Heterogeneous Transesterification of Luffa aegyptiaca Oil to Biodiesel

Heterogeneous Transesterification of Luffa aegyptiaca Oil to Biodiesel
Heterogeneous Transesterification of Luffa aegyptiaca
Oil to Biodiesel
*Oche S. Gabriel1,5, Adamu T. Jummai2, David I. Dahutu3 and Gambo H. Peace4
1,2,3,4
Bioresources Development Centre, National Biotechnology Development Agency, Federal Ministry of Science and
Technology, Jalingo, Taraba state, Nigeria.
5
Department of Chemistry, School of Pure and Applied Science, Modibbo Adama University of Technology, Yola, Nigeria
In the continuous desire to find suitable alternative, renewable and biodegradable source of oil
for commercial diesel Luffa aegyptiaca oil was converted into biodiesel through
transesterification reaction using heterogeneous hydrotalcite particles from MgO/Al2O3/Kaolin
clay as catalyst and methanol as solvent at controlled reaction conditions. The characterization
results of pure Luffa aegyptiaca oil and biodiesel samples was obtained and compared: moisture
content 0.0045 %-0.0034 %, ash content 0.00 %-0.02 %, saponification value 194.5 - 61.43, acid
value 9.65-0.144, freezing point 5.00 - 30.00 min, pour point 5.00-3.00 min, density 0.969 g/mL-
0.889 g/mL, while the flash point gave 349 k-345 k, specific gravity 0.865 g/mL-0.851 g/mL, and
viscosity 34.95 Nsm-2
- 5.82 Nsm-2
accordingly. The catalyst sample (MgO/Al2O3/Kaolin clay) after
characterized using X-Ray Diffractometer, showed promising surface activity and selectivity on
both the calcined and uncalcined catalyst. The optimum transesterification reaction conditions
was obtained at 333 k, 6 hours reaction time and 6% catalyst concentration. The reaction
conditions had direct effect on percentage yield of the biodiesel product with maximum yield of
79.61 % obtained for untreated oil but 81.27 % for treated oil at 333 k, 3 hours reaction time and 2
% catalyst concentration. FT-IR spectra analysis of biodiesel oil revealed decrease in frequency
band of the hydroxyl group (O-H) between 1780 cm-1
and 1700 cm-1
and its subsequent absence
at 1730 cm-1
. The Gas Chromatography-Mass Spectrophotometer composition for pure Luffa
aegyptiaca oil and Biodiesel oil showed that free fatty acid was converted to fatty acid methyl
esters. Thus, transesterification of Luffa aegyptiaca oil sample using MgO/Al2O3/Kaolin clay
heterogeneous catalyst was a success.
Keywords: Biodiesel, Luffa aegyptiaca, transesterification, heterogeneous catalyst, kaolin clay/Al2O3/MgO, Calcined
INTRODUCTION
A great number of plants part from jatropha, cotton, luffa,
soya, etc, are all of domestic and medicinal importance,
hence they are called economic plants. Seeds are
fertilized ovules with embryo and can germinate into new
plants, seeds contain the greatest concentration of protein,
fats and oils present in plants (Njerum, 1997).
The evaluation of raw material requirement in Nigeria
indicates that past effect have been concentrated on the
exploration and exploitation of petroleum to some extent,
metallic mineral resources. Today the uses and diversity
in the application of catalyst or crystal structures in the
research and processing of plant derived products have
assumed significant dimensions. The local sourcing of raw
materials in order to conserve foreign exchange,
promotion of industrial development and thrust for national
self-reliance are some of the driving forces of our
economic policy. In the development, exploitation and
utilization of raw materials, only natural renewable and
degradable ones should be encouraged, because of the
global constant demand for energy and alternative raw
materials for fossils as well as for wide variety of industrial
product (Clasen and Kulicke, 2001).
*Corresponding Author: Oche S. Gabriel, Bioresources
Development Centre, National Biotechnology
Development Agency, Federal Ministry of Science and
Technology, Jalingo, Taraba State, Nigeria. E-mail:
ochesundaygabriel80@gmail.com
Co-Author 2
Email: jummaiadamu76@yahoo.com
3
Email: didahutu@yahoo.com
4
Email: gambopeace9@gmail.com
Research Article
Vol. 6(1), pp. 080-091, May, 2020. © www.premierpublishers.org, ISSN: 0524-0557
International Research Journal of Biochemistry and Biotechnology

Oche et al. 081
Fats and oil are carboxylic esters (trimesters) derived from
glycerol and are known as glycosides or triglycerides. In
chemical technology, transesterification process is now
used to convert seed oils as raw materials to biofuels via
catalytic means. In homogenously catalyzed
transesterification process, whether an acid or base
catalyzed, suffers some drawbacks in terms of process
integrity (Dae-Won et al., 2009): The corrosion of the
reactor and pipelines by dissolved acid/base species,
impossibility of catalyst recovery from the reactant-product
mixture resulting to environmental pollution when
disposed, lastly is the limitation in establishing a
continuous process.
Thus, heterogeneously catalyzed process, especially
those involving solid base catalysts, has been suggested
and studied continuously by academia and industry
(Ogunkunle et al., 2017).
This work is aimed at investigating the heterogeneous
transesterification of Luffa aegyptiaca oil to biodiesel using
kaolin clay/Al2O3/ MgO solid base catalyst and possibly
explain an expected high yield of biofuel from the catalytic
transesterification process adopted in this research work.
The specific objectives of the research are to:
(i) Evaluate the particle size and the crystalline nature of
solid catalyst mixture.
(ii) Extract Luffa aegyptiaca oil from the seeds of Luffa
aegyptiaca plant.
(iii) Produce biodiesel from Luffa aegyptiaca oil using
kaolin clay/Al2O3/MgO as solid catalyst.
(iv) Study the physicochemical characteristics, functional
groups and fatty acid composition of Luffa aegyptiaca
oil and biodiesel.
(v) Explain the efficiency of the heterogeneous
transesterification process based on the effect of
molar ratio of methanol to oil, water content, reaction
time, temperature and mass of catalyst to oil ratio.
At present, instead of the use of catalyst in petroleum and
some metallic resources, more interest has been focused
in the use of catalyst from natural raw materials to catalyze
seed oil for production and use as biodiesel that are more
environmentally friendly, acceptable and biodegradable. If
possible, explain the effect of molar ratio of methanol to oil,
water content, reaction time and mass ratio of catalyst to
oil stating what can be done to ascertain the acceptability
of the empirical relationship.
MATERIALS AND METHOD
Apparatus/instruments
The apparatus used are within Abti American University
(AAU), Yola, Nigeria; Round bottom flask, condenser,
hotplate, thermometer (373 k), conical flask (250 ml, 500
ml, and 1000 ml), beaker (100 ml, 250 ml, 500 ml and 1000
ml), separating funnels (250 ml and 500 ml), test tubes,
desiccator, burette, pipette, retort stand, electronic
weighting balance, filter paper, soxhlet, distiller, sampling
bottles and tubes, spatula, magnetic stirrer, corks, funnels,
stop watch, hand gloves, nose mask, mortar and piston
(ceramic and metal), sieve (100 µm), foil paper, indicator
(phenolphthalein), petri dish, crucibles, clamps, oil bath,
water bath, steam bath, pH meter, muffle furnace, oven
(523 k, 1273 k), refrigerator, Gas Chromatography and
Mass Spectrophotometer, Fourier Transform Infrared, X-
ray diffractometer, viscometer, centrifuge (8,000 rpm).
Reagents
Methanol, hexane, sulphuric acid (H2SO4), sodium
hydroxide (NaOH), potassium hydroxide (KOH), kaolin
clay (Al2S2O4(OH)4), hydrated Al2O3, hydrated MgO and
sodium trioxocarbonate (Na2CO3), distilled water and urea
were obtained from the department of chemistry, School of
Pure and Applied Science, Modibbo Adama University of
Technology, Yola, Nigeria, while Luffa aegyptiaca oil was
extracted using sohxlet distiller from Luffa aegyptiaca seed
gathered from surrounding of the institution and diesel oil
from Nigerian National Petroleum Cooperation depot, Yola
Depot.
METHODS
Experimental procedure
This investigation was carried out in Abti American
University (AAU), Petroleum Technology laboratory, using
non-edible vegetable oil from Luffa aegyptiaca plant for
production of biodiesel as illustrated by Hirata et al.,
(2007). The uniqueness of this investigation is the
heterogeneous system created to investigate the
production of biodiesel. It involves the use of
heterogeneous base catalyst Clay/Al2O3/MgO.
Determination of fatty acid composition in the oil
Calculation of molecular weight of Luffa aegyptiaca.
𝑀 =
56.1 × 1000 × 3
𝑆𝑉−𝐴𝑉
Equation (1)
Where AV is the acid value (mg KOH/g oil) and SV is the
saponification value (mg KOH/g oil) as shown by Hawash
et al., (2011).
Experimental setup
The experimental set-up consisted mainly of round glass
reactor placed in an adjusted temperature water bath. The
flask was provided with reflux condenser, magnetic stirrer,
thermometer for temperature follow up and funnel for
methanol addition, the reaction was carried out at a
temperature of 333 k.

Int. Res. J. Biochem. Biotechnol. 082
Catalyst preparation
Hydrotalcite particles with Mg/Al molar ratio of 3/1 was
synthesized by coprecipitation method using Kaolin clay/
NaOH as precipitating agents. In this method a solution
containing 0.28 mol of Mg (NO3)2.6H2O and 0.09 mol of Al
(NO3)3.9H2O mixed with 0.84 mol of NaOH and 0.25 mol
of Kaolin clay was prepared at room temperature under
vigorous stirring for 12 hours at 353 k, after which the
resulting sample was filtered and washed with deionized
water until pH was obtained. The hydrotalcite was dried at
333 k for 12 hours, after which the dried solid
(Clay/Al2O3/MgO) particles was milled and sieved (100
mesh), then calcined at 773 – 823 k for 6 – 9 hours in a
muffled flask. After cooling in a desiccator at room
temperature the base Clay/Al2O3/MgO catalyst was used
for transesterification (Xie et al., 2006; Liu et al., 2007;
Deng et al., 2011).
Transesterification reaction
The production of biodiesel was carried out according to
the internationally acceptable standard (Hirata et al.,
2007). Refluxing of methanol in the heterogeneous
reaction system was employed according to (Hawash et
al., 2011) to transesterify the vegetable oil to biodiesel.
In the reaction, the catalyst was weighted out using
electronic weighing balance, poured into the methanol and
dispersed with mechanical stirring (about 600rpm). Then
the above pretreated oil was added into the mixture and
heated to 333 k by water bath for 6-9 hours. After reaction,
excessive methanol was distilled off under a vacuum
condition (evaporation) and the two phases (glycerol and
biodiesel) were separated out using a separating funnel
and the catalyst was recovered by filtration using filter
paper.
Catalyst dosage variation
The amount (%wt) of the catalyst from the range of 1% -
9% for the base Clay/Al2O3/MgO catalyst was varied and
the corresponding yield of methyl ester at a temperature of
333 k for 9 hours with methanol to oil ratio of 3:1 and 600
rpm was observed.
Variation of molar ratio of methanol to oil
The next investigation was the variation of molar ratio of
methanol to oil, the rate of ratio chosen was from 3:1 –
12:1, using the base Clay/Al2O3/MgO catalyst
consecutively under these reaction conditions; 333 k,
atmospheric pressure, 9 hours under a catalyst dosage of
1-9% w/v and 600 rpm.
Variation of reaction time on methyl ester yield
Another very important investigation under this work is the
variation of reaction time to observe the % yield of the
biodiesel using the base Clay/Al2O3/MgO catalyst. The
observation was carried out from 0hrs – 9hours using a
methanol to oil ratio of 3:1 and temperature of 333 k with
catalyst concentration of 1-9 % w/v and 600rpm.
Physicochemical properties of biodiesel
The biodiesel properties such as viscosity, flash point and
specific gravity were carried out using ASTM standard
methods. Unlike the use of vegetable oils in the food
industries. The petroleum industry has its own testing
protocol for product evaluation (Liston, 1993). The
following test was carried out to evaluate the performance
and effectiveness of the seed oils as biodiesel prior to
modification.
Viscosity measurement
Viscosity is the property of a fluid that causes it to resist
flow which mechanically is the ratio of shear stress to
shear rate. Viscosity may be visualized as a result of
physical interaction of molecules when subjected to flow.
This was determined by the Cannon-Fenske viscometer
and a circulatory bath with temperature control. Viscosity
was calculated using ASTM method D445-97 (ASTM,
1997).
The viscometer was washed and dried. The sample was
sucked into it and then immersed into the circulatory bath
set at 303 k. The time of flow of sample from upper mark
to lower mark of the viscometer was recorded using a stop
watch. The experiment was repeated thrice and average
flow time recorded. This was carried out on oil before and
after transesterification.
The instrumental constant was obtained from the
viscometer thus viscosity of the sample was calculated
using the formula below:
Viscosity (V) = K T, Equation (2)
Where K = Instrumental constant
D =Density of the sample
T = Efflux time (sec)
Specific gravity determination
For many liquids, specific gravity is used as the ratio of the
mass of a given volume to the mass of an equal volume of
water. Therefore, specific gravity is dimensionless.
Specific gravity decreases with increasing temperature
and decreases as viscosity decreases. Specific gravity
was determined according to the standard method
contained in ASTM D5002 (ASTM, 1998). The sample oil
was poured into a vertical glass cylinder and a hydrometer
was placed in the oil and allowed to be stable. The value
of the specific gravity was taken from the marking on the
stem of the hydrometer at the surface of the oil.

Oche et al. 083
Flash point determination
Flash point is an indication of the combustibility of the
vapour of oil, and it is defined as the lowest temperature at
which the vapour of the oil can be ignited under specific
conditions. Flash point is clearly related to safety.
Determination of flash point for the oil samples was done
using the ASTM D-92 method. An open cup containing the
oil sample was heated at a specific rate while periodically
passing a flame over its surface. The lowest temperature
at which the oil vapour ignites but could not sustain a flame
was recorded as the flash point.
Other physicochemical properties were carried out as
follows: saponification number and free fatty acid.
Saponification number
This parameter was determined by the standard method of
AOAC (2000). This is the number of milligram of KOH
required to react completely to saponify 2 g of oil. 1g of oil
sample was accurately weighted into a clean round bottom
flask, after which 25 ml of 0.5 M alcoholic KOH was added
to it. The flask was then fitted on a condenser and the
solution refluxed for 30min. The solution was titrated while
still hot against 1M H2SO4 and the test value recorded.
Similar procedure was followed and the blank obtained
respectively. The difference between the blank and the
test titer values gives the amount of KOH absorbed by the
oil.
Saponification value =
28.05 (V1 − V2)
Weight of oil sample
Equation (3)
Where V1= blank titer, and V2 = test titer.
Determination of free fatty acid
The acid value is the number of milligram of KOH required
to neutralize the acid (free organic acid) in 1 g of sample.
It is a measure of the free fatty acids present in the sample
in a conical flask. The mixture was heated on a hot plate
until it boiled, after which it was then removed and titrated
against 0.1 M KOH to the end point with two drops of
phenolthalein until a permanent pink colour persisted.
Free Fatty Acid (FFA) =
28.2 × normality × titre value
Sample weight
Equation (4)
X-ray diffraction analysis
The method outlined by Ponarulselvam et al. (2001) will be
adopted. The particle size and nature of catalyst will be
determined using XRD. This will be carried out using
shimadzu XRD-6000/6100 model with 30 kv, 30 mA with
Cu Kα radians at 2θ angle. X-ray powder diffraction is a
rapid analytical technique primarily used for phase
identification of crystalline material and can provide
information on unit cell dimensions. The material to be
analyzed will be ground, and an average bulk composition
will also be determined.
Fourier transform infrared spectrometer
The FTIR analysis will be done over the spectral range of
4000-400 cm-1. The properties of the oil will be
characterized by Shimatzu 8400S Fourier Transform
Infrared Spectrometer (Barbara, 2004).
Gas chromatography-mass spectrometry
The GC-MS analysis will be performed on the Hewlett
Packard 5972 mass spectrometer operated at ionization
energy of 70eV linked to an HP-5890 gas chromatography,
with a splitless injector (at 523 k), fitted with a flexible silica
capillary column of 30 m × 0.32 mm internal
diameter, 1.0 µm film thickness. About 1µL of each sample
will be injected by an auto sampler, the oven temperature
will be programmed from 40 to 3773 k at a rate of 313 k/min
and held at 3273 k for 20 min, using helium, career gas at
a flow rate of 1 ml/min, the samples were run using full
scan, single ion monitoring (SIM) and recorded using HP
chemstation system (Odebunmi and Ismaeel, 2012).
RESULTS AND DISCUSSION
Characterization of Pure Luffa aegyptiaca Oil and
Biodiesel
The results of the properties as indicated in Table 1, for
PLO and BD1 showed that during the transesterification
process, the ash content which is a reflection of the
inorganic composition was determined (0.02) and falls
within the range required as indicated in the standard
(0.05). Transesterification also changed the pH value from
6.47 to 7.47 which were significant as compared to the
standard value of ≥ (less than) 7.15. After the
transesterification of the PLO to BD1 the pour point and
freezing point reduced and increased with time as shown
respectively; 12 min (PLO) – 5 min(BD1) and 5 min(PLO)
– 30 min(BD1). The determined values of density, specific
gravity, flash point, moisture content and viscosity gave
reductions from 0.969 g/mL to 0.889 g/mL, 0.865 g/mL to
0.851 g/mL, 349 k to 345 k, 0.0045 % to 0.0034 %, 34.95
Nsm-2 to 5.82 Nsm-2 respectively. This shows the effective
catalyst prepared from the use of kaolin clay incorporated
with MgO and Al2O3 as catalyst. The density and specific
gravity are indications of efficient flow on application of the
biodiesel in combustion engines, given the proof that the
biodiesel will combust in an engine with minimum
environmental effect (Hawash et al., 2011).
Characterization of Kaolin Hydrotalcite
Heterogeneous Base Catalyst
XRD patterns of hydrotalcite particles with Mg/Al molar
ratio of 3:1 as given in Figure 1 shows that particles

exhibited a single phase, corresponding to a typical
hydrotalcite structure with strong, sharp, and symmetric
peak for the (12),(24),(26),(25),(38),(50), and (62) planes
as well as broad and symmetric peaks for
the(45),(54),(56),(58),(59),(63),(71) and (73) planes. The
average particle size was calculated as 5.1 nm by Scherer
equation:
Dc = k ((α/β). Cos θ) Scherer equation. Equation (5)
Where
Dc = is the average particle size = 5.1 nm
K = is the Scherer constant = 0.89
α = is the X – ray wavelength, (CuKα) = 0.1541 nm
β = is the full width at half maximum (FWHM) = 0.026261
nm
θ = is the diffraction angle = 13.31200
After calcination at 773 k for 6 hours, hydrotalcite complex
was decomposed into mixed Mg – Al oxides, which were
confirmed by XRD pattern as shown in Figure 2. For the
calcined particles, the characteristic reflections were
observed clearly at 2θ of 26.6240, 50.7780 and 68.3020,
corresponding to SiO2 and MgO-like phase or magnesia-
alumina solid phase. The peaks of SiO2 and Al2O3 phase
were very small, indicating that Al3+ cations were dispersed
in the structure of MgO without the formation of spinel
species (Hargreaves, 2016).
Transesterification of Luffa aegyptiaca Oil using
Kaolin Hydrotalcite
Heterogeneous Base Catalyst
Transesterification of triglyceride as shown in Figure 3, is
used to reduce the viscosity and produces fatty acid alkyl
esters and glycerol. The process or reaction gives a three
layer mixture after a high speed centrifugation at 8,000 rpm
for 15 min, with the catalyst at the bottom, then the glycerol
layer at the middle and biodiesel at the top in the reaction
vessel. Excess methanol (100%) was used to force the
reaction in the forward direction producing corresponding
methyl esters and glycerol, thus, referring to the process
as methanolysis (Deng et al., 2011; Schuchardt et al.,
1998).
ROH + B RO- + BH+
The chemistry of transesterification which is an equilibrium
reaction that occur by mixing the reactants in the presence
of a catalyst specifically the base catalyzed process
(Schuchardt et al., 1998) is:
Equation (6): the reaction of the base with alcohol,
producing an alkoxide and the protonated catalyst,
Equation (7): nucleophilic attack of the alkoxide at the
carbonyl group of the triglyceride generates a tetrahedral
intermediate,
Equation (8): the formation of alkyl ester and the
corresponding anion of the diglyceride,
Equation (9): The latter deprotonate the catalyst, thus
regenerating the active species, which is now able to react
with the second molecule of the alcohol, starting another
catalytic cycle. Diglycerides and monoglycerides are
converted by the same mechanism to a mixture of alkyl
esters and glycerol (Schuchardt et al., 1998).
Effect of Preparation Condition on Luffa aegyptiaca
Oil Conversion to Biodiesel
Effect of catalyst dosage
The calcined nanoparticles as catalyst showed high
activity because they possessed strong basic sites and
large surface area. The effect of catalyst dosage on the
conversion of Luffa aegyptiaca oil to biodiesel was
investigated. The catalyst was measured at different
percentage (w/v %) and mixed properly before refluxing at
333 k for 3 hours under 3:1 molar ratio of methanol/oil.
That catalyst dosage of 6% (w/v %) showed the highest
conversion of 79.61% (for untreated oil). The reason for
the increase in biodiesel yield from 35.26% min - 79.61%
max was due to the increase of catalyst from 1% - 6% (w/v
%), which increased contact between reactants and wider
surface area with more catalyst active centers as
represented in Figure 4. But 81.27% biodiesel yield was
obtained when the oil was treated. As the dosage of
catalyst increased, more products where absorbed and the
yield of biodiesel decreased, which is in view with previous
research and findings (Hawash et al., 2011).

Oche et al. 085
At 9% (w/v) of kaolin hydrotalcites the biodiesel yield
decreased, which was possible due to a mixing problem
involving reactants, products and solid catalyst.
Furthermore, when excessive catalyst was used, the
transesterification process was easily emulsified and
resulted in difficulties during separation of products (Deng
et al., 2011).
Effect of molar ratio of methanol to oil
Theoretically raising the molar ratio of methanol to Luffa
aegyptiaca oil favors the reaction (Hawash et al., 2011) i.e.
stoichiometrically, 3 mole of methanol were required for
each mole of Luffa aegyptiaca oil. However, practically
methanol/oil molar ratio should be higher than that of
stoichiometry in order to drive the reaction towards
completion and production of more methyl esters.
Moreover, Figure 5 showed that methanol can increase
the dissolution of Luffa aegyptiaca oil, intermediates and
biodiesel resulting in the wastage of the materials. When
the ratio increased from ratio 6/1 to 9/1, the yield of methyl
ester increases gradually from 63.41% to 69.44%. But it
was observed that at molar ratio above 9/1, excessive
methanol had no significant effect on the yield (Deng et al.,
2011).
Effect of reaction time
Because it was a heterogeneous reaction, the mass
transfer tends to be slow at 1 hour with biodiesel yield of
42.17%, but at 3 hours the biodiesel yield increased
drastically to 62.07% which further increased to 73.68% at
6 hours reaction time. Finally, an increase in biodiesel yield
was observed at 9 hours reaction time with 73.97%
biodiesel production. These phenomena showed in Figure
6 agreed with previous research findings which stated that
longer time was required for the subsequent separation
stage because the separation of the esters layer from
glycerol was difficult due to the fact that methanol with one
polar hydroxyl group could emulsify product (Deng et al.,
2011).
Effect of reaction temperature
Reaction temperature was also an important factor that
influences the biodiesel yield in this research. Each
experiment was run for 3 hours with 3% (w/v) catalyst and
3/1 molar ratio of methanol/oil content. The result indicated
in figure 7 showed that biodiesel yield was low at a low
temperature with only 34.79% yield at 313 K for 6 hours
which increased at constant time of 6 hours to 58.35%
yield at 318 k and then to 60.26% yield at 323 k, 67.15%
was obtained at 328 k with a highest of 73.68% yield
obtained at a temperature of 333 k, slight decrease of
59.10% yield at 338 k was then observed (Deng et al.,
2011).
Comparation of kaolin clay/MgO/Al2O3 with different
catalyst models such as;
Na2CO3/Al2O3/MgO, Urea/Al2O3/MgO and KOH on
treated oil.
The activity of the catalyst prepared was compared with
different catalyst models keeping the temperature, catalyst
dosage, time and methanol/oil ratio constant. Figure 8
showed values obtained were 81.26 %, 93.64 %, 91.72 %
and 87.51 % for Kaolin, Na2CO3, Urea and KOH
respectively (Hawash et al., 2011).
Effect of temperature on the viscosity of PLO, BD1 and
CD
The effect of temperature on the viscous flow of PLO,
BD1and CD as represented in Figure 9, was determined
in order to obtain a suitable temperature of the biodiesel
(BD1) compared to the commercial diesel (CD) was
represented in Figure 10.
Fourier Transform Infra-Red Analysis
A more suitable blend ratio of biodiesel/commercial diesel
was obtained at 303 k and 313 k with viscosity of 5.25
Nsm-2 and 4.23 Nsm-2 respectively and blend ratio of
20:80. Table 2 showed that the PLO peaks were seen to
have bands at 585, 722, 1163, 1375, 1461, 1655, 1745,
2679, 2853, 2923, 3005 and 3473 cm-1. While those of the
BD1 were seen at 512, 722, 1170, 1362, 1462, 1655,
1743, 2363, 2854, 2925, 3005 and 3461 cm-1 along with
their expected functional groups. These spectral bands are
displayed in Figures 11, 12 and 13 respectively which are
discussed according to the regions obtained in the FTIR
spectra. This data suggests that, the biodiesel samples
indicated proof of successful transesterification.
The region (3700–3200) cm-1
This region is characterized by hydroxyl (O-H) group of
alcohol and phenol, amine (N-H) and methyl (C-H)
stretching bonds. The appearance of the frequency band
3473 cm-1 PLO sample spectra is an indication of the O-H
stretching vibrations. However, the decreased stretching
frequency at 3473–3461 cm-1 in the hydroxyl of the
biodiesel samples spectra showed proof of biodiesel
synthesis. Thus, justified with increase in the absorption
1655 cm-1 is an indication of the C=C stretching band of
alkenes (Pavia et al., 2001).
This region is characterized by the presence of O-H
carboxylic acid, vinyl C-H, aryl C-H, sp3 alkyl (C-H) and C-
H aldehyde. The frequency band 2923 cm-1 in PLO sample
spectra depict the C-H stretch associated with oil. The
spectra of biodiesel sample also showed the presence of
C=C stretching bands of the biodiesel samples with 2925
cm-1 (Pavia et al., 2001).

This region comprises of alkynes C≡C, nitriles C≡N and
carboxylic acid O-H absorption band. The PLO sample
spectra in Figure 11 revealed the absorption band at 2679
cm-1, while the biodiesel samples showed its reduction to
2363 cm-1 (Pavia et al., 2001) .
The region (1850 – 1100) cm-1
This region is mainly dominated by the carbonyl group
(C=O) of esters, ketones, aldehyde, carboxylic acids and
amides. The study of hemicelluloses and lignin reveal that
absorption lines situated between 1510 and 1600 cm-1 is
caused by lignin while the absorption band at 1730 cm-1 is
caused by hemicelluloses, thus, the C=O stretch in
conjugated ketones, esters and carbonyls groups are
proved.
Interestingly, the biodiesel samples spectra have shown
evidence of transesterification with increased absorption,
high yield and enhancement of 1645 cm-1, 1730–1650 cm-
1 C=O stretching, 1350–1400 cm-1 which is C–H bond in –
O(C=O)–CH3 group. All esters give rise to three strong
infrared bands that appear at approximately 1700 cm-1,
1300 cm-1 and 1200 cm-1, known as the rule of three
(Bodirlau and Teaca, 2009). .
This region is also referred to as the finger print region,
having a lot of complex derivative of the alkyl (cyclobutane,
cyclopentane); the aryl derivatives, alkene residues (S–
CH=CH2). Aliphatic, substituted aromatic group, stretching
frequencies of S–CH3=Si–Cl2–Si–O, boron compounds,
halogens, substituted aromatic groups at 900–415 cm-1,
double bond nitrates (O–N=O) at 690–615 cm-1,
conjugated cyclic system at 960–930 cm-1, isocyanates at
675–605 cm-1, aliphatic at 580–555 cm-1,aromatic at 580–
430 cm-1, aryl (R1–C=C–R2) at 540 – 465 cm-1,
monosubstituted aryl 695 – 575 cm-1, alkane residues (R–
CH–CH2) at 995–445 cm-1, S–CH=CH2 at 965 – 860 cm-1,
-C≡CH bending at 700 – 600 cm-1 (Dean, 1999).
Gas Chromatography and Mass Spectrographic
(GCMS) Analysis
Table 3 indicates the GCMS spectrum of PLO (Pure Luffa
aegyptiaca Oil) with composition of oleic acid (18:1)
27.12%, linoleic acid (18:2) 46.32%, palmitic acid (16:0)
20.90%, stearic acid (18:0) 5.94% and arachidonic acid
(20:0) 1.23% was converted successfully into diglyceride
and monoglyceride, and finally into glycerin and Fatty Acid
Methyl Esters (FAME) as shown in Figure 14 and 15,
where in BD1 (Biodiesel oil) showed that the
transesterification process consist of three consecutive
reversible reactions. Table 3 shows that the biodiesel
produced consisted of four most abundant FAMES
namely; oleic acid (18:1) 22.37%, linoleic acid (18:2)
50.19%, palmitic acid (16:0) 11.20%, stearic acid (18:0)
7.70% and arachidonic acid (18:1) 2.40% methylesters
was obtained (Xie et al., 2006; Barakos et al., 2008).
CONCLUSION
In the current investigation, it was confirmed that Luffa
aegyptiaca oil can be used as resources to obtain
biodiesel. The experimental results showed that
heterogeneous catalyzed transesterification reaction is a
promising area of research for the production of biodiesel
in a large scale. Effect of different parameters such as
temperature, time, reactant ratio and catalyst
concentration on the biodiesel yield was analyzed. The
best combination of the parameter was found at 6:1 molar
ratio of methanol to oil, 6 % kaolin clay/ MgO/Al2O3 base
catalyst, 333 k reaction temperature and 6 hours of
reaction time. The optimum condition yielded
approximately 80% of biodiesel. From the characterization
of the biodiesel, the physical properties of the biodiesel
from Luffa aegyptiaca oil with methanol were found to be
within the ASTM specified limit. Also, the characterization
of the kaolin clay/ MgO/Al2O3 base catalyst showed good
catalyst activity after calcination at 773 k. The viscosity and
density of Luffa aegyptiaca oil reduced substantially after
transesterification and it’s comparable to petrol diesel.
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Accepted 4 May 2020
Citation: Oche SG, Adamu TJ, Dahutu ID, Gambo HP
(2020). Heterogeneous Transesterification of Luffa
aegyptiaca Oil to Biodiesel. International Research Journal
of Biochemistry and Biotechnology, 6(1): 080-091.
Copyright: © 2020 Oche et al. This is an open-access
article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.

APPENDIX
Table 1: Physico-chemical properties of PLO and BD1
Parameter PLO BD1 Standard
Ash content (%) - 0.02 ≤ 0.05
Freezing point (min) 5.00 30.00 56.00
Pour point (min) 5.00-12.00 3.00-5.00 3.00-5.00
Specific gravity (g/mL) 0.865 0.851 0.850-0.900
Density (g/mL, 303 k) 0.969 0.889 0.875-0.900
Flash point (k) 349 345 ≥ 373
Viscosity (Nm-2/sec, 313 k) 34.95 5.82 3.5-5.0
Colour greenish brown Bluff NA
Acid value 9.65 0.144 ≤10.0
Saponification value 194.95 61.33 ≤ 197
pH value 6.47 7.47 ≥ 7.15
Moisture content (%) 0.0045 0.0034 -
NA- Not available
PLO – pure Luffa aegyptiaca oil, BD1- biodiesel from Luffa aegyptiaca oil and German standard.
Fourier Transform Infrared (FTIR) Spectrophotometric Analysis
Table 2: Characterization of PLO, BD1 and CD with their respective Bands and Functionality
Wave number (cm-1)
Peak PLO BD1 CD Functional Group Assessment
1 3473.99 3461.60 3434.13 (s, b) OH (stretch, H-bond) Alcohol, Phenols.
2 3005.69 3005.19 - (s) (m) –C–H, =C–H (all Stretch), alkenes and aromatics.
3 2923.77 2925.55 2982.71 (m) –C–H (stretch) alkanes.
4 2853.79 2854.62 2855.13 (m) –C–H (stretch) alkanes.
5 2679.52 2363.39 2365.10 (s, vb) -COOH Carboxylic Acid.
6 1745.48 1743.38 - (s) -C=O (stretch) esters, carboxylic acid and saturated aliphatic.
7 1655.29 1645.39 1635.89 Variable C=C (stretch).
8 1461.98 1462.23 1460.25 (m) -C–H (bend) alkanes.
9 1375.58 1362.42 1364.05 (m) -C–H (rock) alkanes.
10 1163.73 1170.96 - (m) -C–H wag (-CH2x) alkyl halides.
11 722.64 722.92 722.71 (m) -C–H (rock) alkanes.
12 585.30 512.36 510.95 (s) -C–Cl (stretch) alkyl halides
Pure Luffa aegyptiaca oil (PLO).
Luffa aegyptiaca biodiesel (BD1) using Kaolin catalyst.
Commercial diesel (CD).
Table 3: GC–MS Characterization of Luffa aegyptiaca Biodiesel.
S/No Free fatty acid Systematic name Quantity (%)
1 (9Z)–Octadecenoic acid, methyl ester
C18H34O2
Oleic acid
18:1
22.37
2 9, 12–Octadecenoic acid, methyl ester
C19H34O2
Linoleic acid
18:2
50.19
3 Hexadecenoic acid, methyl ester
C17H34O2
Palmitic acid
16:0
11.20
4 Octadecenoic acid, methyl ester
C18H36O2
Stearic acid
18:0
7.70
5 Cis-5, 8, 11, 14-Eicosatetraenoic, methyl ester
C8H16O2
Arachidonic acid
20:0
2.40

Oche et al. 089
Figure 1: X-Ray Diffraction of Non-calcined
MgO/Al2O3/Kaolin Catalyst
Figure 2: X-Ray Diffraction of Calcined MgO/Al2O3/Kaolin
Catalyst
Figure 3: Experimental Setup of the Transesterification
process
Figure 4: Effect of Catalyst Dosage on Biodiesel Yield
Figure 5: Effect of Methanol/Oil ratio on Biodiesel Yield
Figure 6: Effect of Time of Reaction on Yield
Figure 7: Effect of Temperature on Biodiesel Yield
Figure 8: Effect of Catalyst Type on Biodiesel Yield

Figure 9: Effect of Temperature on the Viscous Flow of
PLO, BD1, CD
Figure 10: Effect of Temperature on the Viscosity of
Biodiesel (BD1) and Commercial Diesel (CD) Blends.
Figure 11: FTIR of Pure Luffa aegyptiaca Oil (PLO)
Figure 12: FTIR of Luffa aegyptiaca Biodiesel (BD 1)
Figure 13: FTIR of Commercial Diesel (CD) and Luffa
aegyptiaca Biodiesel (BD1)
Figure 14: Gas Chromatography- Mass Spectrograph of
Pure Luffa aegyptiaca Oil (PLO)

Oche et al. 091
Figure 15: Gas Chromatography- Mass Spectrograph of Luffa aegyptiaca Biodiesel (BD1)

Heterogeneous Transesterification of Luffa aegyptiaca Oil to Biodiesel

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