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Biodiesel preparation from Phoenix tree seed oil using ethanol as acyl acceptor
Industrial Crops & Products 137 (2019) 270–275
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Biodiesel preparation from Phoenix tree seed oil using ethanol as acyl acceptor
T
⁎
Shangde Suna,b, , Jingjing Guoa,b, Xu Duanc a Lipid Technology and Engineering, School of Food Science and Engineering, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China b Provincal Key Laboratory for Transformation and Utilization of Cereal Resource, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China c Food and Biology Engineering College, Henan University of Science and Technology, No. 263, Kaiyuan road, Luoyang, Henan Province, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Fatty acid ethyl ester Phoenix tree seed oil Ethanol Biodiesel Transesterfication Response surface methodology
Fatty acid ethyl ester (FAEE) is one kind of renewable biodiesel, which has lower emissions of mono-nitrogen oxides, lower smoke opacity, higher energy contents, lower pour, and cloud points. In this work, phoenix (Firmiana simplex L.) tree seed oil (PTSO) from Sterculiaceae was used as the novel feedstock to produce FAEE. Ethanol was used as fatty acyl acceptor and sodium hydroxide was employed as a catalyst. Response surface methodology was used to evaluate and optimize the effect of transesterification variables on FAEE yield. The effect of reaction variables on the transesterification was as follows: catalyst concentration > transesterification temperature > substrate ratio. Transesterfication variables were optimized as follows: 0.3% catalyst concentration with 10.8:1 substrate ratio (ethanol to PTSO, mol/mol) at 52.7 °C for 20 min. Under these optimized transesterification variables, the maximum FAEE yield (97.4 ± 1.7%) was obtained. These can provide an efficient and effective information for biodiesel preparation using PTSO as the novel feedstock.
1. Introduction With the depletion of non-renewable energy and the aggravation of environmental pollution, it is interesting of developing the economical and environment-friendly fuel alternatives for petroleum energy (Chang et al., 2013). Recently, biodiesel has been developed as a good alternative for diesel, which was attributed to the lower exhaust emissions, innocuous, renewable, and sulfur free (de Lima et al., 2016; Demirbas, 2005; Rintoul, 2010; Vyas et al., 2010). The main component of biodiesel is fatty acid alkyl ester, which can be prepared by the transesterfication of vegetable oil with short-chain alcohols (methanol or ethanol) (Cervero et al., 2014). Compared with methanol, ethanol is also a good fatty acyl acceptor for biodiesel production because ethanol is a renewable and environmentally friendly material (Demirbas, 2003; Kumar et al., 2010; Li et al., 2013; Stamenkovic et al., 2011; Verma and Sharma, 2016). Meanwhile, fatty acid ethyl ester (FAEE) has many advantages as renewable biodiesel, for example, lower emissions of mono-nitrogen oxides, lower smoke opacity, higher energy contents, lower pour, and cloud points (Rottig et al., 2010; Stamenkovic et al., 2011). In addition, FAEE can also be used as flavor compounds and
drugs in the pharmaceutical, food, and chemical industries (Bolonio et al., 2019; Campos-Garcia et al., 2018; Lapointe et al., 2019; Ndiaye et al., 2005). Therefore, FAEE preparation has been an important and interesting field. At present, more than 95% raw material of biodiesel production are edible oils, such as, corn (Zea mays L.) oil, soybean (Glycine max L.) oil, and other vegetable oils, which results in the imbalance between energy use with food consumption (Atapour and Kariminia, 2011; Goering et al., 1982). Therefore, the development of some new oil resources, such as, rubber (Hevea brasiliensis L.) seed oil, manketti (Ricinodendron rautanenii Schinz) oil, baobab (Adansonia digitata L.) oil, date palm (Phoenix dactylifera L.) oil, jatropha (Jatropha curcas L.) seed oil, manchurian apricot (Prunus mandshurica Skv.) oil, siberian apricot (Prunus sibirica L.) oil, and Chicha (Acanthopanax senticosus (Rupr. Et Maxim.) Harms) oil, as feedstock for biodiesel preparation, have attracted more attention (Amani et al., 2013; Demirbas, 2017; Farooq et al., 2018; Gomes Filho et al., 2015; Kamel et al., 2018; Khazaai et al., 2017; Modiba et al., 2014; Rutto and Enweremadu, 2011; Wang, 2013). Compared with date palm seed of the palm family in Middle Eastern and North African countries (Al-Muhtaseb et al., 2016, 2017; Jamil
⁎ Corresponding author at: Lipid Technology and Engineering, School of Food Science and Engineering, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China. E-mail addresses: [email protected] (S. Sun), [email protected] (J. Guo), [email protected] (X. Duan).
https://doi.org/10.1016/j.indcrop.2019.05.035 Received 9 January 2019; Received in revised form 11 May 2019; Accepted 13 May 2019 Available online 20 May 2019 0926-6690/ © 2019 Elsevier B.V. All rights reserved.
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Fig. 1. Transesterfication of phoenix tree seed oil (PTSO) with ethanol using NaOH catalyst to prepare fatty acid ethyl esters (FAEE).
et al., 2018), phoenix tree seed (PTS) is the novel resource from phoenix tree (Firmiana simplex L., a family of Sterculiaceae), which is a deciduous, medicinal, and ornamental plant in China, Korea, Europe, Japan, and USA (Woo et al., 2016; Li et al., 2009). And PTS has been used as the folk medicine to treat stomach disorders and diarrhea. The oil content of PTS is ˜30%, which is higher than that of date palm seed from date palm (10%), soybean (˜15%), corn (˜5%), and cottonseed (Gossypium spp.) (˜20%) (Anwar et al., 2013; Conway and Earle, 1963; Fadhil et al., 2017; Garca-Ayuso et al., 2000). The main fatty acids of the oil from PTS are linoleic acid (30.2%), oleic acid (22.2%), and palm acid (17.4%) (Sun and Li, 2016), which are different from those of date palm seed oil (lauric acid 11.36%, myristic acid 11.44%, palmitic acid 13.84%, stearic acid 6.56%, and oleic acid 51.45%) (Fadhil et al., 2017). Therefore, compared with these resources, PST was a novel resource for biodiesel preparation. In this work, phoenix tree seed oil (PTSO) was used as the new feedstock and ethanol was used as fatty acyl acceptor for FAEE preparation (Fig. 1). Sodium hydroxide is employed as a catalyst to catalyze the transesterification of PTSO with ethanol. The effects of reaction variables, such as NaOH concentration, reaction temperature, substrate ratio, and reaction time on FAEE yield were investigated. Response surface methodology (RSM) was used to evaluate and optimize the effect of the interactions of these reaction variables on FAEE yield.
catalyst (NaOH dissolved in amount of ethanol) was added to reaction mixture. The samples were taken out at set intervals and dissolved in 3 mL n-hexane, and then dried using anhydrous sodium sulfate, and followed by centrifugation. Finally, the supernatant liquid was collected and filtered using a microfilter (0.45 mm) for high temperature gas chromatography (GC) analysis.
2. Materials and methods
For evaluating the interaction effect of transesterification variables on FAEE yield, a 3-level-3-factor Box-Behnken design was used. In the RSM design, the factors and levels were molar ratio of ethanol to PTSO (5:1, 10:1 and 15:1 mol/mol), reaction temperature (30 °C, 50 °C and 70 °C), and catalyst concentration (0.1%, 0.3% and 0.5%; relative to the weight of all substrates).
2.4. Analysis methods According to the IUPAC methods, the acid value of PTSO was analyzed (Paquot and Hauntfenne, 1987). FAEE yield was determined by high temperature GC. For evaluating FAEE yield, high temperature GC (Agilent 7980B) with a flame ionization detector and DB-1H capillary column (30m × 0.25 mm, 0.1 μm of film thickness) was employed to analyze samples. High temperature GC conditions were as follows: the initial column temperature was 100 °C, and increased to 220 °C at 50 °C/min, then to 290 °C at 15 °C/min, and then increased to 320 °C at 40 °C/min, and at 320 °C for 8 min, finally to 360 °C at 20 °C/min, and at 360 °C for 6 min. The injector and detector temperatures were 350 °C and 400 °C, respectively. Carrier gas was helium at 1 mL/min. 2.5. Experimental design
2.1. Materials Phoenix tree seed (PTS) was provided by Jiangsu Xintai Wholesale Seed Industry Co. Ltd. (Jiangsu, China). N-hexane (chromatograph grade) was provided from Tianjin Guangfu Technology Development Co. Ltd. (Tianjin, China). Ethanol and sodium hydroxide were purchased from Tianjin Kemiou Chemical Reagent Co. Ltd. (Tianjin, China).
2.6. Statistical analysis The experimental data was analyzed by Design-Expert 8.0 and can be generalized by second-order polynomial model as follows:
2.2. Extraction of PTSO
3
Y = β0 +
Before the extraction, the impurities and excess moisture were removed from PTS. In order to obtain seed powder, the seeds were dried and crushed using a pulverizer, and then passed by a 40 mesh sieve. Next, petroleum ether was as the solvent to extract the oil from Phoenix tree seed powder. Finally, the solvent of supernatant was removed using a rotary evaporator. The oil obtained was used as feedstock for biodiesel preparation.
3
2
3
∑ βi Xi + ∑ βii Xi2 + ∑ ∑ i= 1
i=1
βij Xi XJ
i=1 j=i+1
(1)
Where Y is the predicted FAEE yield; Xi and Xj represent the transesterification variables. Regression coefficients β0, βi, βii, and βij are the intercept, linear, quadratic, and interaction terms, respectively. 3. Results and discussion
2.3. Transesterification of PTSO with ethanol
3.1. Effect of catalyst concentration on FAEE preparation
The mixture of PTSO with ethanol was mixed at 200 rpm and different temperatures (25–70 °C). The reaction was initiated when the
Sodium hydroxide (NaOH) has been widely used as catalyst for many reactions due to the cheap price and high activity (Saydut et al., 271
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Fig. 3. Effect of reaction temperature on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 0.4% catalyst concentration (relative on the weight of all substrates), 10:1 molar ratio of ethanol to PTSO (phoenix tree seed oil) and 200 rpm.
Fig. 2. Effect of catalyst concentration on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 10:1 molar ratio of ethanol to PTSO (phoenix tree seed oil), 200 rpm and 30 °C.
2010). However, the amount of free fatty acids (FFA) has an important influence on the activity of NaOH. Normally, low FFA content (< 2%) is necessary for NaOH-catalyzed reactions (Dorado et al., 2002; Rodriguez-Guerrero et al., 2013). In this work, the FFA content of PTSO was 0.46%, which suggested that NaOH can be used as the catalyst for the trasesterification of PTSO. A significant effect of NaOH concentration on the transesterification of PTSO with ethanol was found from Fig. 2. For evaluating the influence of NaOH concentration on FAEE yield, different NaOH concentrations from 0.05% (relative on the weight of all substrates) to 0.4% were used. In order to improve the activity of NaOH, before the reaction started, NaOH was firstly dissolved in ethanol to form alkoxide group, which can attack on the carbonyl carbon atom of the triglyceride to form a tetrahedral intermediate and result in a novel fatty acid ester and a diglyceride by the rearrangement of the tetrahedral intermediate (Saydut et al., 2010; Encinar et al., 2007; da Silva et al., 2009). Although small water was formed by the reaction between NaOH with ethanol, there was no significant effect on FAEE yield. Fig. 2 shows that the maximum FAEE yield was obtained after 20–30 min. Very low FAEE yield (< 5%) was obtained when low NaOH concentrations (0.05% and 0.1%) was used, which was due to the neutralization of the present FFA (0.46%) in PTSO for NaOH. After that, with the increase of NaOH concentration from 0.1% to 0.3%, FAEE yield increased rapidly from 2.5 ± 0.6% to 86.1 ± 1.4% (Fig. 2). When NaOH concentrations were higher than 0.3%, the transesterification reached equilibrium at 20 min and the maximum FAEE yield (˜84%) can also be obtained after 20 min. However, during the transesterification, the higher NaOH concentration, the more soap formed, which could intensify the emulsification of reaction system and made the separation of FAEE from product very difficult (Encinar et al., 2005; Atapour et al., 2014). Fig. 2 also shows that 0.3% NaOH concentration is enough for converting PTSO to FAEE by the transesterification, which is lower than that of manketti oil (1.02%), threated rubber seed oil (0.5%), and yellow sarson (Brassica campestris L.) oil (1%). These was ascribed to the fact that, compared with manketti oil (6% FFA content), threated rubber seed oil (2% FFA content), and yellow sarson oil (0.6% FFA content) (Rutto and Enweremadu, 2011; Ramadhas et al., 2005; Nosheen et al., 2013), the FFA content of PTSO (0.46%) was very low.
temperatures (25–70 °C) were used in the experiments (Fig. 3). With the increase of reaction temperature from 25 °C to 40 °C, FAEE yield increased from 82.8 ± 1.6% to 92.3 ± 0.9% at 20 min, and the time to achieve equilibrium shortened from 40 min to 20 min, which was due to the decrease of the effect of the viscosity of reaction system and mass transfer limitation. In general, temperature nearer to the boiling point of alcohol was optimum for the transesterification (Ma and Hanna, 1998). However, at high temperature, the side reaction to form soap by the saponification of triglycerides with NaOH was faster than the transesterification. Similar saponification reaction can be found in other reaction (Atapour and Kariminia, 2011). With the increase of temperature from 40 °C to 70 °C, FAEE yield increased only ˜5% at 20 min. Above all, 40 °C is the best reaction temperature for FAEE preparation, which was lower than the optimal reaction temperature of frying oil (78 °C), soybean oil (70 °C), and yellow sarson oil (75 °C) (Encinar et al., 2007; Nosheen et al., 2013; Tippayawong et al., 2005). 3.3. Effect of molar ratio of ethanol to PTSO Fig. 4 shows that the increase of substrate ratio has a great effect on FAEE formation. With the increase of substrate ratio from 3:1 to 15:1, a rapid increase of FAEE yield from 68.7 ± 1.2% to 99.3 ± 0.9% was found at 20 min. These results were ascribed to the fact that excess amount of ethanol will increase FAEE conversion by shifting reaction
3.2. Effect of transesterification temperature Reaction temperature can not only accelerate the reaction, but also reduce the effect of mass transfer limitation. However, high temperature also resulted in the evaporation of solvent. In order to evaluate the influence of temperature on the transesterification of PTSO, different
Fig. 4. Effect of molar ratio of ethanol to PTSO (phoenix tree seed oil) on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 0.4% catalyst concentration (relative to the weight of substrates), 60 °C and 200 rpm. 272
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e2.52X2X3 e42.43X12 e3.93X22 e5.73X32
Table 1 Box–Behnken design and results of FAEE yield as affected by molar ratio of substrates, reaction temperature, and catalyst concentration. Trial
X1 (%) Catalyst concentration
X2 (°C) Reaction temperature
X3 (mol/mol, ethanol to PTSO)
FAEE yield (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
0.1(-1) 0.1(-1) 0.3(0) 0.3(0) 0.5(1) 0.5(1) 0.3(0) 0.3(0) 0.3(0) 0.5(1) 0.3(0) 0.3(0) 0.3(0) 0.3(0) 0.5(1) 0.1(-1) 0.1(-1)
50(0) 50(0) 50(0) 50(0) 50(0) 50(0) 70(1) 30(-1) 50(0) 30(-1) 50(0) 30(-1) 50(0) 70(1) 70(1) 30(-1) 70(1)
5(-1) 15(1) 10(0) 10(0) 5(-1) 15(1) 15(1) 5(-1) 10(0) 10(0) 10(0) 15(1) 10(0) 5(-1) 10(0) 10(0) 10(0)
1.1 ± 0.3 1.4 ± 0.2 92.7 ± 2.1 92.3 ± 1.8 79.4 ± 1.2 95.0 ± 1.4 95.5 ± 2.4 64.9 ± 1.8 92.5 ± 1.5 89.2 ± 1.6 92.5 ± 1.3 89.7 ± 0.4 92.2 ± 1.2 80.8 ± 1.5 92.5 ± 0.6 1.1 ± 0.2 1.3 ± 0.4
(2)
Fig. 5A shows the influence of reaction temperature, NaOH concentration, and their mutual interaction on FAEE yield with 10:1 substrate ratio of ethanol to PTSO. Raising temperature and substrate ratio were beneficial for FAEE formation. When the moderate NaOH concentration (0.3–0.4%) and temperature (38–54 °C) were used, the high FAEE yields (> 92.2%) were obtained. Fig. 5B shows the changes of FAEE yield with varying substrate ratio and NaOH concentration. When substrate ratio was 9:1 (mol/mol), FAEE yield rapidly increased with the increase of NaOH concentration from 0.1% to 0.4%. The higher FAEE yields (> 98.8%) were obtained with lower substrate ratio (7:1–11:1 mol/mol) and higher NaOH concentration (0.3–0.4%). Fig. 5C shows the relationship of varying substrate ratio and transesterification temperature on FAEE yield with 0.3% NaOH concentration. The FAEE yield increased with the increase of substrate ratio from 5:1 to 15:1 (mol/mol). However, a further increasing of substrate ratio (> 15:1 mol/mol) would lead to a decline of FAEE yield. The higher FAEE yield (> 90.9%) appeared at moderate reaction temperature (46–54 °C) and higher substrate ratio (9:1–13:1 mol/mol).
3.5. Optimum transesterification conditions and model verification
equilibrium to the formation of FAEE (Shimada et al., 2002). With further increase of substrate ratio (≥15:1), only little improvement on FAEE yield (˜99.4%) was obtained at 20 min. Excess amount of ethanol can also increase the solubility of glycerol and result in a decrease in FAEE yield (Murugesan et al., 2009; Fillieres et al., 1995). Therefore, 15:1 substrate ratio was the best choice for the reaction, which was similar with that of castor (Ricinus communis L.) oil (16:1) (da Silva et al., 2009).
In order to verify the adequacy of the optimal reaction variables and the predicted models, experiments were carried out under the optimized conditions. Transesterification conditions were optimized as follows: transesterification temperature 52.7 °C, catalyst concentration 0.3%, reaction time 20 min and 10.8:1 substrate ratio. Under these optimal variables, the maximum FAEE yield (97.4 ± 1.7%) was achieved and it was well accorded with the predicted FAEE yield (98.9%), which indicated the validation of the model. The optimal NaOH concentration (0.3%) was lower than that of Leung and Guo (1.1% NaOH concentration) (2006) used frying oil with 94.0% FAEE yield, which was ascribed to the higher FFA content (1.1%) in the frying oil. The best temperature for FAEE preparation using PTSO was 52.7 °C, which was lower than that of Encinar et al. (2005) (78 °C, 1% KOH concentration) and Tippayawong et al. (2005) (70 °C, 1.0% KOH concentration) with only ˜93% FAEE yield using frying oil and soybean oil, respectively. Compared with the previous reports for FAEE preparation, 97.4 ± 1.7% FAEE yield can be achieved in 20 min, which was very faster than that of the previous methods for biodiesel preparation (3 h for CaO as catalyst and soybean oil as raw material (Liu et al., 2008), 1 h for sodium methoxide as catalyst and baobab oil as raw material (Modiba et al., 2014)). The work can provide an efficient method for biodiesel preparation using PTSO as raw material.
3.4. Response surface analysis and model fitting In the analysis of multifactor quantitative experiment, RSM was employed to analyze the regression relationship between dependent and independent variables, which is used to optimize experimental variables (Syam et al., 2016). Table 1 shows the experimental results obtained from the model. The data were regressed by employing a quadratic polynomial equation, which was used to evaluate the mutual relationship between FAEE yield and transesterification variables. Table 2 shows the ANOVA analysis for the model. Due to the low Pvalue (P < 0.001), the model was adequate to explain the mutual relationship between reaction variables with FAEE yield. The effect of transesterification variables on FAEE yield decreased in the order of NaOH concentration > substrate ratio > transesterification temperature. Regression equation explaining FAEE yield was given as follow: Y (%)=92.38+43.90X1 e3.15X2 + 6.93X3 + 0.77X1X2 + 3.83X1X3 Table 2 Analysis of variance (ANOVA) for quadratic model to FAEE yield. Sourse
Sum of squares
Degrees of freedom
Mean square
F value
Prob > F
Model X1 X2 X3 X1 X2 X1 X3 X2 X3 X12 X22 X32 Residual Lack of fit Total R2 = 0.9951
23998.68 15417.68 79.38 383.65 2.40 58.52 25.50 7579.34 64.95 138.12 118.06 117.87 24116.74
9 1 1 1 1 1 1 1 1 1 7 3 16 RAdj2 = 0.9888
2666.52 15417.68 79.38 383.65 2.40 58.52 25.50 7579.34 64.95 138.12 16.87 39.29
158.11 914.16 4.17 22.75 0.14 3.47 1.51 449.40 3.83 8.19
< 0.0001 < 0.0001 0.0667 0.0020 0.7170 0.1048 0.2585 < 0.0001 0.0905 0.0243
835.96
< 0.0001
273
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Fig. 5. (A) 3D surface plots between reaction temperature with NaOH concentration for FAEE (fatty acid ethyl esters) yield with 10:1 substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)).Fig. (B) 3D surface plots between substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)) with NaOH concentration for FAEE (fatty acid ethyl esters) yield at 50 °C. Fig. (C) 3D surface plots between reaction temperature with substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)) for FAEE (fatty acid ethyl esters) yield with 0.3% NaOH concentration (relative to the total weight of substrates).
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4. Conclusions
a potential new feedstock for liquid bio-fuels production. Fuel 210, 165–176. Farooq, M., Ramli, A., Naeem, A., Mahmood, T., Ahmad, S., Humayun, M., Islam, M.G.U., 2018. Biodiesel production from date seed oil (Phoenix dactylifera L.) via egg shell derived heterogeneous catalyst. Chem. Eng. Res. Des. 132, 644–651. Fillieres, R., Benjelloun-Mlayeh, B., Delmas, M., 1995. Ethanolysis of rapeseed oil: quantitation of ethyl esters, mono-, di- and triglycerides and glycerol by high-performance size-exclusion chromatography. J. Am. Oil Chem. Soc. 72, 427–432. Garca-Ayuso, L.E., Velasco, J., Dobarganes, M.C., Luque de Castro, M.D., 2000. Determination of the oil content of seeds by focused microwave-assisted soxhlet extraction. Chromatographia 52, 103–108. Goering, C.E., Schwab, A.W., Daugherty, M.J., Pryde, E.H., Heakin, A.J., 1982. Fuel properties of eleven vegetable oils. Appl. Eng. Agric. 25, 1472–1483. Gomes Filho, J.C., Peiter, A.S., Pimentel, W.R.O., Soletti, J.I., Carvalho, S.H.V., Meili, L., 2015. Biodiesel production from Sterculia striata oil by ethyl transesterification method. Ind. Crop. Prod. 74, 767–772. Jamil, F., Al-Muhatseb, A., Myint, M.T.Z., Al-Hinai, M., Al-Haj, L., Baawain, M., Al-Abri, M., Kumar, G., Atabani, A.E., 2018. Biodiesel production by valorizing waste Phoenix dactylifera L. Kernel oil in the presence of synthesized heterogeneous metallic oxide catalyst (Mn@MgO-ZrO2). Energ. Convers. Manage. 155, 128–137. Kamel, D.A., Farag, H.A., Amin, N.K., Zatout, A.A., Ali, R.M., 2018. Smart utilization of jatropha (Jatropha curcas Linnaeus) seeds for biodiesel production: optimization and mechanism. Ind. Crop. Prod. 111, 407–413. Kumar, D., Kumar, G., Singh, P.C.P., 2010. Fast, easy ethanolysis of coconut oil for biodiesel production assisted by ultrasonication. Ultrason. Sonochem. 17, 555–559. Lapointe, J., BPharm, H.L., Aziz, S., Jordan, H., Hegele, R.A., Lemieux, P., 2019. A singledose, comparative bioavailability study of a formulation containing OM3 as phospholipid and free fatty acid to an ethyl ester formulation in the fasting and fed states. Clin. Ther. 41, 426–444. Li, Z.Z., Tang, X.W., Chen, Y.M., Wei, L.M., Wang, Y., 2009. Activation of Firmiana simplex leaf and the enhanced Pb (II) adsorption performance: equilibrium and kinetic studies. J. Hazard. Mater. 169, 386–394. Li, Q., Xu, J., Du, W., Li, Y., Liu, D., 2013. Ethanol as the acyl acceptor for biodiesel production. Renew. Sust. Energ. Rev. 25, 742–748. Liu, X.J., He, H.Y., Wang, Y.J., Zhu, S.L., Piao, X.L., 2008. Transesterification of soybean oil to biodiesel using CaO as a solid base catalyst. Fuel 87, 216–221. Ma, F., Hanna, M.A., 1998. The effects of catalyst, free fatty acids and water on transesterification of beef tallow. Ind. Eng. Chem. Res. 41, 1261–1264. Modiba, E., Osifo, P., Rutto, H., 2014. Biodiesel production from baobab (Adansonia digitata L.) seed kernel oil and its fuel properties. Ind. Crop. Prod. 59, 50–54. Murugesan, A., Umarani, C., Chinnusamy, T.R., Krishnan, M., Subramanian, R., Neduzchezhain, N., 2009. Production and analysis of bio-diesel from non-edible oilsa review. Renew. Sust. Energ. Rev. 13, 825–834. Ndiaye, P.M., Tavares, F.W., Dalmolin, I., Dariva, C., Oliveira, D., Oliveira, J.V., 2005. Vapor pressure data of soybean oil, castor oil, and their fatty acid ethyl ester derivative. J. Chem. Eng. Data 50, 330–333. Nosheen, A., Bano, A., Ullah, F., 2013. The optimization of biodiesel production from yellow sarson (Brassica campestris L.) oil. Energy Sources Part A-Recovery Util. Environ. Eff. 35, 278–281. Paquot, C., Hauntfenne, A., 1987. IUPAC Standard Methods for the Analysis of Oils, Fats and Derivatives. Blackwell, London. Ramadhas, A.S., Jayaraj, S., Muraleedharan, C., 2005. Biodiesel production from high FFA rubber seed oil. Fuel 84, 335–340. Rintoul, S., 2010. Biofuels blend measurements with portable mid-infrared analyzers. INFORM-International News on Fats, Oils and Related Materials. 21 (8), 521–522. Rodriguez-Guerrero, J.K., Rubens, M.F., Rosa, P.T.V., 2013. Production of biodiesel from castor oil using sub and supercritical ethanol: effect of sodium hydroxide on the ethyl ester production. J. Supercrit. Fluid. 83, 124–132. Rottig, A., Wenning, L., Broker, D., Steinbuchel, A., 2010. Fatty acid alkyl esters: perspectives for production of alternative biofuels. Appl. Microbiol. Biot. 85, 1713–1733. Rutto, H.L., Enweremadu, C.C., 2011. Optimization of production variables of biodiesel from Manketti using response surface methodology. Int. J. Green Energy 8, 768–779. Saydut, A., Kafadar, A.B., Tonbul, Y., Kaya, C., Aydin, F., Hamamci, C., 2010. Comparison of the biodiesel quality produced from refined sunflower (Helianthus annuus L.) oil and waste cooking oil. Energ. Explor. Exploit. 28, 499–512. Shimada, Y.J., Watanabe, Y.M., Sugihara, A.K., Tominaga, Y., 2002. Enzymatic alcoholysis for biodiesel fuel production and application of the reaction to oil processing. J. Mol. Catal. B-Enzym. 17, 133–142. Stamenkovic, O.S., Velickovic, A.V., Veljkovic, V.B., 2011. The production of biodiesel from vegetable oils by ethanolysis: current state and perspectives. Fuel 11, 3141–3155. Sun, S.D., Li, X.L., 2016. Physicochemical properties and fatty acid profile of Phoenix tree Seed and its oil. J. Am. Oil Chem. Soc. 93, 1111–1114. Syam, A.M., Rashid, U., Yunus, R., Hamid, H.A., Al-Resayes, S.I., Nehdi, I.A., AlMuhtaseb, A.H., 2016. Conversion of Oleum papaveris seminis oil into methyl esters via esterification process: optimization and kinetic study. Grasas Aceites 67, 1–9. Tippayawong, N., Kongjareon, E., Jompakdee, W., 2005. Ethanolysis of soybean oil into biodiesel: process optimization via central composite design. J. Mech. Sci. Technol. 19, 1902–1909. Verma, P., Sharma, M.P., 2016. Comparative analysis of effect of methanol and ethanol on Karanja biodiesel production and its optimization. Fuel 180, 164–174. Vyas, A.P., Verma, J.L., Subrahmanyam, N., 2010. A review on FAME production processes. Fuel 89, 1–9. Wang, L.B., 2013. Properties of Manchurian apricot (Prunus mandshurica Skv.) and Siberian apricot (Prunus sibirica L.) seed kernel oils and evaluation as biodiesel feedstocks. Ind. Crop. Prod. 50, 838–843. Woo, K.W., Suh, W.S., Subedi, L., Kim, S.Y., Kim, A., Lee, K.R., 2016. Bioactive lignan derivatives from the stems of Firmiana simplex. Bioorg. Med. Chem. Lett. 26, 730–733.
In this work, biodiesel can be successfully prepared using PTSO as the new material and ethanol as fatty acyl acceptor. NaOH was used to catalyze the transesterification of PTSO with ethanol. The effect of transesterification conditions on FAEE yield was evaluated and optimized using RSM. The maximum FAEE yield (97.4 ± 1.7%) from PTSO can be obtained under the optimal conditions as follows: transesterification temperature 52.7 °C, catalyst concentration 0.3%, reaction time 20 min and 10.8:1 substrate ratio. And the influence of transesterification conditions on the reaction decreased in the order of NaOH concentration > substrate ratio > transesterification temperature. A quadratic regression model between reaction conditions with FAEE yield was also achieved from RSM. Acknowledgements The authors gratefully acknowledge financial support from National Natural Science Foundation of China (31771937) and Provincal Key Laboratory for Transformation and Utilization of Cereal Resource (PL2016008). The authors thank Jianxing Sun and Meng Wang for their help with the experiments on FAEE yield determination. References Al-Muhtaseb, A.H., Jamil, F., Al-Haj, L., Al-Hinai, M.A., Baawain, M., Myint, M.T.Z., Rooney, D., 2016. Efficient utilization of waste date pits for the synthesis of green diesel and jet fuel fractions. Energ. Convers. Manage. 127, 226–232. Al-Muhtaseb, A.H., Jamil, F., Myint, M.T.Z., Baawain, M., Al-Abri, M., Dung, T.N.B., Kumar, G., Ahmad, M.N.M., 2017. Cleaner fuel production from waste Phoenix dactylifera L. Kernel oil in the presence of a bimetallic catalyst: optimization and kinetics study. Energ. Convers. Manage. 146, 195–204. Amani, M.A., Davoudi, M.S., Tahvildari, K., Nabavi, S.M., Davoudi, M.S., 2013. Biodiesel production from Phoenix dactylifera as a new feedstock. Ind. Crop. Prod. 43, 40–43. Anwar, F., Yaqoub, A., Shahid, S.A., Manzoor, M., 2013. Effect of microwave-assisted enzymatic aqueous extraction on the quality attributes of maize (Zea mays L.) seed oil. Asian. J. Chem. 25, 6280–6284. Atapour, M., Kariminia, H.R., 2011. Characterization and transesterification of Iranian bitter almond oil for biodiesel production. Acs Appl. Energy Mater. 88, 2377–2381. Atapour, M., Kariminia, H.R., Moslehabadi, P.M., 2014. Optimization of biodiesel production by alkali-catalyzed transesterification of used frying oil. Process Saf. Environ. 92, 179–185. Bolonio, D., Garcia-Martinez, M.J., Ortega, M.F., Lapuerta, M., Rodriguez-Fernandez, J., Canoira, L., 2019. Fatty acid ethyl esters (FAEEs) obtained from grapeseed oil: a fully renewable biofuel. Renew. Energ. 132, 278–283. Campos-Garcia, J., Vargas, A., Farias-Rosales, L., Miranda, A.L., Meza-Carmen, V., DiazPerez, A.L., 2018. Improving the organoleptic properties of a craft mezcal beverage by increasing fatty acid ethyl ester contents through ATF1 expression in an engineered Kluyveromyces marxianus UMPe-1 yeast. J. Agric. Food Chem. 66, 4469–4480. Cervero, J.M., Alvarez, J.R., Luque, S., 2014. Novozym 435-catalyzed synthesis of fatty acid ethyl esters from soybean oil for biodiesel production. Biomass Bioenerg. 61, 131–137. Chang, F., Hanna, M.A., Zhang, D.J., Li, H., Zhou, Q., Song, B.A., Yang, S., 2013. Production of biodiesel from non-edible herbaceous vegetable oil: xanthium sibiricum Patr. Bioresour. Technol. Rep. 140, 435–438. Conway, T.F., Earle, F.R., 1963. Nuclear magnetic resonance for determining oil content of seeds. J. Am. Oil Chem. Soc. 40, 265–268. da Silva, N.D., Batistella, C.B., Maciel, R., Maciel, M.R.W., 2009. Biodiesel production from castor oil: optimization of alkaline ethanolysis. Energ. Fuel. 23, 5636–5642. de Lima, A.L., Ronconi, C.M., Mota, C.J.A., 2016. Heterogeneous basic catalysts for biodiesel production. Catal. Sci. Technol. 6, 2877–2891. Demirbas, A., 2003. Biodiesel fuels from vegetable oils via catalytic and non-catalytic supercritical alcohol transesterifications and other methods: a survey. Energ. Convers. Manage. 44, 2093–2109. Demirbas, A., 2005. Biodiesel production from vegetable oils via catalytic and non-catalytic supercritical methanol transesterification methods. Prog. Energy Combust. Sci. 31, 466–487. Demirbas, A., 2017. Utilization of date biomass waste and date seed as bio-fuels source. Energy Sources Part A Recovery Util. Environ. Eff. 8, 756–760. Dorado, M.P., Ballesteros, E., De Almeida, J.A., Schellert, C., Lohrlein, H.P., Krause, R., 2002. An alkali-catalyzed transesterification process for high free fatty acid waste oils. Trans. ASAE 45, 525–529. Encinar, J.M., González, J.F., Rodríguez-Reinares, A., 2005. Biodiesel from used frying oil. Variables affecting the yields and characteristics of the biodiesel. Ind. Eng. Chem. Res. 44, 5491–5499. Encinar, J.M., González, J.F., Rodríguez-Reinares, A., 2007. Ethanolysis of used frying oil. Biodiesel preparation and characterization. Fuel Process. Technol. 88, 513–522. Fadhil, A.B., Alhayali, M.A., Saeed, L.I., 2017. Date (Phoenix dactylifera L.) palm stones as
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Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop
Biodiesel preparation from Phoenix tree seed oil using ethanol as acyl acceptor
T
⁎
Shangde Suna,b, , Jingjing Guoa,b, Xu Duanc a Lipid Technology and Engineering, School of Food Science and Engineering, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China b Provincal Key Laboratory for Transformation and Utilization of Cereal Resource, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China c Food and Biology Engineering College, Henan University of Science and Technology, No. 263, Kaiyuan road, Luoyang, Henan Province, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: Fatty acid ethyl ester Phoenix tree seed oil Ethanol Biodiesel Transesterfication Response surface methodology
Fatty acid ethyl ester (FAEE) is one kind of renewable biodiesel, which has lower emissions of mono-nitrogen oxides, lower smoke opacity, higher energy contents, lower pour, and cloud points. In this work, phoenix (Firmiana simplex L.) tree seed oil (PTSO) from Sterculiaceae was used as the novel feedstock to produce FAEE. Ethanol was used as fatty acyl acceptor and sodium hydroxide was employed as a catalyst. Response surface methodology was used to evaluate and optimize the effect of transesterification variables on FAEE yield. The effect of reaction variables on the transesterification was as follows: catalyst concentration > transesterification temperature > substrate ratio. Transesterfication variables were optimized as follows: 0.3% catalyst concentration with 10.8:1 substrate ratio (ethanol to PTSO, mol/mol) at 52.7 °C for 20 min. Under these optimized transesterification variables, the maximum FAEE yield (97.4 ± 1.7%) was obtained. These can provide an efficient and effective information for biodiesel preparation using PTSO as the novel feedstock.
1. Introduction With the depletion of non-renewable energy and the aggravation of environmental pollution, it is interesting of developing the economical and environment-friendly fuel alternatives for petroleum energy (Chang et al., 2013). Recently, biodiesel has been developed as a good alternative for diesel, which was attributed to the lower exhaust emissions, innocuous, renewable, and sulfur free (de Lima et al., 2016; Demirbas, 2005; Rintoul, 2010; Vyas et al., 2010). The main component of biodiesel is fatty acid alkyl ester, which can be prepared by the transesterfication of vegetable oil with short-chain alcohols (methanol or ethanol) (Cervero et al., 2014). Compared with methanol, ethanol is also a good fatty acyl acceptor for biodiesel production because ethanol is a renewable and environmentally friendly material (Demirbas, 2003; Kumar et al., 2010; Li et al., 2013; Stamenkovic et al., 2011; Verma and Sharma, 2016). Meanwhile, fatty acid ethyl ester (FAEE) has many advantages as renewable biodiesel, for example, lower emissions of mono-nitrogen oxides, lower smoke opacity, higher energy contents, lower pour, and cloud points (Rottig et al., 2010; Stamenkovic et al., 2011). In addition, FAEE can also be used as flavor compounds and
drugs in the pharmaceutical, food, and chemical industries (Bolonio et al., 2019; Campos-Garcia et al., 2018; Lapointe et al., 2019; Ndiaye et al., 2005). Therefore, FAEE preparation has been an important and interesting field. At present, more than 95% raw material of biodiesel production are edible oils, such as, corn (Zea mays L.) oil, soybean (Glycine max L.) oil, and other vegetable oils, which results in the imbalance between energy use with food consumption (Atapour and Kariminia, 2011; Goering et al., 1982). Therefore, the development of some new oil resources, such as, rubber (Hevea brasiliensis L.) seed oil, manketti (Ricinodendron rautanenii Schinz) oil, baobab (Adansonia digitata L.) oil, date palm (Phoenix dactylifera L.) oil, jatropha (Jatropha curcas L.) seed oil, manchurian apricot (Prunus mandshurica Skv.) oil, siberian apricot (Prunus sibirica L.) oil, and Chicha (Acanthopanax senticosus (Rupr. Et Maxim.) Harms) oil, as feedstock for biodiesel preparation, have attracted more attention (Amani et al., 2013; Demirbas, 2017; Farooq et al., 2018; Gomes Filho et al., 2015; Kamel et al., 2018; Khazaai et al., 2017; Modiba et al., 2014; Rutto and Enweremadu, 2011; Wang, 2013). Compared with date palm seed of the palm family in Middle Eastern and North African countries (Al-Muhtaseb et al., 2016, 2017; Jamil
⁎ Corresponding author at: Lipid Technology and Engineering, School of Food Science and Engineering, Henan University of Technology, Lianhua Road 100, Zhengzhou, 450001, Henan Province, PR China. E-mail addresses: [email protected] (S. Sun), [email protected] (J. Guo), [email protected] (X. Duan).
https://doi.org/10.1016/j.indcrop.2019.05.035 Received 9 January 2019; Received in revised form 11 May 2019; Accepted 13 May 2019 Available online 20 May 2019 0926-6690/ © 2019 Elsevier B.V. All rights reserved.
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Fig. 1. Transesterfication of phoenix tree seed oil (PTSO) with ethanol using NaOH catalyst to prepare fatty acid ethyl esters (FAEE).
et al., 2018), phoenix tree seed (PTS) is the novel resource from phoenix tree (Firmiana simplex L., a family of Sterculiaceae), which is a deciduous, medicinal, and ornamental plant in China, Korea, Europe, Japan, and USA (Woo et al., 2016; Li et al., 2009). And PTS has been used as the folk medicine to treat stomach disorders and diarrhea. The oil content of PTS is ˜30%, which is higher than that of date palm seed from date palm (10%), soybean (˜15%), corn (˜5%), and cottonseed (Gossypium spp.) (˜20%) (Anwar et al., 2013; Conway and Earle, 1963; Fadhil et al., 2017; Garca-Ayuso et al., 2000). The main fatty acids of the oil from PTS are linoleic acid (30.2%), oleic acid (22.2%), and palm acid (17.4%) (Sun and Li, 2016), which are different from those of date palm seed oil (lauric acid 11.36%, myristic acid 11.44%, palmitic acid 13.84%, stearic acid 6.56%, and oleic acid 51.45%) (Fadhil et al., 2017). Therefore, compared with these resources, PST was a novel resource for biodiesel preparation. In this work, phoenix tree seed oil (PTSO) was used as the new feedstock and ethanol was used as fatty acyl acceptor for FAEE preparation (Fig. 1). Sodium hydroxide is employed as a catalyst to catalyze the transesterification of PTSO with ethanol. The effects of reaction variables, such as NaOH concentration, reaction temperature, substrate ratio, and reaction time on FAEE yield were investigated. Response surface methodology (RSM) was used to evaluate and optimize the effect of the interactions of these reaction variables on FAEE yield.
catalyst (NaOH dissolved in amount of ethanol) was added to reaction mixture. The samples were taken out at set intervals and dissolved in 3 mL n-hexane, and then dried using anhydrous sodium sulfate, and followed by centrifugation. Finally, the supernatant liquid was collected and filtered using a microfilter (0.45 mm) for high temperature gas chromatography (GC) analysis.
2. Materials and methods
For evaluating the interaction effect of transesterification variables on FAEE yield, a 3-level-3-factor Box-Behnken design was used. In the RSM design, the factors and levels were molar ratio of ethanol to PTSO (5:1, 10:1 and 15:1 mol/mol), reaction temperature (30 °C, 50 °C and 70 °C), and catalyst concentration (0.1%, 0.3% and 0.5%; relative to the weight of all substrates).
2.4. Analysis methods According to the IUPAC methods, the acid value of PTSO was analyzed (Paquot and Hauntfenne, 1987). FAEE yield was determined by high temperature GC. For evaluating FAEE yield, high temperature GC (Agilent 7980B) with a flame ionization detector and DB-1H capillary column (30m × 0.25 mm, 0.1 μm of film thickness) was employed to analyze samples. High temperature GC conditions were as follows: the initial column temperature was 100 °C, and increased to 220 °C at 50 °C/min, then to 290 °C at 15 °C/min, and then increased to 320 °C at 40 °C/min, and at 320 °C for 8 min, finally to 360 °C at 20 °C/min, and at 360 °C for 6 min. The injector and detector temperatures were 350 °C and 400 °C, respectively. Carrier gas was helium at 1 mL/min. 2.5. Experimental design
2.1. Materials Phoenix tree seed (PTS) was provided by Jiangsu Xintai Wholesale Seed Industry Co. Ltd. (Jiangsu, China). N-hexane (chromatograph grade) was provided from Tianjin Guangfu Technology Development Co. Ltd. (Tianjin, China). Ethanol and sodium hydroxide were purchased from Tianjin Kemiou Chemical Reagent Co. Ltd. (Tianjin, China).
2.6. Statistical analysis The experimental data was analyzed by Design-Expert 8.0 and can be generalized by second-order polynomial model as follows:
2.2. Extraction of PTSO
3
Y = β0 +
Before the extraction, the impurities and excess moisture were removed from PTS. In order to obtain seed powder, the seeds were dried and crushed using a pulverizer, and then passed by a 40 mesh sieve. Next, petroleum ether was as the solvent to extract the oil from Phoenix tree seed powder. Finally, the solvent of supernatant was removed using a rotary evaporator. The oil obtained was used as feedstock for biodiesel preparation.
3
2
3
∑ βi Xi + ∑ βii Xi2 + ∑ ∑ i= 1
i=1
βij Xi XJ
i=1 j=i+1
(1)
Where Y is the predicted FAEE yield; Xi and Xj represent the transesterification variables. Regression coefficients β0, βi, βii, and βij are the intercept, linear, quadratic, and interaction terms, respectively. 3. Results and discussion
2.3. Transesterification of PTSO with ethanol
3.1. Effect of catalyst concentration on FAEE preparation
The mixture of PTSO with ethanol was mixed at 200 rpm and different temperatures (25–70 °C). The reaction was initiated when the
Sodium hydroxide (NaOH) has been widely used as catalyst for many reactions due to the cheap price and high activity (Saydut et al., 271
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Fig. 3. Effect of reaction temperature on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 0.4% catalyst concentration (relative on the weight of all substrates), 10:1 molar ratio of ethanol to PTSO (phoenix tree seed oil) and 200 rpm.
Fig. 2. Effect of catalyst concentration on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 10:1 molar ratio of ethanol to PTSO (phoenix tree seed oil), 200 rpm and 30 °C.
2010). However, the amount of free fatty acids (FFA) has an important influence on the activity of NaOH. Normally, low FFA content (< 2%) is necessary for NaOH-catalyzed reactions (Dorado et al., 2002; Rodriguez-Guerrero et al., 2013). In this work, the FFA content of PTSO was 0.46%, which suggested that NaOH can be used as the catalyst for the trasesterification of PTSO. A significant effect of NaOH concentration on the transesterification of PTSO with ethanol was found from Fig. 2. For evaluating the influence of NaOH concentration on FAEE yield, different NaOH concentrations from 0.05% (relative on the weight of all substrates) to 0.4% were used. In order to improve the activity of NaOH, before the reaction started, NaOH was firstly dissolved in ethanol to form alkoxide group, which can attack on the carbonyl carbon atom of the triglyceride to form a tetrahedral intermediate and result in a novel fatty acid ester and a diglyceride by the rearrangement of the tetrahedral intermediate (Saydut et al., 2010; Encinar et al., 2007; da Silva et al., 2009). Although small water was formed by the reaction between NaOH with ethanol, there was no significant effect on FAEE yield. Fig. 2 shows that the maximum FAEE yield was obtained after 20–30 min. Very low FAEE yield (< 5%) was obtained when low NaOH concentrations (0.05% and 0.1%) was used, which was due to the neutralization of the present FFA (0.46%) in PTSO for NaOH. After that, with the increase of NaOH concentration from 0.1% to 0.3%, FAEE yield increased rapidly from 2.5 ± 0.6% to 86.1 ± 1.4% (Fig. 2). When NaOH concentrations were higher than 0.3%, the transesterification reached equilibrium at 20 min and the maximum FAEE yield (˜84%) can also be obtained after 20 min. However, during the transesterification, the higher NaOH concentration, the more soap formed, which could intensify the emulsification of reaction system and made the separation of FAEE from product very difficult (Encinar et al., 2005; Atapour et al., 2014). Fig. 2 also shows that 0.3% NaOH concentration is enough for converting PTSO to FAEE by the transesterification, which is lower than that of manketti oil (1.02%), threated rubber seed oil (0.5%), and yellow sarson (Brassica campestris L.) oil (1%). These was ascribed to the fact that, compared with manketti oil (6% FFA content), threated rubber seed oil (2% FFA content), and yellow sarson oil (0.6% FFA content) (Rutto and Enweremadu, 2011; Ramadhas et al., 2005; Nosheen et al., 2013), the FFA content of PTSO (0.46%) was very low.
temperatures (25–70 °C) were used in the experiments (Fig. 3). With the increase of reaction temperature from 25 °C to 40 °C, FAEE yield increased from 82.8 ± 1.6% to 92.3 ± 0.9% at 20 min, and the time to achieve equilibrium shortened from 40 min to 20 min, which was due to the decrease of the effect of the viscosity of reaction system and mass transfer limitation. In general, temperature nearer to the boiling point of alcohol was optimum for the transesterification (Ma and Hanna, 1998). However, at high temperature, the side reaction to form soap by the saponification of triglycerides with NaOH was faster than the transesterification. Similar saponification reaction can be found in other reaction (Atapour and Kariminia, 2011). With the increase of temperature from 40 °C to 70 °C, FAEE yield increased only ˜5% at 20 min. Above all, 40 °C is the best reaction temperature for FAEE preparation, which was lower than the optimal reaction temperature of frying oil (78 °C), soybean oil (70 °C), and yellow sarson oil (75 °C) (Encinar et al., 2007; Nosheen et al., 2013; Tippayawong et al., 2005). 3.3. Effect of molar ratio of ethanol to PTSO Fig. 4 shows that the increase of substrate ratio has a great effect on FAEE formation. With the increase of substrate ratio from 3:1 to 15:1, a rapid increase of FAEE yield from 68.7 ± 1.2% to 99.3 ± 0.9% was found at 20 min. These results were ascribed to the fact that excess amount of ethanol will increase FAEE conversion by shifting reaction
3.2. Effect of transesterification temperature Reaction temperature can not only accelerate the reaction, but also reduce the effect of mass transfer limitation. However, high temperature also resulted in the evaporation of solvent. In order to evaluate the influence of temperature on the transesterification of PTSO, different
Fig. 4. Effect of molar ratio of ethanol to PTSO (phoenix tree seed oil) on FAEE (fatty acid ethyl esters) yield. Reaction conditions: 0.4% catalyst concentration (relative to the weight of substrates), 60 °C and 200 rpm. 272
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e2.52X2X3 e42.43X12 e3.93X22 e5.73X32
Table 1 Box–Behnken design and results of FAEE yield as affected by molar ratio of substrates, reaction temperature, and catalyst concentration. Trial
X1 (%) Catalyst concentration
X2 (°C) Reaction temperature
X3 (mol/mol, ethanol to PTSO)
FAEE yield (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
0.1(-1) 0.1(-1) 0.3(0) 0.3(0) 0.5(1) 0.5(1) 0.3(0) 0.3(0) 0.3(0) 0.5(1) 0.3(0) 0.3(0) 0.3(0) 0.3(0) 0.5(1) 0.1(-1) 0.1(-1)
50(0) 50(0) 50(0) 50(0) 50(0) 50(0) 70(1) 30(-1) 50(0) 30(-1) 50(0) 30(-1) 50(0) 70(1) 70(1) 30(-1) 70(1)
5(-1) 15(1) 10(0) 10(0) 5(-1) 15(1) 15(1) 5(-1) 10(0) 10(0) 10(0) 15(1) 10(0) 5(-1) 10(0) 10(0) 10(0)
1.1 ± 0.3 1.4 ± 0.2 92.7 ± 2.1 92.3 ± 1.8 79.4 ± 1.2 95.0 ± 1.4 95.5 ± 2.4 64.9 ± 1.8 92.5 ± 1.5 89.2 ± 1.6 92.5 ± 1.3 89.7 ± 0.4 92.2 ± 1.2 80.8 ± 1.5 92.5 ± 0.6 1.1 ± 0.2 1.3 ± 0.4
(2)
Fig. 5A shows the influence of reaction temperature, NaOH concentration, and their mutual interaction on FAEE yield with 10:1 substrate ratio of ethanol to PTSO. Raising temperature and substrate ratio were beneficial for FAEE formation. When the moderate NaOH concentration (0.3–0.4%) and temperature (38–54 °C) were used, the high FAEE yields (> 92.2%) were obtained. Fig. 5B shows the changes of FAEE yield with varying substrate ratio and NaOH concentration. When substrate ratio was 9:1 (mol/mol), FAEE yield rapidly increased with the increase of NaOH concentration from 0.1% to 0.4%. The higher FAEE yields (> 98.8%) were obtained with lower substrate ratio (7:1–11:1 mol/mol) and higher NaOH concentration (0.3–0.4%). Fig. 5C shows the relationship of varying substrate ratio and transesterification temperature on FAEE yield with 0.3% NaOH concentration. The FAEE yield increased with the increase of substrate ratio from 5:1 to 15:1 (mol/mol). However, a further increasing of substrate ratio (> 15:1 mol/mol) would lead to a decline of FAEE yield. The higher FAEE yield (> 90.9%) appeared at moderate reaction temperature (46–54 °C) and higher substrate ratio (9:1–13:1 mol/mol).
3.5. Optimum transesterification conditions and model verification
equilibrium to the formation of FAEE (Shimada et al., 2002). With further increase of substrate ratio (≥15:1), only little improvement on FAEE yield (˜99.4%) was obtained at 20 min. Excess amount of ethanol can also increase the solubility of glycerol and result in a decrease in FAEE yield (Murugesan et al., 2009; Fillieres et al., 1995). Therefore, 15:1 substrate ratio was the best choice for the reaction, which was similar with that of castor (Ricinus communis L.) oil (16:1) (da Silva et al., 2009).
In order to verify the adequacy of the optimal reaction variables and the predicted models, experiments were carried out under the optimized conditions. Transesterification conditions were optimized as follows: transesterification temperature 52.7 °C, catalyst concentration 0.3%, reaction time 20 min and 10.8:1 substrate ratio. Under these optimal variables, the maximum FAEE yield (97.4 ± 1.7%) was achieved and it was well accorded with the predicted FAEE yield (98.9%), which indicated the validation of the model. The optimal NaOH concentration (0.3%) was lower than that of Leung and Guo (1.1% NaOH concentration) (2006) used frying oil with 94.0% FAEE yield, which was ascribed to the higher FFA content (1.1%) in the frying oil. The best temperature for FAEE preparation using PTSO was 52.7 °C, which was lower than that of Encinar et al. (2005) (78 °C, 1% KOH concentration) and Tippayawong et al. (2005) (70 °C, 1.0% KOH concentration) with only ˜93% FAEE yield using frying oil and soybean oil, respectively. Compared with the previous reports for FAEE preparation, 97.4 ± 1.7% FAEE yield can be achieved in 20 min, which was very faster than that of the previous methods for biodiesel preparation (3 h for CaO as catalyst and soybean oil as raw material (Liu et al., 2008), 1 h for sodium methoxide as catalyst and baobab oil as raw material (Modiba et al., 2014)). The work can provide an efficient method for biodiesel preparation using PTSO as raw material.
3.4. Response surface analysis and model fitting In the analysis of multifactor quantitative experiment, RSM was employed to analyze the regression relationship between dependent and independent variables, which is used to optimize experimental variables (Syam et al., 2016). Table 1 shows the experimental results obtained from the model. The data were regressed by employing a quadratic polynomial equation, which was used to evaluate the mutual relationship between FAEE yield and transesterification variables. Table 2 shows the ANOVA analysis for the model. Due to the low Pvalue (P < 0.001), the model was adequate to explain the mutual relationship between reaction variables with FAEE yield. The effect of transesterification variables on FAEE yield decreased in the order of NaOH concentration > substrate ratio > transesterification temperature. Regression equation explaining FAEE yield was given as follow: Y (%)=92.38+43.90X1 e3.15X2 + 6.93X3 + 0.77X1X2 + 3.83X1X3 Table 2 Analysis of variance (ANOVA) for quadratic model to FAEE yield. Sourse
Sum of squares
Degrees of freedom
Mean square
F value
Prob > F
Model X1 X2 X3 X1 X2 X1 X3 X2 X3 X12 X22 X32 Residual Lack of fit Total R2 = 0.9951
23998.68 15417.68 79.38 383.65 2.40 58.52 25.50 7579.34 64.95 138.12 118.06 117.87 24116.74
9 1 1 1 1 1 1 1 1 1 7 3 16 RAdj2 = 0.9888
2666.52 15417.68 79.38 383.65 2.40 58.52 25.50 7579.34 64.95 138.12 16.87 39.29
158.11 914.16 4.17 22.75 0.14 3.47 1.51 449.40 3.83 8.19
< 0.0001 < 0.0001 0.0667 0.0020 0.7170 0.1048 0.2585 < 0.0001 0.0905 0.0243
835.96
< 0.0001
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Fig. 5. (A) 3D surface plots between reaction temperature with NaOH concentration for FAEE (fatty acid ethyl esters) yield with 10:1 substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)).Fig. (B) 3D surface plots between substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)) with NaOH concentration for FAEE (fatty acid ethyl esters) yield at 50 °C. Fig. (C) 3D surface plots between reaction temperature with substrate ratio (molar ratio of ethanol to PTSO (phoenix tree seed oil)) for FAEE (fatty acid ethyl esters) yield with 0.3% NaOH concentration (relative to the total weight of substrates).
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4. Conclusions
a potential new feedstock for liquid bio-fuels production. Fuel 210, 165–176. Farooq, M., Ramli, A., Naeem, A., Mahmood, T., Ahmad, S., Humayun, M., Islam, M.G.U., 2018. Biodiesel production from date seed oil (Phoenix dactylifera L.) via egg shell derived heterogeneous catalyst. Chem. Eng. Res. Des. 132, 644–651. Fillieres, R., Benjelloun-Mlayeh, B., Delmas, M., 1995. Ethanolysis of rapeseed oil: quantitation of ethyl esters, mono-, di- and triglycerides and glycerol by high-performance size-exclusion chromatography. J. Am. Oil Chem. Soc. 72, 427–432. Garca-Ayuso, L.E., Velasco, J., Dobarganes, M.C., Luque de Castro, M.D., 2000. Determination of the oil content of seeds by focused microwave-assisted soxhlet extraction. Chromatographia 52, 103–108. Goering, C.E., Schwab, A.W., Daugherty, M.J., Pryde, E.H., Heakin, A.J., 1982. Fuel properties of eleven vegetable oils. Appl. Eng. Agric. 25, 1472–1483. Gomes Filho, J.C., Peiter, A.S., Pimentel, W.R.O., Soletti, J.I., Carvalho, S.H.V., Meili, L., 2015. Biodiesel production from Sterculia striata oil by ethyl transesterification method. Ind. Crop. Prod. 74, 767–772. Jamil, F., Al-Muhatseb, A., Myint, M.T.Z., Al-Hinai, M., Al-Haj, L., Baawain, M., Al-Abri, M., Kumar, G., Atabani, A.E., 2018. Biodiesel production by valorizing waste Phoenix dactylifera L. Kernel oil in the presence of synthesized heterogeneous metallic oxide catalyst (Mn@MgO-ZrO2). Energ. Convers. Manage. 155, 128–137. Kamel, D.A., Farag, H.A., Amin, N.K., Zatout, A.A., Ali, R.M., 2018. Smart utilization of jatropha (Jatropha curcas Linnaeus) seeds for biodiesel production: optimization and mechanism. Ind. Crop. Prod. 111, 407–413. Kumar, D., Kumar, G., Singh, P.C.P., 2010. Fast, easy ethanolysis of coconut oil for biodiesel production assisted by ultrasonication. Ultrason. Sonochem. 17, 555–559. Lapointe, J., BPharm, H.L., Aziz, S., Jordan, H., Hegele, R.A., Lemieux, P., 2019. A singledose, comparative bioavailability study of a formulation containing OM3 as phospholipid and free fatty acid to an ethyl ester formulation in the fasting and fed states. Clin. Ther. 41, 426–444. Li, Z.Z., Tang, X.W., Chen, Y.M., Wei, L.M., Wang, Y., 2009. Activation of Firmiana simplex leaf and the enhanced Pb (II) adsorption performance: equilibrium and kinetic studies. J. Hazard. Mater. 169, 386–394. Li, Q., Xu, J., Du, W., Li, Y., Liu, D., 2013. Ethanol as the acyl acceptor for biodiesel production. Renew. Sust. Energ. Rev. 25, 742–748. Liu, X.J., He, H.Y., Wang, Y.J., Zhu, S.L., Piao, X.L., 2008. Transesterification of soybean oil to biodiesel using CaO as a solid base catalyst. Fuel 87, 216–221. Ma, F., Hanna, M.A., 1998. The effects of catalyst, free fatty acids and water on transesterification of beef tallow. Ind. Eng. Chem. Res. 41, 1261–1264. Modiba, E., Osifo, P., Rutto, H., 2014. Biodiesel production from baobab (Adansonia digitata L.) seed kernel oil and its fuel properties. Ind. Crop. Prod. 59, 50–54. Murugesan, A., Umarani, C., Chinnusamy, T.R., Krishnan, M., Subramanian, R., Neduzchezhain, N., 2009. Production and analysis of bio-diesel from non-edible oilsa review. Renew. Sust. Energ. Rev. 13, 825–834. Ndiaye, P.M., Tavares, F.W., Dalmolin, I., Dariva, C., Oliveira, D., Oliveira, J.V., 2005. Vapor pressure data of soybean oil, castor oil, and their fatty acid ethyl ester derivative. J. Chem. Eng. Data 50, 330–333. Nosheen, A., Bano, A., Ullah, F., 2013. The optimization of biodiesel production from yellow sarson (Brassica campestris L.) oil. Energy Sources Part A-Recovery Util. Environ. Eff. 35, 278–281. Paquot, C., Hauntfenne, A., 1987. IUPAC Standard Methods for the Analysis of Oils, Fats and Derivatives. Blackwell, London. Ramadhas, A.S., Jayaraj, S., Muraleedharan, C., 2005. Biodiesel production from high FFA rubber seed oil. Fuel 84, 335–340. Rintoul, S., 2010. Biofuels blend measurements with portable mid-infrared analyzers. INFORM-International News on Fats, Oils and Related Materials. 21 (8), 521–522. Rodriguez-Guerrero, J.K., Rubens, M.F., Rosa, P.T.V., 2013. Production of biodiesel from castor oil using sub and supercritical ethanol: effect of sodium hydroxide on the ethyl ester production. J. Supercrit. Fluid. 83, 124–132. Rottig, A., Wenning, L., Broker, D., Steinbuchel, A., 2010. Fatty acid alkyl esters: perspectives for production of alternative biofuels. Appl. Microbiol. Biot. 85, 1713–1733. Rutto, H.L., Enweremadu, C.C., 2011. Optimization of production variables of biodiesel from Manketti using response surface methodology. Int. J. Green Energy 8, 768–779. Saydut, A., Kafadar, A.B., Tonbul, Y., Kaya, C., Aydin, F., Hamamci, C., 2010. Comparison of the biodiesel quality produced from refined sunflower (Helianthus annuus L.) oil and waste cooking oil. Energ. Explor. Exploit. 28, 499–512. Shimada, Y.J., Watanabe, Y.M., Sugihara, A.K., Tominaga, Y., 2002. Enzymatic alcoholysis for biodiesel fuel production and application of the reaction to oil processing. J. Mol. Catal. B-Enzym. 17, 133–142. Stamenkovic, O.S., Velickovic, A.V., Veljkovic, V.B., 2011. The production of biodiesel from vegetable oils by ethanolysis: current state and perspectives. Fuel 11, 3141–3155. Sun, S.D., Li, X.L., 2016. Physicochemical properties and fatty acid profile of Phoenix tree Seed and its oil. J. Am. Oil Chem. Soc. 93, 1111–1114. Syam, A.M., Rashid, U., Yunus, R., Hamid, H.A., Al-Resayes, S.I., Nehdi, I.A., AlMuhtaseb, A.H., 2016. Conversion of Oleum papaveris seminis oil into methyl esters via esterification process: optimization and kinetic study. Grasas Aceites 67, 1–9. Tippayawong, N., Kongjareon, E., Jompakdee, W., 2005. Ethanolysis of soybean oil into biodiesel: process optimization via central composite design. J. Mech. Sci. Technol. 19, 1902–1909. Verma, P., Sharma, M.P., 2016. Comparative analysis of effect of methanol and ethanol on Karanja biodiesel production and its optimization. Fuel 180, 164–174. Vyas, A.P., Verma, J.L., Subrahmanyam, N., 2010. A review on FAME production processes. Fuel 89, 1–9. Wang, L.B., 2013. Properties of Manchurian apricot (Prunus mandshurica Skv.) and Siberian apricot (Prunus sibirica L.) seed kernel oils and evaluation as biodiesel feedstocks. Ind. Crop. Prod. 50, 838–843. Woo, K.W., Suh, W.S., Subedi, L., Kim, S.Y., Kim, A., Lee, K.R., 2016. Bioactive lignan derivatives from the stems of Firmiana simplex. Bioorg. Med. Chem. Lett. 26, 730–733.
In this work, biodiesel can be successfully prepared using PTSO as the new material and ethanol as fatty acyl acceptor. NaOH was used to catalyze the transesterification of PTSO with ethanol. The effect of transesterification conditions on FAEE yield was evaluated and optimized using RSM. The maximum FAEE yield (97.4 ± 1.7%) from PTSO can be obtained under the optimal conditions as follows: transesterification temperature 52.7 °C, catalyst concentration 0.3%, reaction time 20 min and 10.8:1 substrate ratio. And the influence of transesterification conditions on the reaction decreased in the order of NaOH concentration > substrate ratio > transesterification temperature. A quadratic regression model between reaction conditions with FAEE yield was also achieved from RSM. Acknowledgements The authors gratefully acknowledge financial support from National Natural Science Foundation of China (31771937) and Provincal Key Laboratory for Transformation and Utilization of Cereal Resource (PL2016008). The authors thank Jianxing Sun and Meng Wang for their help with the experiments on FAEE yield determination. References Al-Muhtaseb, A.H., Jamil, F., Al-Haj, L., Al-Hinai, M.A., Baawain, M., Myint, M.T.Z., Rooney, D., 2016. Efficient utilization of waste date pits for the synthesis of green diesel and jet fuel fractions. Energ. Convers. Manage. 127, 226–232. Al-Muhtaseb, A.H., Jamil, F., Myint, M.T.Z., Baawain, M., Al-Abri, M., Dung, T.N.B., Kumar, G., Ahmad, M.N.M., 2017. Cleaner fuel production from waste Phoenix dactylifera L. Kernel oil in the presence of a bimetallic catalyst: optimization and kinetics study. Energ. Convers. Manage. 146, 195–204. Amani, M.A., Davoudi, M.S., Tahvildari, K., Nabavi, S.M., Davoudi, M.S., 2013. Biodiesel production from Phoenix dactylifera as a new feedstock. Ind. Crop. Prod. 43, 40–43. Anwar, F., Yaqoub, A., Shahid, S.A., Manzoor, M., 2013. Effect of microwave-assisted enzymatic aqueous extraction on the quality attributes of maize (Zea mays L.) seed oil. Asian. J. Chem. 25, 6280–6284. Atapour, M., Kariminia, H.R., 2011. Characterization and transesterification of Iranian bitter almond oil for biodiesel production. Acs Appl. Energy Mater. 88, 2377–2381. Atapour, M., Kariminia, H.R., Moslehabadi, P.M., 2014. Optimization of biodiesel production by alkali-catalyzed transesterification of used frying oil. Process Saf. Environ. 92, 179–185. Bolonio, D., Garcia-Martinez, M.J., Ortega, M.F., Lapuerta, M., Rodriguez-Fernandez, J., Canoira, L., 2019. Fatty acid ethyl esters (FAEEs) obtained from grapeseed oil: a fully renewable biofuel. Renew. Energ. 132, 278–283. Campos-Garcia, J., Vargas, A., Farias-Rosales, L., Miranda, A.L., Meza-Carmen, V., DiazPerez, A.L., 2018. Improving the organoleptic properties of a craft mezcal beverage by increasing fatty acid ethyl ester contents through ATF1 expression in an engineered Kluyveromyces marxianus UMPe-1 yeast. J. Agric. Food Chem. 66, 4469–4480. Cervero, J.M., Alvarez, J.R., Luque, S., 2014. Novozym 435-catalyzed synthesis of fatty acid ethyl esters from soybean oil for biodiesel production. Biomass Bioenerg. 61, 131–137. Chang, F., Hanna, M.A., Zhang, D.J., Li, H., Zhou, Q., Song, B.A., Yang, S., 2013. Production of biodiesel from non-edible herbaceous vegetable oil: xanthium sibiricum Patr. Bioresour. Technol. Rep. 140, 435–438. Conway, T.F., Earle, F.R., 1963. Nuclear magnetic resonance for determining oil content of seeds. J. Am. Oil Chem. Soc. 40, 265–268. da Silva, N.D., Batistella, C.B., Maciel, R., Maciel, M.R.W., 2009. Biodiesel production from castor oil: optimization of alkaline ethanolysis. Energ. Fuel. 23, 5636–5642. de Lima, A.L., Ronconi, C.M., Mota, C.J.A., 2016. Heterogeneous basic catalysts for biodiesel production. Catal. Sci. Technol. 6, 2877–2891. Demirbas, A., 2003. Biodiesel fuels from vegetable oils via catalytic and non-catalytic supercritical alcohol transesterifications and other methods: a survey. Energ. Convers. Manage. 44, 2093–2109. Demirbas, A., 2005. Biodiesel production from vegetable oils via catalytic and non-catalytic supercritical methanol transesterification methods. Prog. Energy Combust. Sci. 31, 466–487. Demirbas, A., 2017. Utilization of date biomass waste and date seed as bio-fuels source. Energy Sources Part A Recovery Util. Environ. Eff. 8, 756–760. Dorado, M.P., Ballesteros, E., De Almeida, J.A., Schellert, C., Lohrlein, H.P., Krause, R., 2002. An alkali-catalyzed transesterification process for high free fatty acid waste oils. Trans. ASAE 45, 525–529. Encinar, J.M., González, J.F., Rodríguez-Reinares, A., 2005. Biodiesel from used frying oil. Variables affecting the yields and characteristics of the biodiesel. Ind. Eng. Chem. Res. 44, 5491–5499. Encinar, J.M., González, J.F., Rodríguez-Reinares, A., 2007. Ethanolysis of used frying oil. Biodiesel preparation and characterization. Fuel Process. Technol. 88, 513–522. Fadhil, A.B., Alhayali, M.A., Saeed, L.I., 2017. Date (Phoenix dactylifera L.) palm stones as
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