MG, GL and ME denote triglyceride, diglyceride, monoglyceride, glycerol and
methyl ester.
The effect of temperature on the transesterification of M. charantia oil has been studied in the
present work. Since the oil is naturally liquid at room temperature (25°C), the minimum
temperature selected in this work is 30°C. Below 30°C, the endothermic behaved reaction is not
going on well or taking a longer time for the completion. The maximum temperature studied was
60°C in order to avoid much lost of methanol into atmosphere because of vaporization. Figure 1
depicts the yield of product (ME) at 60°C was 80% at first 10 minutes of reaction time. At 30°C,
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the yield of ME was 75% compared to 78% product yield at reaction temperature of 45°C.
However, the maximum yield of product was achieved after 2 h of reaction time was 93.2%.
Ilgen (2012) also reported on the transesterification of canola oil using 3.0 wt % of catalyst
amount for 3 h of reaction time obtained the yield of product is about 91.78%.
From the equation (5), the rate of reaction may be determined accordingly, based on a decreasing
amount of reactant or an increasing amount of product. In this study, the increasing amount of
ME product was selected. Since the percent yield of product was as a function of time, the first
order rate of reaction can be derived as follows:
-r = dME/dt (6)
In this matter, dME is the % yield rate of product. The Equation (5) can be modified into the
following equation (6)
dME/dt = kME (7)
in order to derive furthermore the equation (7) to determine the reaction rate constant (k).
Assuming that the initial concentration of product at time = 0 is ME0, and the increasing
concentration of product at time = t is MEt.
∫∫ =t
t
MEt
MEdtkMEdME
00/ (8)
k = 2.303 (log MEt – log ME0) / t (9)
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Referring to Figure 2, after plotting the kinetics data on the first order graph was performed. The
curves showed a straight line for entire reaction temperatures. This trend proved that the
transesterification process matches to follow first order model. The determination of rate
constants for the reaction also depends on the reaction order.
Also, when reaction rate were plotted against temperatures, the graph produced a straight line
curve as shown in Figure 3. Thus, this trend indicated that there is a close correlation between
reaction rate constant with reaction temperature. Once reaction temperature was increased, the
reaction rate constant increased proportionally. The calculation of reaction rate constants which
is based on the increasing concentration of reactant was conducted and the results were as
tabulated in Table 1. Using the equation (9), the reaction rate constants under optimum
operational condition was computed as 1.19 x10-4 -1.30 x 10-4 min-1.
The Arrhenius activation energy was determined by plotting the entire reaction rate constants
against temperature in Kelvin (K) as indicated in Figure 4. The dependency of k on the reaction
temperature follows the Arrhenius law as:
( )RTEAk /exp −= (9)
Thus, Equation (10) was modified becoming the following equation.
−+=
RTEAk
303.2loglog 1010
(10)
where R is the universal gas constant and T is expressed in K.
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The Arrhenius activation energy (E) was estimated from the slope of a plot of log10 k versus 1/T.
The value of Arrhenius activation energy is provided in Table 2. The frequency factor (A) was
determined by the intercept. Berrios et al. (2010) reported the activation energy for biodiesel
production via esterification reaction was 6.86 kcal mol-1 (28.7 kJ mol-1). The required activation
energy for the transesterification reaction of waste cooking oil as Jain et al. (2011) reported was
about 21.21 kcal mol-1 (88.76 kJ mol-1).
The activation energy which attained in this study was the activation energy of first order
reaction which converted directly triglyceride into biodiesel (methyl esters). The obtained value
of activation energy was about 254.5 kcal mol-1, which is higher than other finding results. Thus,
the transesterification reaction of M. charantia oil into MSOMEs is relatively more difficult to
take place as reflected in its high activation energy compared to other oils. Particular values
mostly reported for the activation energies of alkali-catalyzed homogeneous and heterogeneous
transesterification reaction under three steps wises configuration were in the range of 10.52-
38.72 kcal mol-1 (Noureddini and Zhu, 1997; Liu et al., 2008; Vujicic et al., 2010).
Characterization of Momordica charantia Oil Methyl Esters (MSOMEs)
Fatty Acid Methyl Esters (FAMEs)
The fatty ester composition of MSOMEs as determined by GC is given in Table 3. The
MSOMEs contain 37.2% unsaturated fatty acids (UFA), whereas the level of saturated fatty acid
(SFA) was 64.11%. This result agrees well with profiles in the literature (Prashantha et al., 2009)
with stearic (approximately 35.08%), palmitic (approximately 3.09%), linoleic (approximately
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4.09%) and oleic acids (approximately 2.15%) being the most common fatty acids. Whereas, the
seed oil is also rich in α-eleosteric acid (50.04%) which also were quite agreed with our results
as depicted in Table 3.
The 1H-NMR and FT-IR spectra of MSOMEs were also determined and reported in term of data
in Table 4. The 1H-NMR spectrum agrees well with the spectra of vegetable oil methyl esters of
similar composition, further confirmed by a calculation of the fatty acid profile with a procedure
using peak integration values (Knothe and Kenar, 2004). The FT-IR spectra have been used to
identify functional groups and the bands corresponding to various stretching and bending
vibrations in MSOMEs as shown in Table 4.
Fuel Properties
The fuel properties of the Momordica charantia seed oil methyl esters (MSOMEs) were
determined and compared to the biodiesel American standard ASTM D6751 and European
standard EN 14214, as depicted in Table 5.
The cetane number (CN) is indicative of its combustion quality during compression ignition.
Higher cetane number value depicted the better ignition quality of the fuel. The cetane number
for MSOMEs has been found to be 64 (Table 5), which satisfied with quality standards that
prescribe a minimum of 47 (ASTM D6751), and minimum of 51 (EN 14214) limits (Table 5).
The CNs of the components of MSOMEs are methyl streate approximately 86.9, methyl oleate
approximately 55 and methyl palmitate with about 85 (Knothe et al., 2003), in order that the CN
of MSOMEs is well-explained in view of that each constituent contributes linearly to the overall
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CN. Therefore, the MSOMEs biodiesel agreed with the standards cab used as more ignitable fuel
than other conventional biodiesel fuels.
Kinematic viscosity (KV) represents the flow characteristics and the tendency of fluids to deform
by either shear stress or tensile stress. Because, KV is an important parameter of fuel atomization
and fuel distribution (Mittelbach, 1996). Hence, the kinematic viscosity at 40°C for MSOMEs
was determined to be 4.48 mm2s-1, which is within the ranges specified by the biodiesel
standards ASTM D6751 and EN 14214 (Table 5).
The oxidation of biodiesel fuel is an important factor, which helps in assessing the quality of
biodiesel. This oxidation stability is an indication of the degree of oxidation, potential reactivity
with air, and may determine the need for antioxidants. Table 5 shows that the induction period of
MSOMEs per the Rancimat oxidative stability test was (4.25 h) which meet the minimum
prescribed in the ASTM D6751-10 (3h) but did not satisfied the EN 14214-12 (8h) standard. The
reason for the higher oxidative stability time is the lower content of USFAs (37.2%), as
compared to SFAs (61.99%) especially methyl eleostericate (approximately 56.47%; see Table
1). This result can be attributed to the better oxidative stability of eleostearic acid comparison to
other comment fatty acids of the MSOMEs (Table 5). Therefore, MSOMEs stability can increase
to the minimum restriction prescribed in the EN 14214 standard by adding antioxidants i.e. tert-
butylhydro-quinone (TBHQ).
The vital factors which determine the cold flow properties of fuels are cloud point (CP), pour
point (PP) and cold filter plugging point (CFPP). In the present work the maximum values of CP
and PP of the MSOMEs were determined to be 9 °C and 15 °C (Table 5). ASTM standard
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D6751, no mention of a low-temperature parameter in its specifications; rather a “report” is
specified for cloud and pour point. However, each country can specify certain temperature limits
for different times of year depending on climate conditions (Knothe et al., 2006). The CFPP is
the temperature at which a fuel jams the filter due to the formation of agglomerates crystals.
CFPP test was conducted according to ASTM D 6371 which showed the CFPP value for
MSOMEs was 8 °C. This value is quite high because the MSOMEs composition has a high
percentage (62.7%) of saturated fatty acids (Table 5).
The temperature at which biodiesel will ignite, when exposed to a flame or spark is the fuel flash
point (FP), is higher than the petro-diesel standards of transportation safety. This parameter is
considered in storage, handling, and safety of fuels and other flammable materials. The FP in the
present investigations was 162°C (Table 5) and is higher than the minimum values prescribed in
ASTM D6751 and EN 14214.
Airless combustion systems also depend greatly on density and the standard for biodiesel
requires a higher density than 860-900 kgm-3 in EN 14214. The results achieved (889.4 kgm-3)
showed that the MSOMEs produced was within the specification limits (Table 5).
Other fuel properties of MSOMEs such as sulfur content, ash content, water content, copper strip
corrosion, free and total glycerol, methanol contents, monoglyceride, diglyceride and triglyceride
contents were also determined (Table 5). As expected, all other aforementioned properties of
MSOMEs/biodiesel conformed to EN 14214 and ASTM D6751 standards.
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CONCLUSION
Momordica charantia has relatively high oil content with low acid value, which facilitated direct
methanolysis for biodiesel production without any acid pretreatment. The fatty acid composition
of the M. charantia seed oil includes a high percentage of polysaturated fatty acids. The kinetics
study of MSOMEs has been successfully performed under various reaction temperatures and
other optimal reaction parameters. The reaction mechanism showed that the transesterification
taking place in a single straight forward reaction. The reaction rate constants follow the first
order reaction model. The obtained rate constant values are 1.19 × 10-4-1.30 × 10-4 min-1. The
activation energy is higher compared to other similar studies i.e. 254.5 kcal mol-1. It is due to the
reaction consumed a lot of internal energies to break down the intermediate hydrocarbon chains
to yield the final products. The most results of fuel properties, except oxidative stability,
compared well with EN 14214 and ASTM D6751. The oxidative stability of MSOMEs/biodiesel
was unsatisfactory in line with these standards. The oxidative stability would require the use of
antioxidants to meet specifications of EN 14214 and ASTM D6751 standards. It could be
concluded from the results of the present investigation that M. charantia oil as a non-edible oil
can be converted into biodiesel with very good yield and better quality of fuel properties.
ACKNOWLEDGEMENT
The data presented here is part of research thesis at Government College University Faisalabad
(GCUF). The authors are thankful to Dr. Nasir Rasool and Dr. Muhammad Zubair from
Chemistry Department, GCUF for their assistance.
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List of Tables
Table 1. Reaction rate constants at various temperatures
Table 2. Arrhenius activation energy
Table 3. Fatty ester profile of Momordica charantia oil methyl esters (MSOMEs)
Table 4. FTIR and NMR Data for Momordica charantia oil methyl esters (MSOMEs)
Table 5. Fuel properties of Momordica charantia oil methyl esters (MSOMEs)
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Table 1: Reaction rate constants at various temperatures
No. Temperature ( °C) Reaction rate constants (k) ( min-1) R2
1 30 0.00119 0.94
2 45 0.00124 0.95
3 60 0.00130 0.90
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Table 2: Arrhenius activation energy
Reaction Pathways Activation Energy R2
TG ME 254.5 kcal mol-1 0.99
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Table 3: Fatty ester profile of Momordica charantia oil methyl esters (MSOMEs)
FAMEs MSOMEs (%)
Palmitic acid (C16:0) 3.09 ± 0.21
Stearic acid (C18:0) 34.11 ± 2.31
Oleic acid (C18:1) 2.15 ± 0.50
Linoleic acid (C18:2) 4.09 ± 0.67
α-Eleosteric acid (ctt, 9,11,13–18:3) 51.56 ± 5.18
β-Eleosteric acid (ttt, 9,11,13–18:3) 4.91 ± 2.69
Values are mean ± SD of triplicate determinations
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Table 4: FTIR and NMR data for Momordica charantia oil methyl esters (MSOMEs)
Ester FTIR (cm-1) 1H NMR (400 MHz, CDCl3)
MSOMEs 3009, 2922, 2853, 1741,
1460, 1168, 992, 723
δ 5.33 (m, 2H), 3.63 (s, 3H),
2.28 (t, 2H), 2.03 (m, 2H),
1.25 (m, 28 H), 0.89 (t, 3H)
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Table 5: Fuel properties of Momordica charantia oil methyl esters (MSOMEs)
Property MSOMEs ASTM D6751 EN 14214
Cetane number 64.0 ± 4.80 47 min 51 min
Kinematic viscosity (mm2/s; 40 °C) 4.48 ± 1.02 1.9-6.0 3.5-5.0
Oxidative stability (h) 1.99 ± 0.85 3 min 8 min
Cloud point (°C) 9.00 ± 2.12 Report -a)
Pour point (°C) 15.00 ± 1.82 -b) -a)
Cold filter plugging point (°C) 8.00 ± 2.00 -b) -a)
Flash point (°C) 162 ± 11.20 93 min 120 min
Sulfur content (%) 0.012 ± 0.003 0.05 max -
Ash content (%) 0.016 ± 0.12 0.02 max 0.02 max
Acid value (mg KOH/g) 0.40 ± 0.39 0.50 max 0.50 max
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Values are mean ± SD of triplicate determinations
a) Not specified. EN 14214 uses time and location-dependent values for the cold filter
plugging point (CFPP) instead.
b) Not specified.
Copper strip corrosion (50 °C, 3 h) 1a No. 3 max No. 1 min
Density (15°C), kg.m-3 889 ± 10.50 - -
Monoglyceride content, % 0.71 ± 0.003 - 0.80 max
Diglyceride content, % 0.15 ± 0.002 - 0.20 max
Triglyceride content, % 0.13 ± 0.001 - 0.20 max
Methanol content, % 0.18 ± 0.002 - 0.20 max
Free glycerol 0.014 ± 0.001 0.020 max 0.020 max
Total glycerol 0.170 ± 0.03 0.240 max 0.250 max
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List of figures
Figure 1. Methyl esters (ME) yield versus time for alkali catalyzed transesterification
Figure 2. Plot of first order model
Figure 3. Plot of reaction rate constant versus temperature
Figure 4. Plot of reaction rate constants (k) versus temperature (K)
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Figure 1: Methyl esters (ME) yield versus time for alkali catalyzed transesterification
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Figure 2: Plot of first order model
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Figure 3: Plot of reaction rate constant versus temperature
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Figure 4: Plot of reaction rate constants (k) versus temperature (K)
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