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Evaluation of guindilla oil (Guindilia trinervis Gillies ex Hook. et Arn.) for biodiesel production
Fuel 89 (2010) 3785–3790
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Evaluation of guindilla oil (Guindilia trinervis Gillies ex Hook. et Arn.) for biodiesel production Ricardo San Martín a,*, Teófilo de la Cerda a, Adolfo Uribe a, Paola Basilio a, Miguel Jordán b, Doris Prehn c, Marlene Gebauer c a b c
Pontificia Universidad Católica de Chile, Faculty of Engineering, Department of Chemical and Bioprocess Engineering, Av. Vicuña Mackenna 4860, Santiago, Chile Universidad Mayor, Campus Huechuraba, Camino La Pirámide 5750, Huechuraba, Santiago, Chile Pontificia Universidad Católica de Chile, Faculty of Agronomy, Av. Vicuña Mackenna 4860, Santiago, Chile
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Article history: Received 12 January 2010 Received in revised form 10 July 2010 Accepted 14 July 2010 Available online 30 July 2010 Keywords: Biodiesel Guindilla Guindilia trinervis
a b s t r a c t Guindilla plants (Guindilia trinervis Gillies ex Hook. et Arn.) are small shrubs that grow wildly in the mountains of Central Chile in soils and climates not suitable for agriculture. Whole guindilla seeds contain 28–29% w/w oil. Cotyledons represent 45% w/w of the seed and contain 63–64% w/w oil. Main unsaturated fatty acids are oleic (63% w/w), linoleic (8% w/w) and gadoleinic (9.5% w/w), while main saturated fatty acids are palmitic (9.1% w/w) and stearic (3.1% w/w). The content of free fatty acids was 0.06%. Transesterification reactions yielded a biodiesel with ester content >99%; cetane number 59; oxidative stability at 110 °C, 18.9 h; kinematic viscosity at 40 °C, 4.867 mm2/s; cold filter plugging point, CFPP + 4 °C; sulfur content 1.0 mg/kg; sulfated ash < 0.01% p/p; acid value 0.024 mg KOH/g and phosphorous content (<0.5 mg/kg). All values were within European and US specifications. The relatively high CFPP value limits the use of unblended guindilla biodiesel to high temperature weather locations. The high oxidative stability is probably due to the low content (8.8% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3). Guindilla plants grow wildly with estimated yields of 1000 L oil/ha. Plant improvement programs could make these plants a viable alternative for biodiesel production. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Worldwide there is a growing interest on developing alternative energy sources such as biodiesel to overcome high oil costs and future shortage. According to the US standard ASTM D6751 biodiesel is defined as a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats [1]. This fuel is obtained from an oil or fat by a transesterification reaction with glycerol as a by-product [2]. The European biodiesel standard EN-14214 refers to fatty acid methyl esters (FAME) as fuel [3]. Generally, the most abundant vegetable oil in a particular region is the most common feedstock [4]. Thus, in Europe rapeseed and sunflower are predominantly used, palm oil predominates in tropical countries, and soybean and animal fats in the USA [5]. In Chile, the interest on biodiesel production is high since the country depends largely on imported energy resources. Rapeseed is being considered for the production of biodiesel, but its cultivation requires primarily agricultural land. Other high oil yield plants such as Jatropha curcas are being examined, particularly in the
* Corresponding author. Tel.: +56 2 354 4927; fax: +56 2 354 5803. E-mail address: [email protected] (R.S. Martín). 0016-2361/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2010.07.017
Northern semi-arid parts of the country. However, so far, no industrial biodiesel plants have been established in the country. The objective of this project is to evaluate a relatively unknown oil-bearing plant (Guindilia trinervis Gillies ex Hook. et Arn. Sapindaceae, common name guindilla), native of Chile and Argentina, for the production of biodiesel. One of the main advantages of guindilla plants are their ability to survive and thrive in soils and climates regarded unsuitable for agriculture. The genus Guindilia (formerly Valenzuela) is comprised of three species which are restricted to Chile and Argentina [6]. Guindilla is a small shrub that grows abundantly at altitudes over 1500 m, and it is usually covered by snow during the winter. In Chile it is found in the central region of the country, specifically in the mountains of the V, VI, VII and metropolitan regions (Santiago). It is more abundant in sunny areas and flowers between September and November; the fruits mature between December and February. Fig. 1 shows a picture of guindilla plants in their natural habitat. Fig. 2 shows the flowers of guindilla, Fig. 3 the fruits and Fig. 4 the cotyledons. Each adult plant occupies an area of about 1.5 1.5 m. The plant has simple, sessile leaves and a three parted fruit (1–1.5 cm in diameter) in which one or two carpels sometimes abort to make the fruit apparently one seeded [6]. The seed has two cotyledons wrapped inside a seedcoat and contained in a round, thick hull 1–1.5 cm in diameter. Cotyle-
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Fig. 1. Guindilla plants in their natural habitat. Altitude: 1500 m, nearby Santiago, Chile.
pids [8] the research was abandoned. Based on its high oil content and fatty acid composition, the goal of this work is to assess the potential of guindilla oil for the production of biodiesel. 2. Methods 2.1. Guindilla seeds Guindilla seeds were collected from the ground during April, 2008 in the Andes Mountains surrounding the city of Santiago at an altitude of 1511 m. The exact location was characterized as Lagunillas 1, with GPS coordinates: S 33° 37.848´; W 070° 18.601´. The seeds were fractured and manually open to separate the hull and the cotyledons. The seed coat was not removed. The average moisture content of the cotyledons was determined by drying comminuted material at 103 ± 2 °C until constant weight. 2.2. Oil extraction
Fig. 2. Flowers of guindilla.
don cells are filled with oil globules or spherosomes. Guindilla oil composition was studied 25 years ago to evaluate its potential for human consumption [7]. The research indicated that the oil yield of whole seeds (cotyledons plus seed hulls) is about 30% w/ w and that under natural conditions it may be possible to obtain 3.5–4.0 tons of whole seeds/ha or about 1000 L oil/ha. Main fatty acids were 62.3% oleic, 12.9% gadoleic, 10.1% linoleic and 9.6% palmitic [8]. However due to the presence of potentially toxic cyanoli-
Guindilla seeds (cotyledons) were extracted in a continuous laboratory scale screw press (IBG Monforts Oekotec, Model Komet CA59 G, Monchengladbach, Germany). The operating variables were press head temperature (ranging from room temperature to 120 °C), diameter of pellet outlet hole – 0.2, 0.35 and 0.5 cm – and seed feeding rate. Preliminary experiments were performed to maximize oil yields. The most consistent results were obtained at a feeding rate of 1.2 kg seeds/h, press head temperature of 60 °C and a diameter of the pellet outlet hole of 0.5 cm. Lower temperatures reduced oil yields; higher temperatures and lower outlet hole diameters partially burnt the seed cake; higher feeding rates decreased oil yields. Following the first pressing, the resulting seed cake was re-extracted (second pressing). The remaining cake was then placed in a Soxhlet extractor operated with hexane to extract the residual oil. The size of the extractor body was 2 L. For each extraction 900 g of seed cake were contacted with 1.5 L of hexane. Extraction time vs. oil yield was tested at 4, 6 and 8 h. Oil yields at 6 h were 25% higher than at 4 h. Longer extraction times did not improved oil yields. Hence, an extraction time of 6 h was chosen for all experiments. Hexane was removed in a Rotavapor unit with a water bath temperature of 50 °C and 3.07 kPa of vacuum for 1 h.
R.S. Martín et al. / Fuel 89 (2010) 3785–3790
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Fig. 3. Guindilla seeds in their natural habitat, altitude 1511 m. Lagunillas, Chile.
To remove residual solvent, the oil was sparged at atmospheric pressure with helium for 1 h. 2.3. Oil refining Preliminary experiments considered water degumming followed by acid degumming. Water degumming was performed using 2.5% w/w distilled water, 80 °C and strong mechanical agitation for 40 min. The mixture was then placed overnight in separation funnels. The supernatant was collected and filtered through Whatman 4 to remove remaining insoluble impurities. Acid degumming was performed contacting the oil with 0.2% w/w phosphoric acid (85% w/w), and subjected to a similar procedure than water degumming. Since the impurities removed during acid degumming were negligible, in subsequent experiments this procedure was not used. This is consistent with the low content of phospholipids present in guindilla oil (see Section 3). 2.4. Transesterification reaction The transesterification reaction was performed using methanol and 30% w/w sodium methoxide solution (Na-Metylat, BASF) as
Fig. 4. Guindilla cotyledons.
catalyst. Methanol concentration was based on the saponification index of the oil of 192 [7] and a 5.5:1 M ratio (moles methanol: moles of tri-glycerides). The reaction was performed in a 1 L glass vessel equipped with mechanical agitation and reflux condenser open to atmospheric pressure. The reactor was immersed in a water bath at 80 °C. Each reaction was performed with 180 g of oil, 36 g of methanol and 6 g of 30% w/w sodium methoxide solution. This corresponded to 1.8 g of sodium methoxide and a 1% w/w ratio of sodium methoxide to oil. After 2 h of reaction, the reactor contents were placed in a 1 L glass separation funnel for 15 h at room temperature. The lower phase containing glycerol was discarded. The upper biodiesel phase was collected and washed with water using 2:1 water to biodiesel volumetric ratio. Contacting was performed at 70 °C in a 1 L separation funnel with gentle mixing. The mixture was then settled for 15 min, and the water and biodiesel phases separated. This washing procedure was repeated 3 times.
2.5. Analysis All analyzes were performed following European biodiesel standards at the facilities of the ASG Analytik laboratories (Neusäss, Germany). The amount of free glycerol, mono, di and triglycerides in the biodiesel was determined using EN 14105. 1,2,4-butanetriol was used as the standard for the determination of free glycerol, while 1,2,3,-tricaproylglycerol (tricaprin) was used for the determination of the glycerides (mono-,di- and tri-). Cetane number was determined usingthe standard EN 15195. Oxidative stability at 110 °C using the Rancimat method was obtained using the standard EN-14112. Kinematic viscosity at 40 °C was obtained using standard EN ISO 3104. Flash point was determined using standard EN ISO 3679. Cold filter plugging point (CFPP) was determined using standard EN 116. Sulfur content, sulfated ash, acid value and phosphorous content were determined using standards EN ISO 20884, EN ISO 3987, EN 14104 and EN 14107, respectively. Fatty acid profile of the oil was analyzed using EN 14103 modified so that the samples were methylated before analysis. The free fatty acids and phospholipids content of the oil were determined using AOAC methods [9].
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R.S. Martín et al. / Fuel 89 (2010) 3785–3790 Table 2 Free and total glycerol in guindilla biodiesel. Method EN 14105.
3. Results and discussion 3.1. Oil extraction and composition Cotyledons represent 45% w/w of whole guindilla seeds and the seed hull 55% w/w. The average natural moisture content of the cotyledons was 3.5% w/w. Press extraction oil yields of the cotyledons were 30.5% w/w for the first pressing and 19.1% w/w for the second pressing. Solvent extraction gave an additional 14% w/w. Thus, the overall extraction yield from the cotyledons was 63.6% w/w, which agrees with previous analyzes, e.g. 67% w/w oil [7]. Thus, the average oil yield based on whole seeds (cotyledons and hulls) was 28.6% w/w. The oil extracted with hexane contained 0.6–0.7% phospholipids, while the pressed oil contained 0.1–0.3% phospholipids. These values are low in relation to other feedstocks such as rapeseed and soybean oil. Due to this, the refining process using just water degumming was sufficient. Table 1 shows the fatty acid profile of oil samples obtained by solvent and press extraction. No significant differences in composition are observed. Main unsaturated fatty acids are oleic (63% w/ w), linoleic (8% w/w) and gadoleinic (9.5% w/w), while main saturated fatty acids are palmitic (9.1% w/w) and stearic (3.1% w/w). The overall content of unsaturated and saturated fatty acids are 82.4% and 17.6% w/w, respectively. These results are in close agreement with previous analyzes, e.g.: oleic, 62.3%; gadoleinic 12.5%; linoleic, 10.1%, and palmitic, 9.6% [7]. In relation to other common biodiesel feedstock such as rapeseed oil, guindilla oil contains a similar content of oleic acid (63% w/w), but exhibits a high content (9.5% w/w) of gadoleinic acid (C20:1), as well as arachinic acid (4.6% w/w; C20:0). It also contains low amounts (8.5% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3) in relation to rapeseed oil, e.g. 27.8% w/w [10]. 3.2. Production of biodiesel Average production yields of biodiesel were 85–90% w/w. Soap formation was not observed, in agreement with the low content of free fatty acids in the oil, e.g. 0.06%. These yields are acceptable under laboratory conditions, and can be improved significantly industrially, where more efficient recovery operations can be implemented. Table 2 shows the amount of free glycerol, mono, di and tri-glycerides and total glycerol in the biodiesel. All parameters comply with the European standards and also with US standard ASTM D-6571 that sets a limit for free glycerin of 0.02% and for total glycerin (free and bound) of 0.24%. This indicates that the extent of the transesterification reaction is adequate and that there is no excess of glycerol in the biodiesel. The ester content
Table 1 Fatty acid profile of guindilla oil obtained through solvent and press extraction Analysis method: EN 14103 modified (fatty acids were methylated before analysis). Parameter
Solvent extraction % w/w
Press extraction % w/w
C12:0 Lauric acid C14:0 Myristic acid C16:0 Palmitic acid C16:1 Palmitoleic acid C18:0 Stearic acid C18:1 Oleic acid C18:2 Linoleic acid C18:3 Linolenic acid C20:0 Arachidic acid C20:1 Gadoleinic acid C22:0 Behenic acid C22:1 Erucic acid C24:0 Tetracosanoic acid C24:1 Tetracosenic acid
<0.1 <0.1 9.2 0.1 3.1 62.9 8.0 0.9 4.7 9.7 0.4 0.9 0.1 <0.1
<0.1 <0.1 9.0 0.1 3.2 63.7 7.6 0.8 4.7 9.5 0.4 0.8 0.1 <0.1
Parameter
Solvent extraction % (w/w)
EN-14214–03 Press extraction Specifications Maximum values % % (w/w) (w/w).
Free glycerol content Monoglyceride content Diglyceride content Triglyceride content Total glycerol content
0.01 0.28 0.09 <0.01 0.09
0.01 0.31 0.10 <0.01 0.10
0.02 0.8 0.2 0.2 0.25
was >99% w/w complying with the European standard (EN 14 103) that sets a minimum of 96.5% w/w. Also, the methanol content was <0.01% w/w meeting the European standard that sets a maximum of 0.2% w/w. Table 3 shows the composition of biodiesel produced from solvent and press extracted oil. No differences are observed and all values adjust to the European specifications. For comparison purposes the FAMEs of two commonly used feedstocks (e.g. rapeseed and soybean), as well as a promising feedstock (e.g. jatropha) are also included. 3.3. Cetane number The cetane number is one of the most significant properties to specify the ignition quality of a fuel for use in a diesel engine. It is related to the ignition delay time, i.e. the time that passes between injection of the fuel into the cylinder and the onset of ignition [11]. A high cetane number implies better ignition properties. As shown in Table 4, the cetane number for guindilla biodiesel is 59, which complies with international quality standards that prescribe a minimum of 47 (American standard ASTM D 6751) or 51 (European standard EN-14214). It also compares well with biodiesels from other sources, such rapeseed, jatropha and soybean, that have values of 55 [13], 52.3 [12] and 49 [13], respectively. High cetane numbers are associated to esters of saturated fatty acids such as palmitic acid (C16:0) and also to mono-unsaturated compounds such as methyl esters of oleic acids [14]. Thus, the high cetane number of guindilla oil is probably explained by its high content of oleic (63% w/w) and palmitic methyl esters (9.1% w/w). 3.4. Kinematic viscosity Kinematic viscosity is an important fuel property since it affects the operation of fuel injection equipment, particularly at low temperatures when the increase in viscosity affects the fluidity of the fuel. The property is determined at 40 °C and it is known to increase significantly at lower temperatures [15]. Table 4 shows that the kinematic viscosity of biodiesel from guindilla is 4.867 mm2/s. This value complies with biodiesel standards which are 1.9– 6.0 mm2/s in the American standard ASTM D6751 and 3.5– 5.0 mm2/s in the European standard EN-14214. The value obtained in this study is higher than normally obtained for a biodiesel fuel with mostly C16 and C18 FAMEs, e.g. rapeseed has a kinematic viscosity of 4.15–4.76 mm2/s [16]. This may be explained by the presence in guindilla biodiesel of FAMEs with 20 or more carbons (15.3% w/w), as these have higher viscosities than C18 FAMEs [17]. 3.5. Oxidative stability An important technical issue that affects the quality of biodiesel is its susceptibility to oxidation upon exposure to oxygen, light, temperature and the presence of minor contaminants [18]. Oxidative stability is determined by measuring the induction time at 110 °C using a Rancimat method (European standard EN-14112).
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R.S. Martín et al. / Fuel 89 (2010) 3785–3790 Table 3 Properties of guindilla biodiesel. FAMEs w/w %. Method EN 14103. Properties of rapeseed, soybean and jatropha biodiesel is included for comparison.
1
Parameter
Guindilla Solvent extraction
Guindilla Press extraction
Rapeseed1
Soybean1
Jatropha1
C12:0 Lauric acid C14:0 Myristic acid C16:0 Palmitic acid C16:1 Palmitoleic acid C18:0 Stearic acid C18:1 Oleic acid C18:2 Linoleic acid C18:3 Linolenic acid C20:0 Arachidic acid C20:1 Gadoleinic acid C22:0 Behenic acid C22:1 Erucic acid C24:0 Tetracosanic acid C24:1 Tetracosenic acid Other % Unsaturated fatty acids % Saturated fatty acids
<0.1 <0.1 9.2 0.2 3.1 63.1 8.0 0.8 4.6 9.5 0.4 0.8 0.1 <0.1 0.0 82.4 17.4
<0.1 <0.1 9.1 0.1 3.2 63.7 7.7 0.8 4.7 9.3 0.4 0.8 0.1 <0.1 0.0 82.4 17.5
0.0 1.0 3.5 0.0 0.9 64.1 22.5 8.0 0.0 0.0
0.1 0.1 10.2 0.0 3.7 22.8 53.7 8.6 0.0 0.0
0.0 0.1 15.6 0.0 10.5 42.1 30.9 0.2 0.0 0.0
0.0 94.6 5.4
0.8 85.1 14.1
0.6 73.2 23.2
Data from reference [10].
Table 4 Properties of guindilla biodiesel. Press extracted oil. Parameter
Cetane number Oxidative stability at 110 °C Viscosity at 40 °C CFPP Flash point Sulfur content Sulfated ash Acid value Iodine value Phosphorous Content *
Method
EN 15195 EN-14112 EN ISO 3104 EN 116 EN ISO 3679 EN ISO 20884 ISO 3987 EN 14104 EN 14111 EN 14107
Result
59 18.9 4.867 +4 177.0 1.0 <0.01 0.024 79 <0.5
Specification EN-14214
Unit
min.
max.
51 6.0 3.5 – 101 – – – – –
– – 5.0 *
– 10.0 0.02 0.5 120 10.0
h mm2/s °C °C mg/kg % [m/m] mg KOH/g g iodine/100 g mg/kg
Limit determined by each country based on local climate conditions.
The induction time corresponds to the period of time passing before fatty acid methyl esters, aged at 110 °C under a constant air stream, are degraded to such an extent that the formation of volatile acids can be recorded through a conductivity increase [13]. As shown in Table 4 biodiesel from guindilla has an oxidative stability of 18.9 h. This value complies with the European specification that sets a minimum of 6 h using the Rancimat method (EN-14214) and the American standard ASTM D6751 that sets a minimum of 3 h. The oxidative stability of guindilla biodiesel is much higher than biodiesels from other sources. For example, biodiesel derived from jatropha oil has an oxidation stability of 3.95 h in the Rancimat test, needing the addition of antioxidants [19], while rapeseed and soybean have an oxidative stability of 2–1.3 h, respectively [13]. The unusually high oxidative stability of guindilla biodiesel is probably due to its low content (8.8% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3), in relation to rapeseed oil (27.8% w/w), soybean oil (61.3% w/w) [10] and jatropha oil (31.1% w/w) [11]. Polyunsaturated acids have much higher oxidation rates than oleates [5]. Another factor that may help to explain its high oxidative stability is its content of palmitic methyl ester (9.1% w/w content in guindilla oil), that exhibits an oxidative stability >24 h [20].
the methyl esters of which are characterized by a lower crystallization temperature than their vegetable counterparts [22]. To predict the minimum operation temperatures the cold filter plugging point (CFPP) test method was developed (EN-14214). This method defines the temperature at which a fuel jams a filter due to the formation of agglomerates crystals. Each country using EN-14214 can specify certain temperature limits for different times of the year depending on climate conditions [23]. The CFPP is related to the structure of the methyl esters, e.g. saturated methyl esters have higher crystallization temperatures than unsaturated methyl esters and especially polyunsaturated methyl esters. As shown in Table 4, the CFPP of guindilla biodiesel is +4 °C. This value is high in relation to rapeseed biodiesel (CFPP 5 °C, [22]) probably because guindilla biodiesel has a higher content of saturated methyl esters (C16:0, C18:0, C20:0) than rapeseed biodiesel (17.6 vs. 5.4% w/w). The melting points of this FAME are considerably higher than the corresponding mono-unsaturated and especially polyunsaturated FAME. A plausible solution for the of use guindilla biodiesel in cold climate locations is to blend it with low CFPP biodiesels, such as rapeseed biodiesel, or with petrodiesel, as it has been proposed for biodiesel derived from animal fat [22]. 3.7. Other analyzes
3.6. Cold filter plugging point (CFPP) Distillate fuels exhibit operation problems when the temperature drops to 10– 15 °C due to wax settling and plugging of filters [21]. This is also a problem for biodiesels, particularly those derived from animal fats, since they contain less unsaturated acids,
The acid value of guindilla biodiesel was 0.024 mg KOH/g which was consistent with the acid value of the crude oil e.g. 0.06 mg KOH/g [7]. This value is well within the maximum of 0.5 mg KOH/g set in the ASTM and European biodiesel standards. Furthermore, sulfur, sulfated ash and phosphorous contents complied
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with US and European standards. The flash point was 177 °C, complying with the European specification that sets a minimum of 101 °C (EN-14214). 4. Conclusions Biodiesel prepared from guindilla oil exhibited adequate fuel properties such as cetane number, kinematic viscosity and oxidative stability. A relatively high CFPP value (+4 °C) prevents its use unblended in high temperature locations. In relation to recently reported alternative oil sources such as Camelina sativa [10] and Moringa oleifera [4], guindilla biodiesel present a similar potential and should be further explored. A plant improvement program is necessary to increase present oil yields (1000 L/ha), before guindilla oil may be a viable source of biodiesel. This is because 88% of biodiesel production costs are due to the cost of the oil feedstock [24]. References [1] ASTM D 6751-08a. Standard specification for biodiesel fuel (B100) blend stock for distillate fuels. West Conshohocken (PA): ASTM International; 2008. [2] Knothe G. Biodiesel and renewable diesel: a comparison. Prog in Energ Combust 2010;36:364–73. [3] EN-14214. Automotive Fuels – fatty acid methyl esters (FAME) for diesel engines – requirements and test methods. Brussels: Euro Committ for Standardization; 2008. [4] Rashid U, Anwar F, Moser B, Knothe G. Moringa olefera oil: a possible source of biodiesel. Bioresour Technol 2008;99:8175–9. [5] Knothe G, Van Gerpen J, Krahl J. The biodiesel handbook. 1st ed. Champaign: AOCS Press; 2005. [6] Barkley FA. Sapindaceae of Southern South America. Lilloa 1957;28:111–79. [7] Aguilera JM, Fretes A, San Martin R. Characteristics of guindilla (Valenzuela trinervis Bert.) oil. J Am Oil Chem Soc 1986;63:1568–9. [8] Seigler DS, Cortes M, Aguilera JM. Chemical components of guindilla seeds (Valenzuelia trinervis). Biochem Syst Ecol 1987;15:71–3.
[9] AOAC. Official Methods of Analysis. 17th ed. Gaithersburg, Maryland, USA: AOAC International; 2000. [10] Moser BR, Vaughn SF. Evaluation of alkyl esters from Camelina sativa oil as biodiesel and as blend components in ultra low-sulfur diesel fuel. Bioresour Technol 2010;101:646–53. [11] Gopinath A, Puhan S, Nagarajan G. Relating the cetane number of biodiesel fuels to their fatty acid composition: a critical study. Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering 2009;223:565–83. [12] Mohibbe Azam M, Waris A, Nahar NM. Prospects and potential of fatty acid methyl esters of some non-traditional seed oils for use as biodiesel in India. Biomass Bioenerg 2005;29:293–302. [13] Ramos MJ, Fernández CM, Casas A, Rodríguez L, Pérez A. Influence of fatty acid composition of raw materials on biodiesel properties. Bioresour Technol 2009;100:261–8. [14] Knothe G, Matheaus AC, Ryan TW. Cetane numbers of branched and straightchain fatty esters determined in an ignition quality tester. Fuel 2003;82:971–5. [15] Knothe G, Steidley K. Kinematic viscosity of biodiesel components (fatty acid alkyl esters) and related compounds at low temperatures. Fuel 2007;86:2560–7. [16] Rashid U, Anwar F. Production of biodiesel through optimized alkalinecatalyzed transesterification of rapeseed oil. Fuel 2008;87:265–73. [17] Knothe G, Steidley KR. Kinematic viscosity of biodiesel fuel components and related compounds. Influence of compound structure and comparison to petrodiesel fuel components. Fuel 2005;84:1059–65. [18] Knothe G. Some aspects of biodiesel oxidative stability. Fuel Process Technol 2007;88:669–77. [19] Sarin A, Arora R, Singh NP, Sharma M, Malhotra RK. Influence of metal contaminants on oxidation stability of Jatropha biodiesel. Energy 2009;34:1271–5. [20] Knothe G. ‘‘Designer” biodiesel: optimizing fatty acid ester composition to improve fuel properties. Energy Fuel 2008;22:1358–64. [21] Dunn RO, Bagby MO. Low-temperature filterability properties of alternative diesel fuels from vegetable oils. In: Proceeding of the third liquid fuel conference. St Joseph, MI: ASAE; 1996. p. 95–103. [22] Kazancev K, Makareviciene V, Paulauskas V, Janulis P. Cold flow properties of fuel mixtures containing biodiesel derive from animal fatty waste. Eur J Lipid Sci Technol 2006;108:753–8. [23] Knothe G. Analyzing biodiesel: standards and other methods. J Am Oil Chem Soc 2006;9:847–53. [24] Haas MJ, McAloon AJ, Yee WC, Foglia TA. A process model to estimate biodiesel production costs. Bioresour Technol 2006;97:671–8.
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Evaluation of guindilla oil (Guindilia trinervis Gillies ex Hook. et Arn.) for biodiesel production Ricardo San Martín a,*, Teófilo de la Cerda a, Adolfo Uribe a, Paola Basilio a, Miguel Jordán b, Doris Prehn c, Marlene Gebauer c a b c
Pontificia Universidad Católica de Chile, Faculty of Engineering, Department of Chemical and Bioprocess Engineering, Av. Vicuña Mackenna 4860, Santiago, Chile Universidad Mayor, Campus Huechuraba, Camino La Pirámide 5750, Huechuraba, Santiago, Chile Pontificia Universidad Católica de Chile, Faculty of Agronomy, Av. Vicuña Mackenna 4860, Santiago, Chile
a r t i c l e
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Article history: Received 12 January 2010 Received in revised form 10 July 2010 Accepted 14 July 2010 Available online 30 July 2010 Keywords: Biodiesel Guindilla Guindilia trinervis
a b s t r a c t Guindilla plants (Guindilia trinervis Gillies ex Hook. et Arn.) are small shrubs that grow wildly in the mountains of Central Chile in soils and climates not suitable for agriculture. Whole guindilla seeds contain 28–29% w/w oil. Cotyledons represent 45% w/w of the seed and contain 63–64% w/w oil. Main unsaturated fatty acids are oleic (63% w/w), linoleic (8% w/w) and gadoleinic (9.5% w/w), while main saturated fatty acids are palmitic (9.1% w/w) and stearic (3.1% w/w). The content of free fatty acids was 0.06%. Transesterification reactions yielded a biodiesel with ester content >99%; cetane number 59; oxidative stability at 110 °C, 18.9 h; kinematic viscosity at 40 °C, 4.867 mm2/s; cold filter plugging point, CFPP + 4 °C; sulfur content 1.0 mg/kg; sulfated ash < 0.01% p/p; acid value 0.024 mg KOH/g and phosphorous content (<0.5 mg/kg). All values were within European and US specifications. The relatively high CFPP value limits the use of unblended guindilla biodiesel to high temperature weather locations. The high oxidative stability is probably due to the low content (8.8% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3). Guindilla plants grow wildly with estimated yields of 1000 L oil/ha. Plant improvement programs could make these plants a viable alternative for biodiesel production. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Worldwide there is a growing interest on developing alternative energy sources such as biodiesel to overcome high oil costs and future shortage. According to the US standard ASTM D6751 biodiesel is defined as a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats [1]. This fuel is obtained from an oil or fat by a transesterification reaction with glycerol as a by-product [2]. The European biodiesel standard EN-14214 refers to fatty acid methyl esters (FAME) as fuel [3]. Generally, the most abundant vegetable oil in a particular region is the most common feedstock [4]. Thus, in Europe rapeseed and sunflower are predominantly used, palm oil predominates in tropical countries, and soybean and animal fats in the USA [5]. In Chile, the interest on biodiesel production is high since the country depends largely on imported energy resources. Rapeseed is being considered for the production of biodiesel, but its cultivation requires primarily agricultural land. Other high oil yield plants such as Jatropha curcas are being examined, particularly in the
* Corresponding author. Tel.: +56 2 354 4927; fax: +56 2 354 5803. E-mail address: [email protected] (R.S. Martín). 0016-2361/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2010.07.017
Northern semi-arid parts of the country. However, so far, no industrial biodiesel plants have been established in the country. The objective of this project is to evaluate a relatively unknown oil-bearing plant (Guindilia trinervis Gillies ex Hook. et Arn. Sapindaceae, common name guindilla), native of Chile and Argentina, for the production of biodiesel. One of the main advantages of guindilla plants are their ability to survive and thrive in soils and climates regarded unsuitable for agriculture. The genus Guindilia (formerly Valenzuela) is comprised of three species which are restricted to Chile and Argentina [6]. Guindilla is a small shrub that grows abundantly at altitudes over 1500 m, and it is usually covered by snow during the winter. In Chile it is found in the central region of the country, specifically in the mountains of the V, VI, VII and metropolitan regions (Santiago). It is more abundant in sunny areas and flowers between September and November; the fruits mature between December and February. Fig. 1 shows a picture of guindilla plants in their natural habitat. Fig. 2 shows the flowers of guindilla, Fig. 3 the fruits and Fig. 4 the cotyledons. Each adult plant occupies an area of about 1.5 1.5 m. The plant has simple, sessile leaves and a three parted fruit (1–1.5 cm in diameter) in which one or two carpels sometimes abort to make the fruit apparently one seeded [6]. The seed has two cotyledons wrapped inside a seedcoat and contained in a round, thick hull 1–1.5 cm in diameter. Cotyle-
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Fig. 1. Guindilla plants in their natural habitat. Altitude: 1500 m, nearby Santiago, Chile.
pids [8] the research was abandoned. Based on its high oil content and fatty acid composition, the goal of this work is to assess the potential of guindilla oil for the production of biodiesel. 2. Methods 2.1. Guindilla seeds Guindilla seeds were collected from the ground during April, 2008 in the Andes Mountains surrounding the city of Santiago at an altitude of 1511 m. The exact location was characterized as Lagunillas 1, with GPS coordinates: S 33° 37.848´; W 070° 18.601´. The seeds were fractured and manually open to separate the hull and the cotyledons. The seed coat was not removed. The average moisture content of the cotyledons was determined by drying comminuted material at 103 ± 2 °C until constant weight. 2.2. Oil extraction
Fig. 2. Flowers of guindilla.
don cells are filled with oil globules or spherosomes. Guindilla oil composition was studied 25 years ago to evaluate its potential for human consumption [7]. The research indicated that the oil yield of whole seeds (cotyledons plus seed hulls) is about 30% w/ w and that under natural conditions it may be possible to obtain 3.5–4.0 tons of whole seeds/ha or about 1000 L oil/ha. Main fatty acids were 62.3% oleic, 12.9% gadoleic, 10.1% linoleic and 9.6% palmitic [8]. However due to the presence of potentially toxic cyanoli-
Guindilla seeds (cotyledons) were extracted in a continuous laboratory scale screw press (IBG Monforts Oekotec, Model Komet CA59 G, Monchengladbach, Germany). The operating variables were press head temperature (ranging from room temperature to 120 °C), diameter of pellet outlet hole – 0.2, 0.35 and 0.5 cm – and seed feeding rate. Preliminary experiments were performed to maximize oil yields. The most consistent results were obtained at a feeding rate of 1.2 kg seeds/h, press head temperature of 60 °C and a diameter of the pellet outlet hole of 0.5 cm. Lower temperatures reduced oil yields; higher temperatures and lower outlet hole diameters partially burnt the seed cake; higher feeding rates decreased oil yields. Following the first pressing, the resulting seed cake was re-extracted (second pressing). The remaining cake was then placed in a Soxhlet extractor operated with hexane to extract the residual oil. The size of the extractor body was 2 L. For each extraction 900 g of seed cake were contacted with 1.5 L of hexane. Extraction time vs. oil yield was tested at 4, 6 and 8 h. Oil yields at 6 h were 25% higher than at 4 h. Longer extraction times did not improved oil yields. Hence, an extraction time of 6 h was chosen for all experiments. Hexane was removed in a Rotavapor unit with a water bath temperature of 50 °C and 3.07 kPa of vacuum for 1 h.
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Fig. 3. Guindilla seeds in their natural habitat, altitude 1511 m. Lagunillas, Chile.
To remove residual solvent, the oil was sparged at atmospheric pressure with helium for 1 h. 2.3. Oil refining Preliminary experiments considered water degumming followed by acid degumming. Water degumming was performed using 2.5% w/w distilled water, 80 °C and strong mechanical agitation for 40 min. The mixture was then placed overnight in separation funnels. The supernatant was collected and filtered through Whatman 4 to remove remaining insoluble impurities. Acid degumming was performed contacting the oil with 0.2% w/w phosphoric acid (85% w/w), and subjected to a similar procedure than water degumming. Since the impurities removed during acid degumming were negligible, in subsequent experiments this procedure was not used. This is consistent with the low content of phospholipids present in guindilla oil (see Section 3). 2.4. Transesterification reaction The transesterification reaction was performed using methanol and 30% w/w sodium methoxide solution (Na-Metylat, BASF) as
Fig. 4. Guindilla cotyledons.
catalyst. Methanol concentration was based on the saponification index of the oil of 192 [7] and a 5.5:1 M ratio (moles methanol: moles of tri-glycerides). The reaction was performed in a 1 L glass vessel equipped with mechanical agitation and reflux condenser open to atmospheric pressure. The reactor was immersed in a water bath at 80 °C. Each reaction was performed with 180 g of oil, 36 g of methanol and 6 g of 30% w/w sodium methoxide solution. This corresponded to 1.8 g of sodium methoxide and a 1% w/w ratio of sodium methoxide to oil. After 2 h of reaction, the reactor contents were placed in a 1 L glass separation funnel for 15 h at room temperature. The lower phase containing glycerol was discarded. The upper biodiesel phase was collected and washed with water using 2:1 water to biodiesel volumetric ratio. Contacting was performed at 70 °C in a 1 L separation funnel with gentle mixing. The mixture was then settled for 15 min, and the water and biodiesel phases separated. This washing procedure was repeated 3 times.
2.5. Analysis All analyzes were performed following European biodiesel standards at the facilities of the ASG Analytik laboratories (Neusäss, Germany). The amount of free glycerol, mono, di and triglycerides in the biodiesel was determined using EN 14105. 1,2,4-butanetriol was used as the standard for the determination of free glycerol, while 1,2,3,-tricaproylglycerol (tricaprin) was used for the determination of the glycerides (mono-,di- and tri-). Cetane number was determined usingthe standard EN 15195. Oxidative stability at 110 °C using the Rancimat method was obtained using the standard EN-14112. Kinematic viscosity at 40 °C was obtained using standard EN ISO 3104. Flash point was determined using standard EN ISO 3679. Cold filter plugging point (CFPP) was determined using standard EN 116. Sulfur content, sulfated ash, acid value and phosphorous content were determined using standards EN ISO 20884, EN ISO 3987, EN 14104 and EN 14107, respectively. Fatty acid profile of the oil was analyzed using EN 14103 modified so that the samples were methylated before analysis. The free fatty acids and phospholipids content of the oil were determined using AOAC methods [9].
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R.S. Martín et al. / Fuel 89 (2010) 3785–3790 Table 2 Free and total glycerol in guindilla biodiesel. Method EN 14105.
3. Results and discussion 3.1. Oil extraction and composition Cotyledons represent 45% w/w of whole guindilla seeds and the seed hull 55% w/w. The average natural moisture content of the cotyledons was 3.5% w/w. Press extraction oil yields of the cotyledons were 30.5% w/w for the first pressing and 19.1% w/w for the second pressing. Solvent extraction gave an additional 14% w/w. Thus, the overall extraction yield from the cotyledons was 63.6% w/w, which agrees with previous analyzes, e.g. 67% w/w oil [7]. Thus, the average oil yield based on whole seeds (cotyledons and hulls) was 28.6% w/w. The oil extracted with hexane contained 0.6–0.7% phospholipids, while the pressed oil contained 0.1–0.3% phospholipids. These values are low in relation to other feedstocks such as rapeseed and soybean oil. Due to this, the refining process using just water degumming was sufficient. Table 1 shows the fatty acid profile of oil samples obtained by solvent and press extraction. No significant differences in composition are observed. Main unsaturated fatty acids are oleic (63% w/ w), linoleic (8% w/w) and gadoleinic (9.5% w/w), while main saturated fatty acids are palmitic (9.1% w/w) and stearic (3.1% w/w). The overall content of unsaturated and saturated fatty acids are 82.4% and 17.6% w/w, respectively. These results are in close agreement with previous analyzes, e.g.: oleic, 62.3%; gadoleinic 12.5%; linoleic, 10.1%, and palmitic, 9.6% [7]. In relation to other common biodiesel feedstock such as rapeseed oil, guindilla oil contains a similar content of oleic acid (63% w/w), but exhibits a high content (9.5% w/w) of gadoleinic acid (C20:1), as well as arachinic acid (4.6% w/w; C20:0). It also contains low amounts (8.5% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3) in relation to rapeseed oil, e.g. 27.8% w/w [10]. 3.2. Production of biodiesel Average production yields of biodiesel were 85–90% w/w. Soap formation was not observed, in agreement with the low content of free fatty acids in the oil, e.g. 0.06%. These yields are acceptable under laboratory conditions, and can be improved significantly industrially, where more efficient recovery operations can be implemented. Table 2 shows the amount of free glycerol, mono, di and tri-glycerides and total glycerol in the biodiesel. All parameters comply with the European standards and also with US standard ASTM D-6571 that sets a limit for free glycerin of 0.02% and for total glycerin (free and bound) of 0.24%. This indicates that the extent of the transesterification reaction is adequate and that there is no excess of glycerol in the biodiesel. The ester content
Table 1 Fatty acid profile of guindilla oil obtained through solvent and press extraction Analysis method: EN 14103 modified (fatty acids were methylated before analysis). Parameter
Solvent extraction % w/w
Press extraction % w/w
C12:0 Lauric acid C14:0 Myristic acid C16:0 Palmitic acid C16:1 Palmitoleic acid C18:0 Stearic acid C18:1 Oleic acid C18:2 Linoleic acid C18:3 Linolenic acid C20:0 Arachidic acid C20:1 Gadoleinic acid C22:0 Behenic acid C22:1 Erucic acid C24:0 Tetracosanoic acid C24:1 Tetracosenic acid
<0.1 <0.1 9.2 0.1 3.1 62.9 8.0 0.9 4.7 9.7 0.4 0.9 0.1 <0.1
<0.1 <0.1 9.0 0.1 3.2 63.7 7.6 0.8 4.7 9.5 0.4 0.8 0.1 <0.1
Parameter
Solvent extraction % (w/w)
EN-14214–03 Press extraction Specifications Maximum values % % (w/w) (w/w).
Free glycerol content Monoglyceride content Diglyceride content Triglyceride content Total glycerol content
0.01 0.28 0.09 <0.01 0.09
0.01 0.31 0.10 <0.01 0.10
0.02 0.8 0.2 0.2 0.25
was >99% w/w complying with the European standard (EN 14 103) that sets a minimum of 96.5% w/w. Also, the methanol content was <0.01% w/w meeting the European standard that sets a maximum of 0.2% w/w. Table 3 shows the composition of biodiesel produced from solvent and press extracted oil. No differences are observed and all values adjust to the European specifications. For comparison purposes the FAMEs of two commonly used feedstocks (e.g. rapeseed and soybean), as well as a promising feedstock (e.g. jatropha) are also included. 3.3. Cetane number The cetane number is one of the most significant properties to specify the ignition quality of a fuel for use in a diesel engine. It is related to the ignition delay time, i.e. the time that passes between injection of the fuel into the cylinder and the onset of ignition [11]. A high cetane number implies better ignition properties. As shown in Table 4, the cetane number for guindilla biodiesel is 59, which complies with international quality standards that prescribe a minimum of 47 (American standard ASTM D 6751) or 51 (European standard EN-14214). It also compares well with biodiesels from other sources, such rapeseed, jatropha and soybean, that have values of 55 [13], 52.3 [12] and 49 [13], respectively. High cetane numbers are associated to esters of saturated fatty acids such as palmitic acid (C16:0) and also to mono-unsaturated compounds such as methyl esters of oleic acids [14]. Thus, the high cetane number of guindilla oil is probably explained by its high content of oleic (63% w/w) and palmitic methyl esters (9.1% w/w). 3.4. Kinematic viscosity Kinematic viscosity is an important fuel property since it affects the operation of fuel injection equipment, particularly at low temperatures when the increase in viscosity affects the fluidity of the fuel. The property is determined at 40 °C and it is known to increase significantly at lower temperatures [15]. Table 4 shows that the kinematic viscosity of biodiesel from guindilla is 4.867 mm2/s. This value complies with biodiesel standards which are 1.9– 6.0 mm2/s in the American standard ASTM D6751 and 3.5– 5.0 mm2/s in the European standard EN-14214. The value obtained in this study is higher than normally obtained for a biodiesel fuel with mostly C16 and C18 FAMEs, e.g. rapeseed has a kinematic viscosity of 4.15–4.76 mm2/s [16]. This may be explained by the presence in guindilla biodiesel of FAMEs with 20 or more carbons (15.3% w/w), as these have higher viscosities than C18 FAMEs [17]. 3.5. Oxidative stability An important technical issue that affects the quality of biodiesel is its susceptibility to oxidation upon exposure to oxygen, light, temperature and the presence of minor contaminants [18]. Oxidative stability is determined by measuring the induction time at 110 °C using a Rancimat method (European standard EN-14112).
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R.S. Martín et al. / Fuel 89 (2010) 3785–3790 Table 3 Properties of guindilla biodiesel. FAMEs w/w %. Method EN 14103. Properties of rapeseed, soybean and jatropha biodiesel is included for comparison.
1
Parameter
Guindilla Solvent extraction
Guindilla Press extraction
Rapeseed1
Soybean1
Jatropha1
C12:0 Lauric acid C14:0 Myristic acid C16:0 Palmitic acid C16:1 Palmitoleic acid C18:0 Stearic acid C18:1 Oleic acid C18:2 Linoleic acid C18:3 Linolenic acid C20:0 Arachidic acid C20:1 Gadoleinic acid C22:0 Behenic acid C22:1 Erucic acid C24:0 Tetracosanic acid C24:1 Tetracosenic acid Other % Unsaturated fatty acids % Saturated fatty acids
<0.1 <0.1 9.2 0.2 3.1 63.1 8.0 0.8 4.6 9.5 0.4 0.8 0.1 <0.1 0.0 82.4 17.4
<0.1 <0.1 9.1 0.1 3.2 63.7 7.7 0.8 4.7 9.3 0.4 0.8 0.1 <0.1 0.0 82.4 17.5
0.0 1.0 3.5 0.0 0.9 64.1 22.5 8.0 0.0 0.0
0.1 0.1 10.2 0.0 3.7 22.8 53.7 8.6 0.0 0.0
0.0 0.1 15.6 0.0 10.5 42.1 30.9 0.2 0.0 0.0
0.0 94.6 5.4
0.8 85.1 14.1
0.6 73.2 23.2
Data from reference [10].
Table 4 Properties of guindilla biodiesel. Press extracted oil. Parameter
Cetane number Oxidative stability at 110 °C Viscosity at 40 °C CFPP Flash point Sulfur content Sulfated ash Acid value Iodine value Phosphorous Content *
Method
EN 15195 EN-14112 EN ISO 3104 EN 116 EN ISO 3679 EN ISO 20884 ISO 3987 EN 14104 EN 14111 EN 14107
Result
59 18.9 4.867 +4 177.0 1.0 <0.01 0.024 79 <0.5
Specification EN-14214
Unit
min.
max.
51 6.0 3.5 – 101 – – – – –
– – 5.0 *
– 10.0 0.02 0.5 120 10.0
h mm2/s °C °C mg/kg % [m/m] mg KOH/g g iodine/100 g mg/kg
Limit determined by each country based on local climate conditions.
The induction time corresponds to the period of time passing before fatty acid methyl esters, aged at 110 °C under a constant air stream, are degraded to such an extent that the formation of volatile acids can be recorded through a conductivity increase [13]. As shown in Table 4 biodiesel from guindilla has an oxidative stability of 18.9 h. This value complies with the European specification that sets a minimum of 6 h using the Rancimat method (EN-14214) and the American standard ASTM D6751 that sets a minimum of 3 h. The oxidative stability of guindilla biodiesel is much higher than biodiesels from other sources. For example, biodiesel derived from jatropha oil has an oxidation stability of 3.95 h in the Rancimat test, needing the addition of antioxidants [19], while rapeseed and soybean have an oxidative stability of 2–1.3 h, respectively [13]. The unusually high oxidative stability of guindilla biodiesel is probably due to its low content (8.8% w/w) of polyunsaturated acids (e.g. C18:2 + C18:3 + C20:2 + C20:3), in relation to rapeseed oil (27.8% w/w), soybean oil (61.3% w/w) [10] and jatropha oil (31.1% w/w) [11]. Polyunsaturated acids have much higher oxidation rates than oleates [5]. Another factor that may help to explain its high oxidative stability is its content of palmitic methyl ester (9.1% w/w content in guindilla oil), that exhibits an oxidative stability >24 h [20].
the methyl esters of which are characterized by a lower crystallization temperature than their vegetable counterparts [22]. To predict the minimum operation temperatures the cold filter plugging point (CFPP) test method was developed (EN-14214). This method defines the temperature at which a fuel jams a filter due to the formation of agglomerates crystals. Each country using EN-14214 can specify certain temperature limits for different times of the year depending on climate conditions [23]. The CFPP is related to the structure of the methyl esters, e.g. saturated methyl esters have higher crystallization temperatures than unsaturated methyl esters and especially polyunsaturated methyl esters. As shown in Table 4, the CFPP of guindilla biodiesel is +4 °C. This value is high in relation to rapeseed biodiesel (CFPP 5 °C, [22]) probably because guindilla biodiesel has a higher content of saturated methyl esters (C16:0, C18:0, C20:0) than rapeseed biodiesel (17.6 vs. 5.4% w/w). The melting points of this FAME are considerably higher than the corresponding mono-unsaturated and especially polyunsaturated FAME. A plausible solution for the of use guindilla biodiesel in cold climate locations is to blend it with low CFPP biodiesels, such as rapeseed biodiesel, or with petrodiesel, as it has been proposed for biodiesel derived from animal fat [22]. 3.7. Other analyzes
3.6. Cold filter plugging point (CFPP) Distillate fuels exhibit operation problems when the temperature drops to 10– 15 °C due to wax settling and plugging of filters [21]. This is also a problem for biodiesels, particularly those derived from animal fats, since they contain less unsaturated acids,
The acid value of guindilla biodiesel was 0.024 mg KOH/g which was consistent with the acid value of the crude oil e.g. 0.06 mg KOH/g [7]. This value is well within the maximum of 0.5 mg KOH/g set in the ASTM and European biodiesel standards. Furthermore, sulfur, sulfated ash and phosphorous contents complied
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with US and European standards. The flash point was 177 °C, complying with the European specification that sets a minimum of 101 °C (EN-14214). 4. Conclusions Biodiesel prepared from guindilla oil exhibited adequate fuel properties such as cetane number, kinematic viscosity and oxidative stability. A relatively high CFPP value (+4 °C) prevents its use unblended in high temperature locations. In relation to recently reported alternative oil sources such as Camelina sativa [10] and Moringa oleifera [4], guindilla biodiesel present a similar potential and should be further explored. A plant improvement program is necessary to increase present oil yields (1000 L/ha), before guindilla oil may be a viable source of biodiesel. This is because 88% of biodiesel production costs are due to the cost of the oil feedstock [24]. References [1] ASTM D 6751-08a. Standard specification for biodiesel fuel (B100) blend stock for distillate fuels. West Conshohocken (PA): ASTM International; 2008. [2] Knothe G. Biodiesel and renewable diesel: a comparison. Prog in Energ Combust 2010;36:364–73. [3] EN-14214. Automotive Fuels – fatty acid methyl esters (FAME) for diesel engines – requirements and test methods. Brussels: Euro Committ for Standardization; 2008. [4] Rashid U, Anwar F, Moser B, Knothe G. Moringa olefera oil: a possible source of biodiesel. Bioresour Technol 2008;99:8175–9. [5] Knothe G, Van Gerpen J, Krahl J. The biodiesel handbook. 1st ed. Champaign: AOCS Press; 2005. [6] Barkley FA. Sapindaceae of Southern South America. Lilloa 1957;28:111–79. [7] Aguilera JM, Fretes A, San Martin R. Characteristics of guindilla (Valenzuela trinervis Bert.) oil. J Am Oil Chem Soc 1986;63:1568–9. [8] Seigler DS, Cortes M, Aguilera JM. Chemical components of guindilla seeds (Valenzuelia trinervis). Biochem Syst Ecol 1987;15:71–3.
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