jo ur nal homep age: www.elsev ier .com/ locate / indcrop
ynthesis of Jatropha curcas oil-based biodiesel in a pulsed loop reactor
zhari M. Syama,∗, Robiah Yunusb, Tinia I.M. Ghazia, Thomas S.Y. Choonga
Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia 43400, Serdang, Selangor Darul Ehsan, MalaysiaInstitute for Advanced Technology, Universiti Putra Malaysia 43400, Serdang, Selangor Darul Ehsan, Malaysia
r t i c l e i n f o
rticle history:eceived 30 April 2011eceived in revised form 21 July 2011ccepted 26 July 2011vailable online 27 August 2011
eywords:
a b s t r a c t
Jatropha curcas oil (JCO) has a high content of free fatty acids and has been used extensively as a feed-stock in biodiesel production. In the present study, the transesterification reaction of JCO to Jatrophacurcas methyl ester (biodiesel) was performed in a continuous pulsed loop reactor under atmosphericconditions. The JCO was pre-treated prior to the reaction to reduce the free fatty acid content to below1% (w/w). The operating parameters of the loop reactor were optimised based on the conversion of theJCO to Jatropha curcas biodiesel and included reaction temperature, molar ratio of oil to MeOH, reaction
time and oscillation frequency. The findings show that the highest reaction conversion of 99.7% (w/w)was achieved using KOH catalyst and 98.8% conversion was obtained using NaOCH3 catalyst. The optimaloperating conditions were a molar ratio of 6:1, an oscillation frequency of 6 Hz, temperature of 60 ◦C,feedstock FFA content of 0.5% (w/w) and only 10 min of reaction time. As a commercial commodity,the physical properties of biodiesel were analysed, and they compared well with the characteristics offossil-based diesel fuel.
. Introduction
The environmental issues surrounding growing carbon diox-de emissions, global warming, declining petroleum fuels reserves,nd rising crude oil prices have resulted in worldwide attentiono biodiesel. With the growth of the human population, more lands needed to produce food for human consumption, which poses
potential challenge to biodiesel production. Jatropha curcas oil is plant-based feedstock that is unsuitable for human consumptionnd could be the best feedstock for alternative renewable energy. Aommon method to produce biodiesel is the transesterification pro-ess or methanolysis, which refers to a catalysed chemical reactionnvolving vegetable oil and MeOH to yield fatty acid methyl ester ashe main product and glycerol as a by-product (Huber et al., 2006;otero et al., 2005; Marchetti et al., 2007), as shown in Eq. (1).
G + 3MeOHCatalyst←→ Glycerol + 3ME (1)
here TG, MeOH and ME denote triglyceride, methanol and methylster, respectively. Transesterification is the preferred method due
o the ease of operation and lower production costs. Even thoughther methods, such as microemulsions, may lower the viscosity ofegetable oils closer to that of petroleum diesel, they contribute to
engine performance problems, such as carbon deposits and lubri-cating oil contamination (Ziejewski et al., 1984).
Currently, many reports on biodiesel production describe syn-thesis methods conducted under batch mode using various typesof reactor configurations, such as plug flow reactors (Helwaniet al., 2009), batch reactors (Darnoko and Cheryan, 2000b), fixedbed reactors (Ni and Meunier, 2007) and stirred tank reactors(Ognjanovic et al., 2009). Continuous pulsed loop reactors andoscillatory flow reactors (OFR) have been tested for biodiesel pro-duction. Harvey et al. (2003) reported that the long residence timesof batch processes led to problems such as high capital costs and theneed for complex control systems. Their findings reported that thecorrelation of cetane number with the degree of conversion was sig-nificant. Cetane number increases with increasing of residence timeand temperature, indicating that the degree of conversion increaseswith these parameters. The acceptable cetane number (45.3) wasachieved at 50 ◦C and 30 min of residence time (Harvey et al., 2003).A pulsed loop reactor is a tubular reactor in which orifice plate baf-fles are equally spaced and a pulsed flow is produced using a pistondrive. This type of reactor is normally used in the fields of heat andmass transfer, residence time distributions, size distributions, flowpatterns and mixing studies (Palma and Giudici, 2003; Reis et al.,2004). The oscillatory flow reactor allows these processes to pro-ceed in a continuous manner, thereby intensifying the process and
improving the economics (Harvey et al., 2003).
The main purpose of this study was to synthesise Jatropha curcasmethyl ester (Jatropha curcas biodiesel) from pre-treated Jatrophacurcas oil (JCO) in a pulsed loop reactor via transesterification. A
Table 1Physical properties of crude Jatropha curcas oil (JCO).
Physical properties Unit Value
Flash point ◦C 210a
Density at 15 ◦C g/cm3 0.91Viscosity at 40 ◦C mm2/s 16.33Calorific value MJ/kg 37.6Pour point ◦C −1.0Water content ppm 915Acid value mg KOH/g 15.78
3BttmpotMtvawpad
2
2
CToShoau(r
0uletwadnia(
2
rso
Iodine value g iod/100 g oil 97
a Pramanik (2003).
.5 l oscillatory flow reactor was designed and fabricated in-house.ecause the free fatty acid content of JCO was always above 10%,he JCO was pre-treated prior to the transesterification process. Inhis study, the synthesis of Jatropha curcas methyl ester (JME) using
ethanol (MeOH) was carried out using two alkaline catalysts:otassium hydroxide (KOH) and sodium methoxide (NaOCH3). Theperating parameters that affect the transesterification reaction inhe pulsed loop reactor are the frequency of oscillation, the ratio of
eOH to JCO, the reaction temperature, and the reaction time. Thus,he objective of this research study was to determine the optimumalues of these operating conditions. All other variables such as themount of catalyst and the free fatty acid content of the feedstockere kept constant at 1% (w/w) and 0.5% (w/w), respectively. Thehysical and chemical properties of Jatropha curcas biodiesel werelso analysed and compared to the characteristics of fossil-basediesel fuel.
. Materials and methods
.1. Materials
JCO was produced using a multi-functional extractor in thehemical Engineering Laboratory, Universiti Putra Malaysia (UPM).he physical properties of JCO are shown in Table 1. Isopropanolf 99.7% purity (Systerm), sulphuric acid of 98% purity (Fishercientific), phenolphthalein of 1% purity (Systerm) and sodiumydroxide of 99% purity (Systerm) were used in the pre-treatmentf JCO. The catalysts for the transesterification were KOH (Systerm)nd NaOCH3 (Fluka). MeOH of 99.8% purity (R&M Chemical) wassed for both esterification and transesterification. Ethyl acetateFluka) and BSTFA (ACROS organics) were used for gas chromatog-aphy (GC) sample preparation.
Experiments were conducted using a pulsed loop reactor (ID,.0635 m and H, 1.1 m) that was connected to the other processnits and feedstock storage tanks as shown in Fig. 1. The pulsed
oop reactor was designed and fabricated in-house. The reactor wasquipped with a set of baffles and consisted of two vertically posi-ioned jacketed tubes. The overall internal volume of the reactoras 0.0035 m3. The temperature in the feed vessel was controlled
nd maintained by a thermocouple. The frequency of the pistonrive ranged from 1 to 9 Hz. Other peripherals were a separator fun-el, tanks and the related glassware. The analytical equipment used
n this study included an autotitrator (785 DMP Tritino, Metrohm), gas chromatograph (Agilent 6890 Series), a pour point testerPetrotest) and others.
.2. Experimental procedure
The pre-treated JCO was prepared as the reaction feedstock. Theeactor was initially charged with 2.0 kg of the pre-treated feed-tock and heated to 60 ◦C using a circulation outer jacket. A mixturef MeOH and catalyst was then pumped into the reactor after which
d Products 37 (2012) 514– 519 515
the reaction was assumed to commence. The unreacted alcohol andcatalyst were removed via a 2-steps purification stage. The alco-hol was recovered by distillation and the catalyst was removed bywashing the methyl ester with two volumes of water mixed with afew drop of phosphoric acid. The schematic diagram of the pulsedloop reactor is illustrated in Fig. 1.
2.3. Analytical methods
The free fatty acid content of the feedstock was determined byperforming an acid-base titration using a standard alkali solutionof 0.1 N (Lin et al., 1995).
Analysis of the reaction products was performed with a gaschromatograph (Agilent 6890 Series) using capillary column SGE12 m ×0.53 mm, 0.15 �m ID column HT5 (SGE, Australia, Pty. Ltd.)with hydrogen at 26.7 ml min−1 as a carrier gas and a split ratioof 1:1. The oven temperature was initially set at 80 ◦C for 3 minand then increased to 340 ◦C at a rate of 6 ◦C min−1 and held foranother 6 min. The injector and detector temperature were 300 ◦Cand 360 ◦C, respectively (Yunus et al., 2002).
The kinematic viscosity of Jatropha curcas biodiesel was mea-sured using the Cannon–Fenske routine viscometer for transparentliquids. The measuring procedure followed ASTM D445 (1977). Thedensity of Jatropha curcas biodiesel was measured using the ana-lytical Balance Mettler Toledo XP204. The measuring procedurefollowed ASTM D4052 (1977). The acid number of Jatropha curcasbiodiesel was measured using auto titration, the 785 DMP Titrino,Metrohm. ASTM D664 (1977) was used as the analysis procedure.The pour point of Jatropha curcas biodiesel was measured usingthe Cloud and Pour Point Tester, Petrotest. The test procedure wasreferred to ASTM D97 (1977). The cloud point of Jatropha curcasbiodiesel was using the Cloud and Pour Point Tester, Petrotest.The test method followed ASTM D2500 (1977). The water con-tent of Jatropha curcas biodiesel was measured using the 737 KarlFischer Coulometer, Metrohm. ASTM D2709 (1977) was used fortesting procedure. The carbon residue of Jatropha curcas biodieselwas measured using the Conradson Carbon Residue apparatus. Thetest method followed ASTM D189 (1977). Calorific value of Jatrophacurcas biodiesel was determined by using Bomb Calorimeter, Parr.The test was carried out under ASTM D240 (1977). The flash point ofJatropha curcas biodiesel was determined by using The Flash PointTester, Petrotest PM4 by means of ASTM D93 (2003). While, thetotal glycerol content was determined using ASTM D6584 (2003).
Iodine value of Jatropha curcas biodiesel was measured usingauto titration, the 785 DMP Titrino, Metrohm. Weigh the samplein the glass weighing scoop. Place the scoop in a 500 ml flask. Add15 ml of CCl4 to dissolve the fat. Add exactly 25 ml of the Wijs solu-tion and place the flask in the dark for 1 h. After standing, add 20 mlof the potassium iodine solution and 150 ml of water. Titrate withthe sodium thiosulphate solution until the yellow colour (Lin et al.,1995).
3. Results and discussions
3.1. Pulsed loop reactor
A pulsed loop reactor is an oscillatory flow tubular reactor inwhich orifice plate baffles are equally spaced and a pulsed flow isproduced using a piston drive. It is a new type of continuous reac-tor that generates a superimposed flow through an interaction withthe baffles and the oscillatory motion of the fluid. Hence, it intensi-
fies radial mixing, enhances mass and heat transfer and improvesthe reaction time profile. Each baffle functions as a stirred tank, soif there are enough baffles in series, a good approximation of plugflow can be achieved. Harvey et al. (2003) reported that a surface
516 A.M. Syam et al. / Industrial Crops and Products 37 (2012) 514– 519
ulsed
gampddo
3
tmrfuitn
R
w(e
cflptw
date, there has been no report on the effect of oscillation frequencyin biodiesel synthesis.
Fig. 1. Schematic of p
eometry transverse to the oscillatory flow produced a uniformnd efficient mixing pattern. The optimal geometry for uniformixing in the loop reactor was determined based on the princi-
le of maintaining geometric and dynamic similarity using variousimensionless groups. It has been shown that the residence timeistribution depends on the interaction of the net and imposedscillatory flows (Brunold et al., 1989).
.2. Effect of oscillation frequency
Because the mixing process in this reactor is achieved throughhe superimposed oscillatory motion, the frequency of the piston
ovement played an important role in speeding up the rate ofeaction. The oscillatory motion facilitates excellent mass trans-er and energy transfer once the reactants have reached the bafflesnder the superimposed flow condition. As shown in Fig. 2, there
s a direct correlation between the biodiesel yield and the oscilla-ion frequency, which is represented by the oscillatory Reynoldsumber (Reo), as illustrated in Eq. (2).
eo = �2�fxoD
�(2)
here � is the fluid density (kg m−3), f is the oscillation frequencys−1), �o is the centre-to-peak amplitude (mm), D is the tube diam-ter (mm) and � is the fluid viscosity (mm2 s−1).
When Reo was greater than 2100, the maximum yield of Jatrophaurcas biodiesel was obtained at 60 ◦C. The nature of the oscillatory
ow depended significantly on the oscillatory Reynolds number,articularly the frequency of oscillation. This phenomenon is due tohe formation of eddy and ejection currents at the centre of tube andas reported by Mackay et al. (1991) who conducted an axisym-
loop reactor system.
metric simulation of a baffle tube and visualised the resulting flow.The rate of mass transfer is accelerated by decreasing the surfacetension of the liquid due to thermodynamic effects. Below 6 Hz (Reo
between 1400 and 1700), the yield of biodiesel was very low. Underthese oscillation frequencies, fluid mixing decreased due to fewernumbers of flow vortices, which resulted in a lower mass transferrate. However, at oscillation frequencies above 6 Hz (Reo > 2100),no significant increase in biodiesel yield was recorded. Beyond thereaction equilibrium (6 Hz), the maximum reaction conversion willnot be affected unless a new equilibrium position is attained. To
Fig. 2. Effect oscillation Reynolds number, Reo on reaction conversion.
A.M. Syam et al. / Industrial Crops and Products 37 (2012) 514– 519 517
Fa
3
tcretEriMm
(oowoafipwJpdodi
nm
TP
ig. 3. Effect of molar ratio on percent conversion triglycerides at various temper-tures.
.3. Effect of reactants molar ratio
The molar ratio of the excess reactant to the limiting reac-ant is one of the most important variables affecting the percentonversion of JCO to JME. In this reaction, MeOH was the excesseactant and JCO was the limiting reactant. The reaction stoichiom-try requires three moles of MeOH to react with one mole of JCOo yield three moles of JME and one mole of glycerol, as shown inq. (1). A large excess of alcohol is usually required to drive theeaction to the product side. The maximum molar ratio employedn this experimental work was 7:1. The effect of the molar ratio of
eOH to JCO on the yield of methyl ester was studied at variousole ratios of MeOH to JCO.Based on the reaction stoichiometry, 99% conversion of JCO
2000 g or 2.30 moles) will result in the production of 6.89 molesf JME. The maximum reaction yield was achieved at a molar ratiof 6:1, as shown in Fig. 3. As seen in the graph, a lower conversionas observed at lower molar ratios since the percent conversion
f triglycerides was less than 98%. This observation indicates that higher molar ratio of MeOH to JCO results in better transesteri-cation reaction. As stated earlier, because the transesterificationrocess is a reversible reaction, an increase in the amount of MeOHill drive the reaction to the right and promote the formation of
ME. The importance of the excess MeOH in the transesterificationrocess has been reported often in the literature because MeOHrives the forward reaction and is key to ensuring the formationf the desired methyl ester product. Additionally, it promotes theissociation of intermediate compounds once the initial complex
s formed.Fig. 3 also indicates that at a higher ratio (7:1), the results do
ot show any improvement in terms of reaction yield. The maxi-um conversion to methyl ester occurred at 6:1 molar ratio. Thus,
able 2hysical and chemical properties of biodiesel and comparison with diesel fuel characteris
Properties Method
Kinematics viscosity (mm2/s) ASTM D445
Density (kg/m3) ASTM D4052
Acid number (mg KOH/g oil) ASTM D664
Pour point (◦C) ASTM D97
Cloud point (◦C) ASTM D2500
Water content (%) ASTM D2709
Carbon residue (% mass) ASTM D189
Iodine value (g odine/100 g) PORIM
Calorific value (MJ/kg) ASTM D240
Flash point (◦C) ASTM D93
Total glycerol ASTM D6584
b (Tiwari et al., 2007).
Fig. 4. Effect of residence time on percent conversion of triglycerides at 60 ◦C.
the additional amounts of MeOH available at the 7:1 ratio had noinfluence on the yield. Moreover, the presence of MeOH increasesthe solubility of glycerol in methyl ester, which interferes with thefinal separation of reaction products (Fillieres et al., 1995).
3.4. Effect of residence time
In this study, the effect of residence time on the product yieldwas investigated to determine the optimum reaction time to obtainthe highest conversion to Jatropha curcas methyl ester. The previouswork carried out by Noureddini et al. (1998) concluded that thereaction time was the controlling factor in determining the yield ofmethyl ester.
The rate of the transesterification reaction depends on the timeof reaction, as shown in Fig. 4. The rate of conversion at 60 ◦C wasvery high during the first 5 min and slowed down thereafter until itreached the equilibrium in 10 min. Approximately 60% of the con-version was achieved during the first 5 min and another 5 min tocomplete the reaction. The use of pulsed reactor enabled the reac-tion to reach maximum conversion (99%) in 10 min as compared to30 min required by the batch reactor (Jena et al., 2010). This resultshows the advantage of using oscillatory flow reactors over batchreactors: the reaction time can be reduced by 50%. In terms of prod-uct yield, this reactor could convert 99% of the JCO into Jatrophacurcas methyl ester. Similar work on an oscillatory flow reactorfor the transesterification of vegetable oil using hydroxide cata-lyst required a longer reaction time of 30 min to reach about 90%conversion to methyl ester (Harvey et al., 2003). While He et al.(2007) reported that up to 77% of biodiesel yield was obtained in25 min using supercritical methanol. The optimal process param-eters for supercritical methanol process were 310 ◦C, 35 MPa, and
40:1 molar ratio alcohol to oil.
As mentioned earlier, the oscillatory mixing induced by the pis-ton promoted mass transfer between the liquids, which furtheraccelerated the rate of reaction. This factor reduced the reaction
tics.
Jatropha curcas biodiesel Dieselb
4.33 2.6866 850
0.738 –−10 −15−6 −10
0.004 0.020.03 0.17
99 9438.72 4273 68
0.3 –
518 A.M. Syam et al. / Industrial Crops and Products 37 (2012) 514– 519
Fe
tp(ftbtmiap1
3
abeaeet(JtmmttltoW0cTf2
malts
ig. 5. Effect of catalyst types and temperature on percent conversion of triglyc-rides.
ime and increased the yield. Hewgill et al. (1993) reported a com-rehensive study to measure values of mass transfer coefficientskLa) for an oscillatory flow in a baffled tube. It indicated that a sixold increase in kLa values was observed. A typical increase of massransfer coefficient values in an oscillatory flow mixer was foundy Ni et al. (1995). This showed that the fluid oscillation in baffledubes enhanced the mass transfer (Gupta et al., 1982). This factor
ay contribute to the reduction in the reaction time and increasen product yield. Consequently, oscillatory flows have gained muchttention in many engineering applications, including the use ofulsatile flow to increase mass transfer in reactors (Cognet et al.,995).
.5. Effect of reaction temperature and catalyst type
Previous studies on transesterification of vegetable oils andnimal fats suggested that the conversion of triglycerides intoiodiesel may be affected by the catalyst amount. Based on anarlier study using a batch reactor, the optimum percentage of cat-lyst was found to be 1% (w/w), and this amount was used for allxperiments in this study (Syam et al., 2009). In this study, theffects of different types of catalyst on product yield were inves-igated using potassium hydroxide (KOH) and sodium methoxideNaOCH3). Based on Fig. 5, it can be observed that the yield ofatropha curcas methyl ester (biodiesel) increased steadily withemperature, for both KOH and NaOCH3 catalysts. For an endother-
ic reaction, higher temperature results in higher conversion to theethyl ester product. This finding is supported by the kinetics study
hat showed the dependency of the rate constants on the reactionemperature. The kinetics analysis of the data obtained from pulsedoop reactor confirmed that the reaction follows first order reac-ion model as shown in Fig. 6. The rate constants for conversionf triglycerides to diglycerides ranged from 0.428 to 0.606 min−1.hile, the rate constants for the formation of biodiesel ranged from
.256 to 0.385 min−1. The activation energies for the transesterifi-ation of Jatropha curcas-based oils were 58.916–69.619 kJ mol−1.hese results compared well with the kinetics parameters obtainedrom the study conducted in a batch reactor (Yunus and Syam,010).
Fig. 5 also shows that increasing the temperature to 60 ◦C only
arginally affects the yield of methyl ester for both catalysts. In
ddition, it was observed that using the NaOCH3 catalyst, slightlyower yield of Jatropha curcas biodiesel was obtained comparedo KOH catalyst. This proved that potassium is more reactive thanodium and hydroxyl ion is more basic than methoxide ion.
Fig. 6. Plot of first order kinetics model for transesterification of JCO.
3.6. Analysis of product properties
To meet the requirement of biodiesel specifications namelyASTM D6751, the analysis of the physical and chemical propertiesof the Jatropha curcas biodiesel were performed to compare againstthe diesel fuel standards. The selected physical and chemical prop-erties were kinematic viscosity, density, acid number, pour point,cloud point, water content, carbon residue, iodine value, calorificvalue, total glycerol and flash point. These analyses followed theASTM standard methods as shown in Table 2.
Table 2 shows the properties of Jatropha curcas biodiesel and thecomparison to diesel fuel characteristics. In this study, the resultsshow that the heating value of Jatropha curcas biodiesel is compa-rable to that of the diesel. In addition, the carbon residue is lowerand the flash point is higher than the diesel fuel. Even though thekinematic viscosity of Jatropha curcas biodiesel is very much higherthan that of the diesel fuel, the pour and cloud points are still com-parable.
4. Conclusion
In this study, the synthesis of Jatropha curcas biodiesel usinga pulsed loop reactor at a pulsation frequency of 6 Hz producedbiodiesel with more than 99% (w/w) content of methyl ester in ashort duration of 10 min. This result was achieved using KOH as acatalyst, a molar ratio of MeOH to JCO of 6:1 and a reaction tem-perature of 60 ◦C. KOH is a better catalyst than NaOCH3 because thelatter produces less yield of Jatropha curcas biodiesel. The recom-mended amount of KOH catalyst was 1% (w/w). In this study, theanalysis of product characteristics showed that the properties ofJatropha curcas biodiesel are comparable to that of the petroleumdiesel.
Acknowledgments
This research work was conducted with the financial supportof FRGS (Fundamental Research Grant Scheme) from Minister ofScience, Technology & Innovation, Malaysia.
References
ASTM D445, 1977. Standard test method for kinematic viscosity of transparent andopaque liquids.
ASTM D4052, 1977. Standard test method for density, relative density, and API
gravity of liquid.
ASTM D664, 1977. Standard test method for neutralization number by potentiomet-ric titration.
ASTM D97, 1977. Standard test method for pour point of petroleum oils.ASTM D2500, 1977. Standard test method for cloud point of petroleum oils.
ps an
A
A
A
A
A
B
C
D
F
G
H
H
H
H
H
J
A.M. Syam et al. / Industrial Cro
STM D2709, 1977. Standard test method for water and sediment in distillate fuelsby centrifuge.
STM D189, 1977. Standard test method for conradson carbon residue of petroleumproducts.
STM D240, 1977. Standard test of combustion of liquid hydrocarbon fuels by bombcalorimeter.
STM D93, 2003. Standard test method for flash point by Pensky–Marten closed cuptester.
STM D6584, 2003. Standard test method for determination of total monoglyceride,total diglyceride, and free and total glycerine in B-100 biodiesel methyl ester bygas chromatography.
runold, C.R., Hunns, J.C.B., Mackley, M.R., Thompson, J.W., 1989. Experimentalobservation on flow patterns and energy losses for oscillatory flow in ductscontaining sharp edges. Chem. Eng. Sci. 44, 1227–1244.
ognet, P., Berlan, J., Lacoste, G., Fabre, P.L., Jud, J.M., 1995. Application of metallicfoams in an electrochemical pulsed flow reactor. Part I. Mass transfer perfor-mance. J. Appl. Electrochem. 25, 1105–1112.
arnoko, D., Cheryan, M., 2000b. Kinetics of palm oil transesterification in a batchreactor. J. Am. Oil Chem. Soc. 77, 1263–1267.
illieres, R., Benjelloun-Mlayah, B., Delmas, M., 1995. Ethanolysis of rapeseed oil:quantitation of ethyl esters, mono-, di-, and triglycerides and glycerol by highperformance size-exclusion Chromatography. J. Am. Oil Chem. Soc. 72, 427–432.
upta, S.K., Patel, R.D., Ackerberg, R.C., 1982. Wall heat/mass transfer in pulsatileflow. Chem. Eng. Sci. 37, 1727–1739.
arvey, A.P., Mackley, M.R., Seliger, T., 2003. Process intensification of biodiesel pro-duction using a continuous oscillatory flow reactor. J. Chem. Technol. Biotechnol.78, 338–341.
e, H., Wang, T., Zhu, S., 2007. Continuous production of biodiesel fuel from veg-etable oil using supercritical methanol process. Fuel 86, 442–447.
elwani, Z., Othman, M.R., Aziz, N., Fernando, W.J.N., Kim, J., 2009. Technologiesfor production of biodiesel focusing on green catalytic techniques. Fuel Process.Technol. 90, 1502–1514.
ewgill, M.R., Mackley, M.R., Pandit, A.B., Pannu, S.S., 1993. Enhancement of gas-liquid mass transfer using oscillatory flow in baffled tube. Chem. Eng. Sci. 48,799–809.
uber, G.W., Iborra, S., Corma, A., 2006. Synthesis of transportation fuels frombiomass: chemistry, catalysts, and engineering. Chem. Rev. 106, 4044–4048.
ena, P.C., Raheman, H., Kumar, G.V.P., Machavaram, R., 2010. Biodiesel productionfrom mixture of mahua and simarouba oils with high free fatty acids. BiomassBioenergy 34, 1108–1116.
d Products 37 (2012) 514– 519 519
Lin, S.W., Sue, T.T., Ai, T.Y., 1995. PORIM Test Methods, first ed. MPOB, Kuala Lumpur.Lotero, E., Liu, Y., Lopez, D.E., Suwannakarn, K., Bruce, D.A., Goodwin Jr., J.G., 2005.
Synthesis of biodiesel via acid catalysis. Ind. Eng. Chem. Res. 44, 5353–5363.Mackay, M.E., Mackley, M.R., Wang, Y., 1991. Oscillatory flow within tubes contain-
ing wall or central baffles. Chem. Eng. Res. Des. 69, 506–513.Marchetti, J.M., Miguel, V.U., Errazu, A.F., 2007. Possible methods for biodiesel pro-
duction. Renew. Sustain. Energy Rev. 11, 1300–1311.Ni, J., Meunier, F.C., 2007. Esterification of free fatty acids in sunflower oil over
solid acid catalysts using batch and fixed bed-reactors. Appl. Catal. A: Gen. 333,122–130.
Ni, X., Gao, S., Cumming, R.H., Pritchard, D.W., 1995. A comparative study of masstransfer in yeast for a batch pulsed baffled bioreactor and a stirred tank fer-menter. Chem. Eng. Sci. 50, 2127–2136.
Noureddini, H., Harkey, D., Medikonduru, V.A., 1998. Continuous process for theconversion of vegetable oils into methyl ester of fatty acids. J. Am. Oil Chem.Soc. 75, 1775–1783.
Ognjanovic, N., Bezbradica, D., Knezevic-jugovic, Z., 2009. Enzymatic conversion ofsun flower oil to biodiesel in a solvent-free system: process optimization andthe immobilized system stability. Bioresour. Technol. 100, 5146–5154.
Palma, M., Giudici, R., 2003. Analysis of axial dispersion in an oscillatory-flow con-tinuous reactor. Chem. Eng. J. 94, 189–198.
Pramanik, K., 2003. Properties and use of Jatropha curcas oil and diesel fuel blendsin compression ignition engine. Renew. Energy 28, 239–248.
Reis, N., Vicente, A.A., Teixeira, J.A., Mackley, M.R., 2004. Residence time and mixingof a novel continuous oscillatory flow screening reactor. Chem. Eng. Sci. 59,4967–4974.
Syam, A.M., Yunus, R., Ghazi, T.I.M., Yaw, T.C.S., 2009. Methanolysis of Jatropha oil inthe presence of potassium hydroxide catalyst. J. Appl. Sci. 9 (17), 3161–3165.
Tiwari, A.K., Kumar, A., Raheman, H., 2007. Biodiesel production from Jatropha oil(Jatropha curcas) with high free fatty acids: an optimized process. Biomass Bioen-ergy 31, 569–575.
Yunus, R., Fakhru’l-Razi, A., OOI, T., Basri, S.A., 2002. Simple capillary column gaschromatography method for analysis of palm oil-based polyol esters. J. Am. Oil.Chem. Soc. 79, 1075–1080.
Yunus, R., Syam, A.M., 2010. Kinetics of transesterification of Jatropha curcas-based
triglycerides with an alcohol in the presence of alkaline catalyst. In: Proceedingsof 1st IEEE Conference of INREC’10, 21–24 March, 2010, Amman, Jordan, pp. 1–4.
Ziejewski, M., Kaufman, K.R., Schwab, A.W., Pryde, E.H., 1984. Diesel engine eval-uation of a nonionic sunflower oil-aqueous ethanol microemulsion. J. Am. Oil.Chem. Soc. 61, 1620–1626.
