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Kinetics of the transesterification ofJatropha curcas triglyceride with analcohol in the presence of an alkalinecatalystRobiah Yunus a & Azhari Muhammad Syam aa Department of Chemical and Environmental Engineering,Universiti Putra Malaysia, Serdang, Malaysia

Available online: 14 Dec 2011

To cite this article: Robiah Yunus & Azhari Muhammad Syam (2011): Kinetics of thetransesterification of Jatropha curcas triglyceride with an alcohol in the presence of an alkalinecatalyst, International Journal of Sustainable Energy, 30:sup2, S175-S183

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International Journal of Sustainable EnergyVol. 30, Suppl. No. S2, 2011, S175–183

Kinetics of the transesterification of Jatropha curcas triglyceridewith an alcohol in the presence of an alkaline catalyst

Robiah Yunus* and Azhari Muhammad Syam

Department of Chemical and Environmental Engineering, Universiti Putra Malaysia, Serdang, Malaysia

(Received 6 April 2011; final version received 28 September 2011)

Jatropha curcas alkyl ester can be produced via a transesterification reaction of J. curcas triglyceride (JCT)using an alkaline catalyst with an alcohol. In this study, the reaction was carried out in a batch reactorunder various operating conditions. The kinetics study of the transesterification of JCT with methanol wasconducted at various temperatures ranging from 50 ◦C to 65 ◦C. The conversion of triglyceride (TG) anddiglyceride (DG) into biodiesel followed a first-order mechanism, while the conversion of monoglycerideinto biodiesel occurred too fast, thus assuming a non-limiting step. The reaction rate constants weredetermined and then plotted against temperatures for the determination of activation energies. The valuesof kTG ranged from 0.11 to 0.17 min−1 and the values of kDG ranged from 0.07 to 0.20 min−1. The activationenergies for the transesterification of TG/DG with methanol were 27.38 and 46.72 kJ mol−1, respectively.The high Ea values indicate that the transesterification of J. curcas is sensitive to temperature changes.

Keywords: kinetics of transesterification; Jatropha curcas triglyceride; alkaline catalyst

1. Introduction

There is growing interest in the use of Jatropha curcas triglyceride (JCT) as the raw material forproducing biodiesel due to its ability to grow in semi-arid lands with low nutrient requirements intropical or subtropical countries and little maintenance and as it is a multi-purpose species withmany attributes and considerable potentials (Tapanes et al. 2008). In order to avoid the disturbanceto food supply, the use of non-edible oils as biodiesel feedstock has been studied rigorously. JCT isone of the non-edible biodiesel feedstocks that have received enormous attention from researchersworldwide. Due to the environmental concerns, this non-edible oil can be a practical substitute forfossil-based fuels to counter greenhouse gas accumulation (Openshaw 2000). Another potentiallow-cost feedstock for biodiesel production is musk seed oil (Cucumis melo) (Rashid et al. 2011).

Transesterification of vegetable triglyceride (TG) (oil) with simple alcohols constitutes a com-mon method for producing alkyl ester, commonly known as biodiesel. In general, there are twomethods of transesterification: one with and another without the assistance of a catalyst (Kus-diana and Saka 2001). The transesterification with a catalyst can be performed using acidic oralkaline catalysts (Komers et al. 2002, Tanguy et al. 2006, Vicente et al. 2006, Baig and Ng 2010).

*Corresponding author. Email: robiah@eng.upm.edu.my

ISSN 1478-6451 print/ISSN 1478-646X online© 2011 Taylor & Francishttp://dx.doi.org/10.1080/14786451.2011.628749http://www.tandfonline.com

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The method without the assistance of a catalyst is used in the transesterification of vegetable TGusing supercritical methanol. In terms of reaction rate, Freedman et al. (1986) reported that analkali-catalyzed transesterification proceeds at considerably faster rates than an acid-catalyzedtransesterification. The variables affecting the transesterification, such as molar ratio of alcoholto oil, type of catalyst, temperature and presence of impurities such as free fatty acid (FFA) andmoisture, have been investigated intensively (Vicente et al. 2006). To guarantee a high yield ofalkyl ester, the FFA content in the oil feedstock should not be more than 1% (Freedman et al. 1984,Liu 1994). Otherwise, the saponification will occur and the separation of the products would beexceedingly difficult.

The study on the kinetics of transesterification provides parameters that can be used to pre-dict the extent to which the reaction has occurred at any time under certain operating conditions(Darnoko and Cheryan 2000). According to Noureddini and Zhu (1997), among several kineticsstudies published on the transesterification of simple esters, only a few are concerned with thetransesterification using an alkaline catalyst. The overall reaction of transesterification is as fol-lows. The reaction stoichiometry (Scheme 1) indicates that three moles of alcohol are needed toconvert one mole of TG completely into one mole of glycerol (GL) as a by-product and threemoles of alkyl ester. However, in practice, the reaction requires many folds of excess of an alco-hol derivative to shift the reaction to the product side and to prevent the formation of undesiredintermediate products via competing reactions.

(1)

Scheme 1. Overall reaction for transesterification of triglyceride.

In Scheme 1, R1, R2 and R3 represent alkyl groups from C14 to C24 (Baig and Ng 2010). In thispaper, the kinetics parameters of the transesterification reaction between the JCT and methanolare investigated. The parameters covered in this study are the reaction order, the rate constant andactivation energy for the conversion of the TG into methyl ester (biodiesel).

2. Materials and methods

The experiments involved product synthesis, product analysis using gas chromatography (GC) asshown in Figure 1 and development of reaction kinetics.

2.1. Materials

JCT was produced from the crushed J. curcas seeds using a multi-functioned extractor model.The J. curcas seeds were supplied by Paskon Enterprise. Prior to the pretreatment step, the FFAcontent of the crude JCT was 19.3%. The feedstock with a high FFA content is not suitable tobe used directly in biodiesel production using an alkaline catalyst (Baig and Ng 2010). Thus, thecrude JCT should undergo a pretreatment process to lower the FFA content to an acceptable level.After the pretreatment process, the treated JCT, which contained 0.6% of FFA, was applied as the

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Figure 1. Chromatogram of the kinetics sample at a reaction time of 10 min.

transesterification feedstock. Isopropanol of 99.7% purity (Systerm), phenolphthalein of 1% purity(Systerm) and NaOH of 99% purity (Systerm) were used for the determination of FFA contentof JCT. For the acidic pretreatment step, methanol of 99.8% purity (Systerm) and sulphuric acid(H2SO4) of 95–98% purity (Fisher Scientific) were employed. Methanol and potassium hydroxide(KOH) of 95–98% purity (Systerm) were also used in the transesterification reaction. Ethyl acetate,99%, and N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA) (Fluka) were applied for samplepreparation for the GC (Agilent 6890 Series) analysis.

2.2. Methods

2.2.1. Experimental procedures

In this study, a two-step acid–alkali-catalyzed transesterification was carried out using the follow-ing methods. First, in the acid pretreatment step, the crude JCT was added into the batch reactorand heated to the specified temperature (60 ◦C). Sulphuric acid (H2SO4) (1% w/w based on theJCT weight) was mixed with methanol and heated to 55 ◦C and then added to the reactor con-taining the heated JCT. The reaction temperature was maintained at 60 ◦C. After the completionof the reaction, the mixture was allowed to settle down for 2 h and the methanol–water fractionat the top layer was removed. The traces of H2SO4 were neutralized using an alkaline solution(NaOH) prior to the FFA analysis and the alkali-catalyzed transesterification. The pretreated JCTwas then used as the feedstock for the subsequent transesterification reaction.

The transesterification reaction was performed in a 500 ml batch reactor equipped with a ther-mometer, a sampling port and a reflux condenser under atmospheric conditions. The condenserwas connected to a water line, and the reactor was immersed in an oil bath and was under constantstirring brought about by the magnetic stirrer. KOH was selected as the catalyst in this step. Fivesets of kinetics data were collected for four different reaction temperatures, namely 50 ◦C, 55 ◦C,60 ◦C and 65 ◦C, respectively. The sample was taken at the specified time and kept in a small vial.Then, the sample was placed in an ice bath to avoid further reaction prior to the GC analysis.Afterwards, for the purpose of GC analysis, approximately 0.03 ± 0.005 g of sample was weighedin a 5 ml vial and diluted with 1.0 ml of ethyl acetate. The sample was swirled for few minutes todissolve the mixture. BSTFA, 0.5 ml, was added to the mixture, swirled and then transferred to awater bath at 40 ◦C for 10 min (Yunus et al. 2002).

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2.2.2. Analytical procedure

The FFA content of the sample was determined using an acid–base titration technique. A standardsolution of 0.1N sodium hydroxide (NaOH) was used. The titration method involved the followingsteps. The neutralized isopropanol was prepared by placing 50 ml isopropanol in a flask and thesolution was brought to a boil on a hot plate. About 0.5 ml of phenolphthalein was added andneutralized by dropwise addition of 0.1N sodium hydroxide till the formation of a faint pinkcolour and later a permanent pink colour. To prepare the sample for FFA analysis, about 2.5 gof the sample was weighed in an Erlenmeyer flask and then mixed with 50 ml of the neutralizedsolvent. The flask was placed on the hot plate and the temperature was regulated to about 40 ◦C.The sample was shaken gently while titrating with the standard solution until the developmentof the first permanent colour. The colour must persist for 30 s (Lin et al. 1995). The analysis wasdone at least three times for each analysed sample.

The GC analysis was conducted according to the method established by Yunus et al. (2002).The separation was carried out using a capillary column, SGE, 12 m × 0.53 mm, and 0.15 μmID column HT5 (SGE Pty. Ltd., Australia) with hydrogen at 26.7 ml/min as a carrier gas andsplit 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 temperatureswere 300 ◦C and 360 ◦C, respectively.

3. Results and discussion

3.1. Parent oil (JCT) characteristics

The characteristics of JCT are as follows: viscosity at 40 ◦C, 48.55 mm2 s−1; density, 0.94 g cm−3;iodine value, 99; FFA, 19.3%; pour point, −2 ◦C; and water content, 920 ppm.

3.2. Kinetics of the transesterification of JCT

The conversion of JCT into a fatty acid methyl ester was examined via GC analysis. The molarratio of methanol to JCT and the amount of catalyst were fixed at 6:1 and 1.0% w/w, respectively,while the reaction temperature was varied accordingly. The sampling was done at certain timeintervals starting from 1 to 60 min. The experiments were carried out to determine the reactionorder, the rate constant and the activation energy for the conversion of JCT into methyl ester.

In order to correlate the experimental data and to quantify the effects of temperature and reactiontime, the experimental results were analysed further for the reaction kinetics. In a similar study,Diasakou et al. (1998) proposed the transesterification reaction to be divided into three steps asshown in Scheme 2. TG reacts with methanol to produce diglyceride (DG), and then DG reactsfurther to produce monoglyceride (MG). Finally, MG reacts with methanol to produce GL as aby-product. At each reaction step, one molecule of methylated compound is produced for eachmolecule of methanol consumed.

TG + MeOH ←→ DG + ME (2)

DG + MeOH ←→ MG + ME (3)

MG + MeOH ←→ GL + ME (4)

Scheme 2. Stepwise reaction for transesterification of triglyceride.

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Figure 2. Composition of the reaction products during the transesterification of JCT (at 60 ◦C, molar ratio of 6:1, catalystamount of 1% w/w of KOH).

In this study, the experimental results showed that the rate of the intermediate reaction shown inEquation (4) is very fast, thus the reactions are governed only by reactions shown in Equations (2)and (3). These are called the rate-limiting steps and will be the ones which control the kineticsof the reaction. Based on these assumptions, a simpler mathematical equation can be defined byignoring the intermediate reactions involving MG.

The progress of the transesterification reaction of JCT with methanol is shown in Figure 2. Thereaction was carried out at 60 ◦C, using a molar ratio of JCT to methanol of 6:1 and a catalystamount of 1% w/w. During the initial stage of the reaction, the yield of J. curcas methyl ester wasproportional to the rate of JCT conversion and finally reached the equilibrium in about 20 min. Theincrease in methyl ester concentration was in tandem with the decrease in the JCT concentration.The JCT was completely converted into methyl ester and by-products at the end of the reaction.The maximum formation of the product, methyl ester, coincided with the point at which thefeedstock JCT was completely consumed, that is, 20 min.

The reaction between the JCT and methanol is postulated to begin with the attachment of thealkoxide ions on the carbonyl group of JCT, which results in the formation of a tetrahedral interme-diate. Later on, the intermediate is converted into the final products, J. curcas methyl ester and GL.

3.3. Determination of rate constant

The rate constant of a reaction can be determined based on the increase in the amount of a productor alternatively based on the decrease in the amount of the limiting reactant. The determinationof a rate constant also depends on the order of the reaction. Using experimental data, the correctorder can be determined by the rate equation which best fits the linear requirement. Once the orderof the reaction is established, the rate constant is estimated from the slope of the linear plot. Therate of the reaction at any time t is given by the following equation:

Rate = −d(TG)

dt, (5)

where TG and t denote the triglyceride (JCT) concentration and time, respectively. However, in thisstudy, the transesterification reaction using the potassium hydroxide catalyst occurred very fast thatthe intermediate reaction given as Equation (4) was assumed to be negligible. This phenomenon isevidenced from the GC chromatograms (Figure 1), where the concentration of MG instantaneouslydisappears after a few minutes of the reaction. In addition, the use of excess methanol minimizes the

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Figure 3. First-order kinetics model for the transesterification of JCO with methanol at various temperatures.

occurrence of a backward reaction. Figure 3 shows that the transesterification of JCT with methanolfollows a first-order kinetics model because all the plots of ln TG versus t are straight lines.

The best kinetics model for this study appears to follow the first-order kinetics model, especiallyduring the initial part of the reaction (Figure 3). In order to test this hypothesis, the experimentalkinetics data were fitted to the first-order kinetics model. As discussed earlier, the intermediatereaction involving MG occurred very fast and thus the three steps can be simplified to two stepsas described herein. In this study, TG concentration (JCT) was chosen to describe the reactionkinetics. The rate constant of the reaction was derived by integrating Equation (5) to yield

−∫ TG

TG0

d(TG)

(TG)= kTG

∫ t

0dt, (6)

− ln[TG]TGTG0

= kTG[t]t0, (7)

ln(TG0)

(TG)= kTGt, (8)

kTG = 1

tln

(TG0)

(TG), (9)

where kTG is the overall rate constant for JCT, t is the time of the reaction and TG0 is the initialTG concentration. A plot of ln (TG0/TG) versus reaction time (t) will be a straight line if thefirst-order model from Equation (8) is valid. Figure 3 shows such plots at temperatures of 50 ◦C,55 ◦C, 60 ◦C and 65 ◦C. The slope is kTG with the units given in min−1. The values of kTG and itscorresponding correlation coefficient are given in Table 1. In a similar study, Tapanes et al. (2008)reported that the k values increase with temperature. However, when the data were plotted using

Table 1. Rate constant, kTG, for the reaction betweenmethanol and JCT.

Temperature (◦C) kTG (first order) (min−1) R2

50 0.11 0.9455 0.12 0.9760 0.15 0.9965 0.17 0.99

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the second-order model, the graph did not form a straight line. Therefore, the reaction does notfit that of a second-order model.

A similar approach was used for the reaction between DG and methanol as shown inEquations (10)–(12):

−∫ DG

DG0

d(DG)

(DG)= kDG

∫ t

0dt, (10)

ln(DG0)

(DG)= kDGt, (11)

kDG = 1

tln

(DG0)

(DG), (12)

where kDG, DG and DG0 denote the rate constant for DG, the concentration of DG and the initialconcentration of DG. Figure 4 shows that a plot of ln (DG0/DG) versus reaction time (t) is astraight line, thus the reaction involving DG follows the first-order model. The rate constants forDG are given in Table 2.

The rate of a reaction is very sensitive to change in temperature. Thus, it is very importantthat the kinetics study should be conducted in a vessel kept in a thermostatically controlledbath. Noureddini and Zhu (1997) reported that the rate of a reaction almost always increases withtemperature for an elementary irreversible reaction. However, for multiple and reversible reactions,the rate constants do occasionally exhibit an optimal temperature with respect to the yield of adesired product. The rate constants for the first two reactions increase with temperature for theforward reactions. Thus, indirectly, these findings prove that our assumption of an irreversiblereaction is valid since the rate increases with temperatures (Tables 1 and 2). The kinetics studyfor the reaction involving MG could not be performed because it occurred so fast that MG couldnot be detected on the GC chromatogram.

Figure 4. First-order kinetics model for the transesterification of J. curcas DG with methanol at various temperatures.

Table 2. Rate constant, kDG, for the reaction betweenmethanol and DG of J. curcas.

Temperature (◦C) kDG (first order) (min−1) R2

50 0.07 0.9955 0.13 0.9960 0.18 0.9865 0.20 0.99

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Figure 5. Arrhenius plot showing the temperature dependency of the reaction rate constants.

3.4. Determination of activation energy, E±

It has been reported that the rate constant for any reaction depends on two factors (Avery 1974),namely the frequency of collisions between the reactant molecules and the value of the activationenergy. The dependency of the rate constant, k, on temperature follows the Arrhenius equation:

k = A exp(−Ea/RT). (13)

Equation (13) was then substituted into the logarithmic form as shown in Equation (14):

log10 k = (−Ea/2.303RT) + log10 A, (14)

where T is expressed in K and R is the universal gas constant. The activation energy (Ea) wasestimated from the slope of a plot of log10 k versus 1/T . In these equations, k refers to eitherkTG or kDG. The frequency factor, A, was determined from the y-intercept. The plot is shown inFigure 5 for the synthesis of J. curcas methyl ester at 50–65 ◦C. These data were used to determinethe Arrhenius energy of activation.

The activation energies for the transesterification of JCT and DG with methanol are 27.38and 46.72 kJ mol−1, respectively. The values are lower than those reported by Jain and Sharma(2010), who conducted the synthesis of biodiesel fuels from Jatropha oil using sodium hydroxide.The reported activation energy was 87.80 kJ mol−1. In this study, the transesterification of JCTtook place at a much higher rate than in the previous work and hence the activation energy waslower. When the energy barrier is low, the reaction will be fast as the thermal energy of thereactants will be sufficient to overcome the barrier to move over to the products. Nonetheless,the transesterification of TG from palm oil reported by Darnoko and Cheryan (2000) resulted ina slightly lower Ea (26.80 kJ mol−1) than that of the TG from JCT (27.38 kJ mol−1) due to thefatty acid composition of the palm oil, which contains equal fractions of saturated and unsaturatedcompounds (Maycock 1987). JCT contains about 80% unsaturated compounds and thus a higheractivation energy is needed to break the double bond of the tetrahedral intermediate. Accordingto Noureddini and Zhu (1997), for multiple reactions, a high temperature favours the reaction ofhigher activation energy, and a low temperature favours the reaction of lower activation energy. Todate, there have been no many published reports on the kinetics of transesterification of vegetableoils to form biodiesel. The only reports of Ea values for k1, k2 and k3 are for the transesterificationreactions of vegetable oil with methanol to form methyl ester (Freedman et al. 1986, Joelianingsih2008, Noureddini & Zhu 1997). However, the reports published different values of kinetics datadue to variations in the reaction parameters and feedstocks.

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4. Conclusion

The kinetics of the transesterification of JCT and methanol to J. curcas methyl ester were examined.The mechanism of the reaction was postulated to occur via three stepwise irreversible elementaryreactions involving TG, DG and MG to form intermediates and the final product, methyl ester.However, the rate of the reaction involving MG was too fast, thus the step was not considered asrate controlling. In addition, the conversion of TG and DG into methyl ester appeared to followa first-order model up to 60 min of the reaction time. The rate constants for the formation ofintermediate DG and TG were determined at various temperatures. The values of kTG rangedfrom 0.11 to 0.17 min−1 and the values of kDG ranged from 0.07 to 0.20 min−1. The activationenergies for the stepwise reaction in the transesterification of JCT and DG with methanol were27.38 and 46.72 kJ mol−1, respectively. This study has demonstrated that the transesterificationof J. curcas oil (JCO) can be conducted under a shorter reaction time. This is mainly due to thelower activation energies. When the energy barrier is low, the reaction is faster as the thermalenergy of the reactants will be sufficient to surmount the barrier to move over to the products.

Acknowledgement

These experimental works were carried out under the financial support of Fundamental Research Grant Scheme (FRGS)from Higher Education Ministry, Malaysia.

References

Avery, H.E., 1974. Basic reaction kinetics and mechanism. London: Macmillan.Baig, A. and Ng, F.T.T., 2010. A single-step solid acid-catalyzed process for the production of biodiesel from high free

fatty acid feedstocks. Energy Fuels, 24, 4712–4720.Darnoko, D. and Cheryan, M., 2000. Kinetics of palm oil transesterification in a batch reactor. Journal of American Oil

Chemists Society, 77 (12), 1263–1267.Diasakou, M., Louloudi, A., and Papayannakos, N., 1998. Kinetics of the non-catalytic transesterification of soybean oil.

Fuel, 77, 1297–1302.Freedman, B., Pryde, E.H., and Mounts, T.L., 1984. Variables affecting the yields of fatty ester from transesterified

vegetable oils. Journal of American Oil Chemists Society, 61, 1638–1643.Freedman, B., Butterfield, R.O., and Pryde, E.H., 1986. Transesterification kinetics of soybean oil. Journal of American

Oil Chemists Society, 63 (10), 1375–1380.Jain, S. and Sharma, M.P., 2010. Kinetics of acid base catalyzed transesterification of Jatropha curcas oil. Bioresource

Technology, 101, 7701–7706.Joelianingsih, et al., 2008. Biodiesel fuels from palm oil via the non-catalytic transesterification in a bubble column reactor

at atmospheric pressure: a kinetics study. Renewable Energy, 33, 1629–1636.Komers, K., et al., 2002. Kinetics and mechanism of the KOH-catalyzed methanolysis of rapeseed oil for biodiesel

production. European Journal of Lipid Science and Technology, 104 (11), 728–737.Kusdiana, D. and Saka, S., 2001. Kinetics of transesterification in rapeseed oil to biodiesel fuel as treated in supercritical

methanol. Fuel, 80, 693–698.Liu, K., 1994. Preparation of fatty acid methyl ester for gas-chromatographic analysis of lipids in biological materials.

Journal of American Oil Chemists Society, 71 (11), 1179–1187.Lin, S.W., Sue, T.T., and Ai, T.Y., 1995. PORIM test methods. Malaysia: Palm Oil Research Institute of Malaysia.Maycock, J.H., 1987. Extraction of crude palm oil. In: F.D. Gunstone, ed. Critical reports on applied chemistry. New

York: John Wiley & Sons, 29–38.Noureddini, H. and Zhu, D., 1997. Kinetics of transesterification of soybean oil. Journal of American Oil Chemists Society,

74 (11), 1457–1463.Openshaw, K., 2000. A review of Jatropha curcas: an oil plant of unfulfilled promise. Biomass & Bioenergy, 19, 1–15.Rashid, U., et al., 2011. Muskmelon (Cucumis melo) seed oil: a potential non-food oil source for biodiesel production.

Energy, 36 (9), 5632–5639.Tanguy, F.D., Marie-Françoise, R., and Guy, B.M., 2006. Kinetics of heterogeneously MgO-catalyzed transesterification.

Applied Catalyst B: Environmental, 61, 35–45.Tapanes, N.O., et al., 2008. Transesterification of Jatropha curcas oil glycerides: theoretical and experimental studies of

biodiesel reaction. Fuel, 87, 2286–2295.Vicente, G., Martinez, M., and Aracil, J., 2006. Kinetics of Brassica carinata oil methanolysis. Energy and Fuel, 20 (4),

1722–1726.Yunus, R., et al., 2002. A simple capillary column gas chromatography method for analysis of palm oil-based polyol ester.

Journal of American Oil Chemists Society, 79, 1075–1080.

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