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Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent
Accepted Manuscript Title: Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent Authors: Santosh Ashok Kadapure, Kiran A, Anant J, Dayanand N, Rahul P, Poonam K PII: DOI: Reference:
S2213-3437(17)30518-3 https://doi.org/10.1016/j.jece.2017.10.018 JECE 1928
To appear in: Received date: Revised date: Accepted date:
16-6-2017 6-10-2017 9-10-2017
Please cite this article as: Santosh Ashok Kadapure, Kiran A, Anant J, Dayanand N, Rahul P, Poonam K, Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent, Journal of Environmental Chemical Engineering https://doi.org/10.1016/j.jece.2017.10.018 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent Santosh Ashok Kadapurea, Kiran Aa , Anant Ja, Dayanand Na, Rahul.Pa , Poonam Kb
a
Department of Chemical Engineering, KLE Dr MSS Shesgiri College of Engineering and Technology, Belagavi, India b
Dept of BBA, Rani Parvati Devi college of science , Arts and Commerce, Belgaum
Abstract: Despite the fragile bio-fuel market of the present day, numerous research works are being carried out all over the globe to discover a viable alternate source to fossil fuels. The present work envisages developing deep eutectic solvent (DES) for maximization of biodiesel yield from Pongamia pinnata (Feed) oil containing high free fatty acid (FFA). In the present work, transesterification reactions for feed oil were carried out with sodium hydroxide (NaOH) as catalyst and with prepared various DES (choline chloride and acetic acid, oxalic acid and urea) in the Salt/Hydrogen bond donor ratio of 1:2.The best yields were found to be around 94.6% for the reactions with methanol in the molar ratio of 6:1 and 1% of NaOH for DES 2 10%) mixture at residence time of 150 min. The same reaction with DES 1 and DES 3 also yielded satisfactory results (yields 11.6 % greater than DES 0 mixture). The quality of biodiesel produced was judged by comparing physico-chemical properties of FAME (viscosity, density, flash point and calorific values) with ASTM standards which was within acceptable limits. The results give clear evidence showing use of DES improves yield of FAME. The findings obtained in this work may provide a scientific basis for the potential
application of DES synthesized from choline chloride and acetic acid, oxalic acid and urea as a co-solvent in purification of FAME. Multivariable statistical correlations were established for predicting fuel properties as a function of operating variables.
Keywords: Pongamia pinnata; Biodiesel; Non-edible oil; Deep eutectic solvent
1. Introduction
Energy is a fundamental prerequisite for each division of monetary improvement in a nation. With the development of human populace and industrialization, demand for energy has been expanding. Basic wellsprings of vitality are petroleum, normal gas and coal from fossil fills. Maximum utilization of vitality has rapidly exhausted non-renewable wellsprings of vitality. Increasing cost of fossil-based fills and potential lack later on have prompted to a noteworthy worry about the vitality security in each nation. For the present crisis biofuel is expected to be one of the options to meet the demand of energy. Moreover, fossil-based fuel boosts the concentrations of CO2 which triggers green gas emissions. Biodiesel, a well documented alternative bio-fuel, is being used in developed as well as developing countries and there is an increased demand. Biodiesel is an alternative renewable and biodegradable fuel with properties similar to that of petro diesel [1].
In India, fossil diesel fuel is consumed for most of the energy requirements like transportation, irrigation, manufacturing, and electricity generation [2]. Biodiesel is an alluring, renewable and biodegradable fuel for diesel vehicles and warming frame
works. Furthermore, the use of fossil-based fuel is not considered environmentally friendly because it boosts the concentration of carbon dioxide (CO2). Biodiesel which can be derived from abundant vegetable oils, animal fats, or microalgae oil by the transesterification process with methanol and catalysts is arguably the most promising non-petroleum-based renewable fuel. Biodiesel has pulled in expanding consideration due to its natural benefits and that it is produced using renewable assets. Inferable from the increments in raw petroleum costs, restricted feedstock of fossil oil and natural concerns, vegetable oils, for example, corn, soybean, sesame oil and palm oil, and creature fats, have pulled in recharged enthusiasm for the creation of biodiesel energizes.
However, developing countries like India cannot afford to use edible oils as feed for biodiesel production. The conversion of edible oils to biodiesel causes negative impact on society, the farm-problem and reduction of food supply lead to economic imbalance. Nonedible is considered as the promising alternate for traditional edible food crops [3]. Hence non-edible oil seed, such as Pongamia (Pongamia pinnata), is explored along with meeting additional criteria of greening the wastelands without compromising the food, fodder security, and improving livelihoods [4]. P. pinnata is an important non-edible minor oil seed tree (Wealth of India, 1965) that grows in semi-arid regions. The oil has been treated as fuel in diesel engines, showing a good thermal efficiency. It is native to the Indian subcontinent.
1.1 State-of-the-art review
Over the past few years many different types of catalyst have been used in transesterification process of feed oil for increasing yield of biodiesel. However, it was noted that addition of catalyst affects the yield of biodiesel. Results by Karmee and Chadha [5] show that the yield of methyl esters from Karanja oil under the optimal condition was 90 % using Solid acid catalysts viz. Hb-Zeolite, Montmorillonite K-10 and ZnO. Whereas, the research work by Dawodu et al. [6] shows that, at catalyst concentration of 0.75% (NaOH), biodiesel yield of 87.80% was achieved for Sesamum indicum oil. In the case of rice bran oil used by Ahmad, et al [7], it can be seen that using NaOH and KOH catalyst a yield of 80% was observed. Gomes et al. [8]. used heterogeneous catalytic process alternate to homogenous catalyst. Use of such catalyst (CaO modified with alkaline and alkaline earth metal catalysts) in transesterification process of feed oil showed yield of 94%. Kamel et al. [9] used activated carbon as a catalyst in the transesterification of two non-edible oils (waste cooking oil and Jatropha oil) with methanol to produce biodiesel. They observed that conversion to biodiesel reached 93% under optimal conditions. Baskar et al., [3] suggested that using nonedible oil eliminates the food competition, problems associated with food versus fuel. Naik et al. [10] examined the production of biodiesel from high FFA Karanja oil. The authors found the acid value to decrease from 41.9 to 3.970 mg KOH/g in1h in acid-catalyzed
esterification. They observed the yield of methyl ester ranged between 96.6% and 97% when produced from oil having 20%, 15% and 5% FFA contents. Jaime et al. [11] reported the use of commercial CaO material which was impregnated with aqueous solution of lithium nitrate. The catalysts were calcined at 575 °C and 800 °C, for 5 h and used for biodiesel production from semi-refined rapeseed oil. Researchers have used different catalyst to increase the purity of FAME. The main problem exists in the separation process i.e glycerine and biodiesel. Recently, there is increasing demand for improving the yield of biodiesel for various feed stocks. As an answer to this call is in use of green and user-friendly deep eutectic solvent as a co-solvent (green solvent) have emerged. DES can be formed by mixing simple quaternary ammonium salts like choline chloride (ChCl) or Phosphonium salts with suitable Hydrogen Bond Donor [HBD] such as metal halides, acids and other donating groups, under mild heating. Upon mixing the components of a solution properly results in the formation of a eutectic solution, which is normally stable at room temperature. These prepared DES are nontoxic, are simple to synthesize, easily mixed, have low reactivity with water, are prepared easily at low cost and DESs are been considered as green non-flammable solvents [12, 13]. Recently, Alhassan et al. [14] investigated the potential of utilizing prepared DES as cosolvent in improving yield of biodiesel. They concluded that DES synthesized from choline chloride and PTSA could effectively produce biodiesel with acceptable fuel quality via single step process. Lee et al. [12] in his work reported that the optimal DES (yield 94.3 %) was prepared from tetrabutyl ammonium chloride and acetic acid (1: 2); the methanol and
palmitic acid sample to DES ratio was 1: 0.5 (v/v). Hayyan et al [13] in his review article reported the DES prepared with choline chloride and glycerine, ethylene glycol, triethylene glycol and urea showed no toxic effect on all of the studied bacteria confirming their benign effects on these bacteria. Gu et al [15] examined the effect of prepared deep eutectic solvent (DES) consisting of choline chloride and glycerol (1:2 M ratio) for transesterification of rapeseed oil to biodiesel catalyzed by sodium hydroxide. This study showed that up to 98% FAME yields could be obtained at optimum conditions of 6.95 methanol/oil molar ratio, 1.34 wt% catalyst concentration and 9.27 wt% DES concentration. Very little work has been studied on the use of various combinations of DES to improve the yield of biodiesel. The present work focused on enhancing the yield of FAME by using DES of various combinations. This study investigates the effect of prepared DES on the process of conversion of crude Pongamia pinnata oil to biodiesel. The process parameters were optimized to obtain better yield of biodiesel. The physical and chemical tests were used to assess the quality of biodiesel produced. 2. Materials and methods
2.1 Materials
Raw Pongamia pinnata oil was obtained from local market and the composition of fatty acid in the Pongamia pinnata oil (fatty acid) was detected using gas chromatograph and mass spectrum (GC–MS). Methanol (purity 99.8%), ethanol (purity 95%), Choline chloride, oxalic
acid, urea and acetic acid were of analytical grade. Before the experimental run, in order to remove foreign matters, the oil was filtered. 2.2 Preparation of Deep Eutectic Solvents. Deep eutectic solvents was produced by heating choline chloride and a hydrogen donor, such as acetic acid and oxalic acid in various ratios at 60oC for 60 min with constant stirring until a homogeneous liquid was formed [17]. Based upon literature review [12, 13, 15, 16], the following compositions of DES was selected (Table 1). 2.3 Acid transesterification for Pongamia pinnata oil. The initial acid value of P. pinnata seed oil (feed oil) used in this work was 16 mgKOH/g. Determination of contact time for acid transesterification of feed oil is essential. In context of the higher value, the oil was first converted to esters by acid catalyzed esterification process. Time of contact was varied between 15 min to 60 min. Optimum time of contact was determined by carrying out the acid transesterification process. A tetraoxosulphate (IV) acid (98%) is used for methyl esterification of FFA. The feed oil was introduced into round bottom flask. Required amount of methanol is added to the acid (1% v/v of oil) in a 250 ml conical flask. The conical flask was inserted into a water bath at 60o C. The prepared mixture was slowly added to the heated oil inside round bottom flask and placed on a magnetic stirrer with heater for the acid transesterification to take place. With continuous stirring heating was continued with varying reaction time [18]. On completion of
the reaction, the mixture was allowed to fall into two layers. The acid value of the oil obtained was measured. 2.4 Base transesterification The base transesterification process of pongamia pinnata oil obtained from acid transesterification (pre-treated oil) and was carried out in a 1000 ml three neck round bottom flask equipped with a reflux condenser and magnetic heating mantle. For testing the superiority of prepared DES, biodiesel was produced with and with without DES (10%) using NaOH as a catalyst (1%) with oil to methanol ratios varied from 4:1 to 11:1 [15]. Catalyst concentration of 1% was kept constant as higher concentration may lead to saponification of triglyceride, forming soaps which will increase viscosity. In addition to this the reaction temperature is also kept constant at 60oC.
Above this boiling temperature it tends to
accelerate the saponification of the glycerides [19]. The main factors affecting the alkali-catalyzed transesterification using DES are:
-
DES proportion.
-
Reaction time.
-
Molar ratio of oil to methanol.
The objective of this research work is to obtain the maximum yield of biodiesel by searching the optimal combination of the listed parameters shown in Table 2. 2.5 Separation of biodiesel from glycerine
.After
the reaction was completed, the reaction mixture settled into a biphasic system. The
upper layer mainly consisted of methyl esters, whereas the bottom part contained a mixture of glycerol, DES, excess methanol and NaOH. The reaction mixture was poured into separating funnel and allowed to settle for 8 hr inside a separating funnel to allow clear separation of biodiesel [17]. The bottom layer which contains glycerol and impurities was drawn off. 2.6 Biodiesel washing and drying The biodiesel was washed with warm distilled water at 50°C and the mixture was shaken vigorously to remove contaminants like soap, and other impurities [21]. From the bottom of separating funnel water was allowed to drain out. This procedure was carried out until the aqueous phase became clear and neutral. After washing, the biodiesel was kept in an oven at 70°C overnight [21]. Biodiesel was dried until it was crystal clear. 2.7 Physicochemical analysis of biodiesel Biodiesel samples were analyzed to ascertain the fuel quality of the final product. The analysis of prepared biodiesel with and without DES includes flash point determination (Cleveland open cup method), viscosity (Saybolt viscometer) [23], density, acid value, saponification value [24] and iodine value [24]. The higher heating value was evaluated by using a model which relates HHV to iodine value (IV) and saponification value (SV) [25] HHV = 49.43 - (0.015 IV) - (0.041 SV)
(1)
Cetane number was calculated by using the correlation [25]
CI = 46.3 + 5458/SV - 0.225 IV
(2)
Cetane number (CN) does not differ much from cetane index. Cetane number was evaluated by using the correlation given below [25] CN = CI - 1.5 to 2.6
(3)
The conversion of FFA in feed oil to methyl ester was calculated according to the formula. Conversion (%) = (1- (AVbio /AVoil) where AVbio is the acid value of biodiesel and AVoil is the acid value of feed oil. [25] 2.8 Calculation of Biodiesel Yield Biodiesel yield (BY) was determined using the following formula [22, 25] = (Weight of biodiesel produced / Weight of oil taken) x 100 % [4] 3. Results and discussion 3.1 Characterization of oil The chemical characterization of the feed oil is done by gas chromatographic analysis and shown in Table 3. Raw oil contains around 94% pure triglyceride esters and rest were free fatty acids. The physical characterization of the feed oil is presented in Table 4. 3.2 Determination of contact time for acid – catalyzed pre-treatment process The acid value of feed oil is 16 mg KOH/g feed oil which is high. The acid value of acidcatalyzed pre-treatment of high FFA Karanja oil is shown in Table 5 and Fig 1. As evident in the graph, the acid value decreases from 16 to 0.4 mg KOH/g feed oil in the time bound of 15 min to 90 min. At 15 min of contact time no separation was obtained due to soap formation.
At 90 min of contact time acid value was lowered to 0.4 mg KOH/g feed oil and clear separation was obtained. Hence the esterification reaction was carried out for 90 min. Subsequently, the alcohol layer was removed from the pre-treated oil before the alkalinecatalyzed transesterification process. 3.3 Effect of molar ratio of oil to methanol
The methanol/oil molar ratio is an important parameter which affects the yield of biodiesel. In order to drive the transesterification toward the formation of FAMEs, we evaluated the influence of the methanol -to-oil molar ratio on the yield of biodiesel. In general, high volume of methanol shifts towards the formation of FAME [27]. But higher dilution ratio greatly effects conversion rate. The reaction yield increased up to molar ratio of 8:1. Optimum molar ratio (with and without DES) was observed to be 6:1(Fig 3). Thereon decrease in yield was noticed (Fig 4 and 5). At molar ratio of 4:1 (Fig 2) lower yield (with and without DES) was obtained since sufficient methoxide ions could not be supplied [17]. The higher ratio (11:1) slows down the nucleophilic reaction between methoxide and triglyceride due to the increase of hydrogen bonding and there by decrease of free methanol molecules in the reaction mixture. At any molar ratio presence of various combination of DES increases the yield significantly. Since FAME is insoluble in DES/methanol mixture due to which direct contact between FAME and catalyst reduces and FAME becomes one single phase. With the aid of DES saponification side reaction is minimized and this help separation and purification process which results in higher yield of biodiesel. On the contrary, in the
absence of DES, both FAME and NaOH are soluble in methanol which may induce saponification which complicates separation and purification step and thereby decreases the FAME yield.
3.4 Effect of reaction time: The reaction time is an important parameter for esterification reactions as prolonged heating can cause the reaction to reverse. The superiority of DES was explored with reaction time ranging from 90 min to 180min to optimize the synthesis. The reaction temperature was fixed to be 600C and molar ratio varied from 4:1 to 11:1. The results were summarized in fig. 2 to 5. After 90 min of stirring at 60o C, low quantity of feed oil was transesterified by MeOH into biodiesel. Similarly, the stirring of reaction mixture was carried out from 90 to 180 min. The conversion rate increases sharply for 120 and 150 min of stirring under different combination of DES but decreased at longer times. The highest yield was 94.6% for DES 1 at molar ratio of 6:1. 3.5 Effect of Deep Eutetic Solvent (DES): In order to investigate the performance of the prepared DES, the DES was classified into four groups, each group comprising of different combination of DES. The main classification details of the DES in each group are provided in Table 1. Fig.1 depicts the comparison of yield for biodiesel production at different molar ratio of methanol to oil for NaOH catalyst and for DES 0, DES 1, DES 2 and DES 3.
The process of transesterification of feed oil with methanol using NaOH as catalyst was carried out using DES (various combinations) as the co-solvent at various conditions. The effectiveness of DES was compared with non-DES biodiesel results. In general, the addition of DES results in the increase of biodiesel yield. The biodiesel yield of DES 0 was 34.2, 61.2, 74 % and 68% at 90,120, 150 and 180 min while in DES 1, DES2 and DES 3 increase up to 11.6% (Fig 2 to 5) was noticed. It is worth noting that the transesterification of feed oil with addition of DES of various combinations showed an increase in yield of FAME with respect to non-DES biodiesel. Presence of DES increases the dissolution of NaOH in solution of DES and methanol due to the ionic nature of DES, producing a higher concentration of CH3O needed for the transesterification. In addition to this, DES can capture the by-product glycerol from solution during the reaction, which shifts the reaction equilibrium to the product side and increases the fame yield [25]. DES 1 and DES 2 showed similar trend. DES3 showed slightly lower yield in comparison with DES 1 and DES 2. These results show that use of DES would enhance yield of biodiesel. The best results were obtained for the combination of DES 2 at contact time of 150 min. However for longer duration decrease in yield was noticed. 3.6 Relationship between yield, molar ratio and contact time
The below equation shows the relationship between yield, molar ratio and contact time
from the present work for DES 2. The multiple linear equation expresses the relationships between yield, molar ratio and time, together with coefficients of determination (R2) derived is given below: α = 0.2 + 0.519 γ + 0.495 β
R2 = 0.82
where α= biodiesel yield, γ = molar ratio β = time, min A high value of coefficient of determination, (R2 = 0.82) indicates good relevance between the data points and regression equation. 3.7 Analysis of various properties of biodiesel
The quality of biodiesel produced is more important for engine part of view and various standards have been specified to check the quality. The suitability of biodiesel produced by using DES was verified using certain physical tests. The physical properties of liquid product produced are illustrated in Table 6. Comparison of the test results is done with ASTM standard values as illustrated in Table 6. Physical properties of liquid product obtained closely match with the ASTM values [28]. Density is a key property of biodiesel [30]. The density of biodiesel obtained using DES was 910kg/m3 which is slightly less than that of diesel. Similarly viscosity is also an important parameter of biodiesel. High viscosity may affect the atomization of fuel upon injection into the combustion chamber. Fuel with low
viscosity will not provide sufficient lubrication in the combustion system while fuel with high viscosity tends to form deposit in the engine. The viscosity of biodiesel obtained by using DES was within the range of ASTM standard as shown in Table 6.The other properties such as flash point, viscosity, cetane number, HHV
and iodine values confirm to the ASTM
standards. The maximum value of acid number as per ASTM standard for pure biodiesel is 0.50 mgKOH/g. The acid numbers for biodiesel produced from WCO and palm oil is 0.4 which is below as per ASTM standard. The GC analysis revealed that biodiesel produced using prepared DES shows content of oleic acid, Pamitic acid, Linoleic and other saturated and unsaturated fatty acids.
4. Conclusion: This study observed the feasibility of DES as a co-solvent in purification of biodiesel. Main conclusions drawn from experimental work as given below: 1. DES for biodiesel production was synthesized using choline chloride and urea, oxalic acid and acetic acid. The effect of DES as a co-solvent in the transesterification process was studied under various operating conditions. 2. DES synthesised from various combinations were found to exert a positive effect on the yield of FAME compared to non-DES. 3. DES 2 synthesized from choline chloride and oxalic acid was observed to give maximum separation in comparison to DES 1 and DES3. The trend for DES 1 and
DES 3 was similar. The maximum yield of biodiesel (94.6%) was obtained using DES 2 on the condition as follows: catalyst 1%, molar ratio 6:1 and reaction time 150 min. 4. The physical and chemical properties of biodiesel produced using DES conform to the available standards. 5. The developed multivariable regression equation for DES 2 can predict the yield of biodiesel as a function of molar ratio and reaction time. 6. We believe that prepared DES can act as an excellent co-solvent for the production of biodiesel from pongamia pinnata oil.
Acknowledgement
The authors would like to thank the management authorities of KLE DR .M.S.Sheshgiri College of Engineering and Technology, Belgaum for their kind support. The authors are grateful to Dr. Basavaraj G. Katageri for giving all the encouragement needed which kept the enthusiasm alive.
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10
Acid value,mgKOH/g
8 6 4 2 0 0
20
-2
y = 0.0025x2 - 0.3771x + 13.813 R² = 0.9987 40 60 80
100
Time,min
Fig 1 Decrease in acid value of feed oil with time
90 80 70
% yield
60 50 40 30 20 10 0 90 min 120 min 150min 180 min
DES 0 34.2 61.2 74 72.4
DES1 39.7 63.1 81.1 80.06
DES2 40.9 63.7 80.4 80.1
DES3 37.2 64.3 78.7 77.3
Fig 2 Effect of time variations on yield of biodiesel for molar ratio 4:1
Chart Title 100 90 80 70
% yield
60 50 40 30 20 10 0 90 min
DES 0 40
DES1 43
DES2 44
DES3 41
120 min
64
68.6
69.7
66.1
150min
84.7
90.2
94.6
87.4
180 min
83.3
90.1
92.3
86.7
Fig 3 Effect of time variations on yield of biodiesel for molar ratio 6:1
100 90 80 70
% yield
60 50 40 30 20 10 0
DES 0
DES1
DES2
DES3
90 min
39
43.3
44.5
40.7
120 min
66
68.1
68.8
65.9
150min
84.1
89.1
91.3
87.5
180 min
83.4
89
89.2
86.4
Fig 4 Effect of time variations on yield of biodiesel for molar ratio 8:1
100 90 80
% yield
70 60 50 40 30 20 10 0
DES 0
DES1
DES2
DES3
90 min
37
41.1
40.9
37.8
120 min
65.2
66.4
67.3
65.7
150 min
81.1
87.5
88.1
86.8
180min
77.1
86.3
87.8
85.3
Fig 5 Effect of time variations on yield of biodiesel for molar ratio 11:1
Table 1 Compositions of the synthesized DES Abbreviation
Salt
Hydrogen bond donor
Salt/Hydrogen bond donor ratio
DES-0
-
-
-
DES-1
Choline chloride
Acetic acid
1:2
DES-2
Choline chloride
Oxalic acid
1:2
DES-3
Choline chloride
Urea
1:2
Table 2 Range of parameters selected
Catalyst %
Temp K
Molar ratio
Reaction time (min)
DES %
363
4-11:1
90 -150
10
NaOH 1
Table 3 Composition of fatty acid in Sesame oil.
Fatty acids
(Wt %)
Palmitic acid
18.11
Srearic acid
7.80
Oleic acid
47.41
Lilonic acid
16.2
Free fatty acid
8-12
Table 4. Physical and chemical parameters of pongamia pinnata oil.
Parameters
Values
Acid value (mgKOH/g)
16
Soponification value
183
Iodine value
91.1
Viscosity (cSt)
11.4
Flash point (oC)
220
Density (Kg/m3)
921
Sp.gravity
0.921
Table 5. Variation of acid value with time Time (Min)
Acid value, mgKOH/g
Separation
0
16
-
15
8.8
Soap formation
30
4.6
No clear separation
45
1.4
Separation obtained
90
0.4
Clear separation
Table 6 Physicochemical analysis of prepared biodiesel compared with standards Parameters
ASTM D6751
Biodiesel
Standard
(DES )
Biodiesel
limit/IS Physical state at 25°C
Liquid
Liquid
Flash point (oC)
>130
210
180
Kinematic Viscosity
1.9 to 6.0
4.1
4.1
Density (kg/m3)
-
910
900
Acid value
0.50 mg
0.4
0.2
Saponification value
276
220
Iodine value (g I2/100 g)
76.2
71.1
Higher heating value
39.26
39.34
48.93
53.6
(mm2/s)
mg KOH/g oil
KOH/g
(MJ/Kg) Cetane number
Min 47
S2213-3437(17)30518-3 https://doi.org/10.1016/j.jece.2017.10.018 JECE 1928
To appear in: Received date: Revised date: Accepted date:
16-6-2017 6-10-2017 9-10-2017
Please cite this article as: Santosh Ashok Kadapure, Kiran A, Anant J, Dayanand N, Rahul P, Poonam K, Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent, Journal of Environmental Chemical Engineering https://doi.org/10.1016/j.jece.2017.10.018 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Optimization of conversion of Pongamia pinnata oil with high FFA to biodiesel using novel deep eutectic solvent Santosh Ashok Kadapurea, Kiran Aa , Anant Ja, Dayanand Na, Rahul.Pa , Poonam Kb
a
Department of Chemical Engineering, KLE Dr MSS Shesgiri College of Engineering and Technology, Belagavi, India b
Dept of BBA, Rani Parvati Devi college of science , Arts and Commerce, Belgaum
Abstract: Despite the fragile bio-fuel market of the present day, numerous research works are being carried out all over the globe to discover a viable alternate source to fossil fuels. The present work envisages developing deep eutectic solvent (DES) for maximization of biodiesel yield from Pongamia pinnata (Feed) oil containing high free fatty acid (FFA). In the present work, transesterification reactions for feed oil were carried out with sodium hydroxide (NaOH) as catalyst and with prepared various DES (choline chloride and acetic acid, oxalic acid and urea) in the Salt/Hydrogen bond donor ratio of 1:2.The best yields were found to be around 94.6% for the reactions with methanol in the molar ratio of 6:1 and 1% of NaOH for DES 2 10%) mixture at residence time of 150 min. The same reaction with DES 1 and DES 3 also yielded satisfactory results (yields 11.6 % greater than DES 0 mixture). The quality of biodiesel produced was judged by comparing physico-chemical properties of FAME (viscosity, density, flash point and calorific values) with ASTM standards which was within acceptable limits. The results give clear evidence showing use of DES improves yield of FAME. The findings obtained in this work may provide a scientific basis for the potential
application of DES synthesized from choline chloride and acetic acid, oxalic acid and urea as a co-solvent in purification of FAME. Multivariable statistical correlations were established for predicting fuel properties as a function of operating variables.
Keywords: Pongamia pinnata; Biodiesel; Non-edible oil; Deep eutectic solvent
1. Introduction
Energy is a fundamental prerequisite for each division of monetary improvement in a nation. With the development of human populace and industrialization, demand for energy has been expanding. Basic wellsprings of vitality are petroleum, normal gas and coal from fossil fills. Maximum utilization of vitality has rapidly exhausted non-renewable wellsprings of vitality. Increasing cost of fossil-based fills and potential lack later on have prompted to a noteworthy worry about the vitality security in each nation. For the present crisis biofuel is expected to be one of the options to meet the demand of energy. Moreover, fossil-based fuel boosts the concentrations of CO2 which triggers green gas emissions. Biodiesel, a well documented alternative bio-fuel, is being used in developed as well as developing countries and there is an increased demand. Biodiesel is an alternative renewable and biodegradable fuel with properties similar to that of petro diesel [1].
In India, fossil diesel fuel is consumed for most of the energy requirements like transportation, irrigation, manufacturing, and electricity generation [2]. Biodiesel is an alluring, renewable and biodegradable fuel for diesel vehicles and warming frame
works. Furthermore, the use of fossil-based fuel is not considered environmentally friendly because it boosts the concentration of carbon dioxide (CO2). Biodiesel which can be derived from abundant vegetable oils, animal fats, or microalgae oil by the transesterification process with methanol and catalysts is arguably the most promising non-petroleum-based renewable fuel. Biodiesel has pulled in expanding consideration due to its natural benefits and that it is produced using renewable assets. Inferable from the increments in raw petroleum costs, restricted feedstock of fossil oil and natural concerns, vegetable oils, for example, corn, soybean, sesame oil and palm oil, and creature fats, have pulled in recharged enthusiasm for the creation of biodiesel energizes.
However, developing countries like India cannot afford to use edible oils as feed for biodiesel production. The conversion of edible oils to biodiesel causes negative impact on society, the farm-problem and reduction of food supply lead to economic imbalance. Nonedible is considered as the promising alternate for traditional edible food crops [3]. Hence non-edible oil seed, such as Pongamia (Pongamia pinnata), is explored along with meeting additional criteria of greening the wastelands without compromising the food, fodder security, and improving livelihoods [4]. P. pinnata is an important non-edible minor oil seed tree (Wealth of India, 1965) that grows in semi-arid regions. The oil has been treated as fuel in diesel engines, showing a good thermal efficiency. It is native to the Indian subcontinent.
1.1 State-of-the-art review
Over the past few years many different types of catalyst have been used in transesterification process of feed oil for increasing yield of biodiesel. However, it was noted that addition of catalyst affects the yield of biodiesel. Results by Karmee and Chadha [5] show that the yield of methyl esters from Karanja oil under the optimal condition was 90 % using Solid acid catalysts viz. Hb-Zeolite, Montmorillonite K-10 and ZnO. Whereas, the research work by Dawodu et al. [6] shows that, at catalyst concentration of 0.75% (NaOH), biodiesel yield of 87.80% was achieved for Sesamum indicum oil. In the case of rice bran oil used by Ahmad, et al [7], it can be seen that using NaOH and KOH catalyst a yield of 80% was observed. Gomes et al. [8]. used heterogeneous catalytic process alternate to homogenous catalyst. Use of such catalyst (CaO modified with alkaline and alkaline earth metal catalysts) in transesterification process of feed oil showed yield of 94%. Kamel et al. [9] used activated carbon as a catalyst in the transesterification of two non-edible oils (waste cooking oil and Jatropha oil) with methanol to produce biodiesel. They observed that conversion to biodiesel reached 93% under optimal conditions. Baskar et al., [3] suggested that using nonedible oil eliminates the food competition, problems associated with food versus fuel. Naik et al. [10] examined the production of biodiesel from high FFA Karanja oil. The authors found the acid value to decrease from 41.9 to 3.970 mg KOH/g in1h in acid-catalyzed
esterification. They observed the yield of methyl ester ranged between 96.6% and 97% when produced from oil having 20%, 15% and 5% FFA contents. Jaime et al. [11] reported the use of commercial CaO material which was impregnated with aqueous solution of lithium nitrate. The catalysts were calcined at 575 °C and 800 °C, for 5 h and used for biodiesel production from semi-refined rapeseed oil. Researchers have used different catalyst to increase the purity of FAME. The main problem exists in the separation process i.e glycerine and biodiesel. Recently, there is increasing demand for improving the yield of biodiesel for various feed stocks. As an answer to this call is in use of green and user-friendly deep eutectic solvent as a co-solvent (green solvent) have emerged. DES can be formed by mixing simple quaternary ammonium salts like choline chloride (ChCl) or Phosphonium salts with suitable Hydrogen Bond Donor [HBD] such as metal halides, acids and other donating groups, under mild heating. Upon mixing the components of a solution properly results in the formation of a eutectic solution, which is normally stable at room temperature. These prepared DES are nontoxic, are simple to synthesize, easily mixed, have low reactivity with water, are prepared easily at low cost and DESs are been considered as green non-flammable solvents [12, 13]. Recently, Alhassan et al. [14] investigated the potential of utilizing prepared DES as cosolvent in improving yield of biodiesel. They concluded that DES synthesized from choline chloride and PTSA could effectively produce biodiesel with acceptable fuel quality via single step process. Lee et al. [12] in his work reported that the optimal DES (yield 94.3 %) was prepared from tetrabutyl ammonium chloride and acetic acid (1: 2); the methanol and
palmitic acid sample to DES ratio was 1: 0.5 (v/v). Hayyan et al [13] in his review article reported the DES prepared with choline chloride and glycerine, ethylene glycol, triethylene glycol and urea showed no toxic effect on all of the studied bacteria confirming their benign effects on these bacteria. Gu et al [15] examined the effect of prepared deep eutectic solvent (DES) consisting of choline chloride and glycerol (1:2 M ratio) for transesterification of rapeseed oil to biodiesel catalyzed by sodium hydroxide. This study showed that up to 98% FAME yields could be obtained at optimum conditions of 6.95 methanol/oil molar ratio, 1.34 wt% catalyst concentration and 9.27 wt% DES concentration. Very little work has been studied on the use of various combinations of DES to improve the yield of biodiesel. The present work focused on enhancing the yield of FAME by using DES of various combinations. This study investigates the effect of prepared DES on the process of conversion of crude Pongamia pinnata oil to biodiesel. The process parameters were optimized to obtain better yield of biodiesel. The physical and chemical tests were used to assess the quality of biodiesel produced. 2. Materials and methods
2.1 Materials
Raw Pongamia pinnata oil was obtained from local market and the composition of fatty acid in the Pongamia pinnata oil (fatty acid) was detected using gas chromatograph and mass spectrum (GC–MS). Methanol (purity 99.8%), ethanol (purity 95%), Choline chloride, oxalic
acid, urea and acetic acid were of analytical grade. Before the experimental run, in order to remove foreign matters, the oil was filtered. 2.2 Preparation of Deep Eutectic Solvents. Deep eutectic solvents was produced by heating choline chloride and a hydrogen donor, such as acetic acid and oxalic acid in various ratios at 60oC for 60 min with constant stirring until a homogeneous liquid was formed [17]. Based upon literature review [12, 13, 15, 16], the following compositions of DES was selected (Table 1). 2.3 Acid transesterification for Pongamia pinnata oil. The initial acid value of P. pinnata seed oil (feed oil) used in this work was 16 mgKOH/g. Determination of contact time for acid transesterification of feed oil is essential. In context of the higher value, the oil was first converted to esters by acid catalyzed esterification process. Time of contact was varied between 15 min to 60 min. Optimum time of contact was determined by carrying out the acid transesterification process. A tetraoxosulphate (IV) acid (98%) is used for methyl esterification of FFA. The feed oil was introduced into round bottom flask. Required amount of methanol is added to the acid (1% v/v of oil) in a 250 ml conical flask. The conical flask was inserted into a water bath at 60o C. The prepared mixture was slowly added to the heated oil inside round bottom flask and placed on a magnetic stirrer with heater for the acid transesterification to take place. With continuous stirring heating was continued with varying reaction time [18]. On completion of
the reaction, the mixture was allowed to fall into two layers. The acid value of the oil obtained was measured. 2.4 Base transesterification The base transesterification process of pongamia pinnata oil obtained from acid transesterification (pre-treated oil) and was carried out in a 1000 ml three neck round bottom flask equipped with a reflux condenser and magnetic heating mantle. For testing the superiority of prepared DES, biodiesel was produced with and with without DES (10%) using NaOH as a catalyst (1%) with oil to methanol ratios varied from 4:1 to 11:1 [15]. Catalyst concentration of 1% was kept constant as higher concentration may lead to saponification of triglyceride, forming soaps which will increase viscosity. In addition to this the reaction temperature is also kept constant at 60oC.
Above this boiling temperature it tends to
accelerate the saponification of the glycerides [19]. The main factors affecting the alkali-catalyzed transesterification using DES are:
-
DES proportion.
-
Reaction time.
-
Molar ratio of oil to methanol.
The objective of this research work is to obtain the maximum yield of biodiesel by searching the optimal combination of the listed parameters shown in Table 2. 2.5 Separation of biodiesel from glycerine
.After
the reaction was completed, the reaction mixture settled into a biphasic system. The
upper layer mainly consisted of methyl esters, whereas the bottom part contained a mixture of glycerol, DES, excess methanol and NaOH. The reaction mixture was poured into separating funnel and allowed to settle for 8 hr inside a separating funnel to allow clear separation of biodiesel [17]. The bottom layer which contains glycerol and impurities was drawn off. 2.6 Biodiesel washing and drying The biodiesel was washed with warm distilled water at 50°C and the mixture was shaken vigorously to remove contaminants like soap, and other impurities [21]. From the bottom of separating funnel water was allowed to drain out. This procedure was carried out until the aqueous phase became clear and neutral. After washing, the biodiesel was kept in an oven at 70°C overnight [21]. Biodiesel was dried until it was crystal clear. 2.7 Physicochemical analysis of biodiesel Biodiesel samples were analyzed to ascertain the fuel quality of the final product. The analysis of prepared biodiesel with and without DES includes flash point determination (Cleveland open cup method), viscosity (Saybolt viscometer) [23], density, acid value, saponification value [24] and iodine value [24]. The higher heating value was evaluated by using a model which relates HHV to iodine value (IV) and saponification value (SV) [25] HHV = 49.43 - (0.015 IV) - (0.041 SV)
(1)
Cetane number was calculated by using the correlation [25]
CI = 46.3 + 5458/SV - 0.225 IV
(2)
Cetane number (CN) does not differ much from cetane index. Cetane number was evaluated by using the correlation given below [25] CN = CI - 1.5 to 2.6
(3)
The conversion of FFA in feed oil to methyl ester was calculated according to the formula. Conversion (%) = (1- (AVbio /AVoil) where AVbio is the acid value of biodiesel and AVoil is the acid value of feed oil. [25] 2.8 Calculation of Biodiesel Yield Biodiesel yield (BY) was determined using the following formula [22, 25] = (Weight of biodiesel produced / Weight of oil taken) x 100 % [4] 3. Results and discussion 3.1 Characterization of oil The chemical characterization of the feed oil is done by gas chromatographic analysis and shown in Table 3. Raw oil contains around 94% pure triglyceride esters and rest were free fatty acids. The physical characterization of the feed oil is presented in Table 4. 3.2 Determination of contact time for acid – catalyzed pre-treatment process The acid value of feed oil is 16 mg KOH/g feed oil which is high. The acid value of acidcatalyzed pre-treatment of high FFA Karanja oil is shown in Table 5 and Fig 1. As evident in the graph, the acid value decreases from 16 to 0.4 mg KOH/g feed oil in the time bound of 15 min to 90 min. At 15 min of contact time no separation was obtained due to soap formation.
At 90 min of contact time acid value was lowered to 0.4 mg KOH/g feed oil and clear separation was obtained. Hence the esterification reaction was carried out for 90 min. Subsequently, the alcohol layer was removed from the pre-treated oil before the alkalinecatalyzed transesterification process. 3.3 Effect of molar ratio of oil to methanol
The methanol/oil molar ratio is an important parameter which affects the yield of biodiesel. In order to drive the transesterification toward the formation of FAMEs, we evaluated the influence of the methanol -to-oil molar ratio on the yield of biodiesel. In general, high volume of methanol shifts towards the formation of FAME [27]. But higher dilution ratio greatly effects conversion rate. The reaction yield increased up to molar ratio of 8:1. Optimum molar ratio (with and without DES) was observed to be 6:1(Fig 3). Thereon decrease in yield was noticed (Fig 4 and 5). At molar ratio of 4:1 (Fig 2) lower yield (with and without DES) was obtained since sufficient methoxide ions could not be supplied [17]. The higher ratio (11:1) slows down the nucleophilic reaction between methoxide and triglyceride due to the increase of hydrogen bonding and there by decrease of free methanol molecules in the reaction mixture. At any molar ratio presence of various combination of DES increases the yield significantly. Since FAME is insoluble in DES/methanol mixture due to which direct contact between FAME and catalyst reduces and FAME becomes one single phase. With the aid of DES saponification side reaction is minimized and this help separation and purification process which results in higher yield of biodiesel. On the contrary, in the
absence of DES, both FAME and NaOH are soluble in methanol which may induce saponification which complicates separation and purification step and thereby decreases the FAME yield.
3.4 Effect of reaction time: The reaction time is an important parameter for esterification reactions as prolonged heating can cause the reaction to reverse. The superiority of DES was explored with reaction time ranging from 90 min to 180min to optimize the synthesis. The reaction temperature was fixed to be 600C and molar ratio varied from 4:1 to 11:1. The results were summarized in fig. 2 to 5. After 90 min of stirring at 60o C, low quantity of feed oil was transesterified by MeOH into biodiesel. Similarly, the stirring of reaction mixture was carried out from 90 to 180 min. The conversion rate increases sharply for 120 and 150 min of stirring under different combination of DES but decreased at longer times. The highest yield was 94.6% for DES 1 at molar ratio of 6:1. 3.5 Effect of Deep Eutetic Solvent (DES): In order to investigate the performance of the prepared DES, the DES was classified into four groups, each group comprising of different combination of DES. The main classification details of the DES in each group are provided in Table 1. Fig.1 depicts the comparison of yield for biodiesel production at different molar ratio of methanol to oil for NaOH catalyst and for DES 0, DES 1, DES 2 and DES 3.
The process of transesterification of feed oil with methanol using NaOH as catalyst was carried out using DES (various combinations) as the co-solvent at various conditions. The effectiveness of DES was compared with non-DES biodiesel results. In general, the addition of DES results in the increase of biodiesel yield. The biodiesel yield of DES 0 was 34.2, 61.2, 74 % and 68% at 90,120, 150 and 180 min while in DES 1, DES2 and DES 3 increase up to 11.6% (Fig 2 to 5) was noticed. It is worth noting that the transesterification of feed oil with addition of DES of various combinations showed an increase in yield of FAME with respect to non-DES biodiesel. Presence of DES increases the dissolution of NaOH in solution of DES and methanol due to the ionic nature of DES, producing a higher concentration of CH3O needed for the transesterification. In addition to this, DES can capture the by-product glycerol from solution during the reaction, which shifts the reaction equilibrium to the product side and increases the fame yield [25]. DES 1 and DES 2 showed similar trend. DES3 showed slightly lower yield in comparison with DES 1 and DES 2. These results show that use of DES would enhance yield of biodiesel. The best results were obtained for the combination of DES 2 at contact time of 150 min. However for longer duration decrease in yield was noticed. 3.6 Relationship between yield, molar ratio and contact time
The below equation shows the relationship between yield, molar ratio and contact time
from the present work for DES 2. The multiple linear equation expresses the relationships between yield, molar ratio and time, together with coefficients of determination (R2) derived is given below: α = 0.2 + 0.519 γ + 0.495 β
R2 = 0.82
where α= biodiesel yield, γ = molar ratio β = time, min A high value of coefficient of determination, (R2 = 0.82) indicates good relevance between the data points and regression equation. 3.7 Analysis of various properties of biodiesel
The quality of biodiesel produced is more important for engine part of view and various standards have been specified to check the quality. The suitability of biodiesel produced by using DES was verified using certain physical tests. The physical properties of liquid product produced are illustrated in Table 6. Comparison of the test results is done with ASTM standard values as illustrated in Table 6. Physical properties of liquid product obtained closely match with the ASTM values [28]. Density is a key property of biodiesel [30]. The density of biodiesel obtained using DES was 910kg/m3 which is slightly less than that of diesel. Similarly viscosity is also an important parameter of biodiesel. High viscosity may affect the atomization of fuel upon injection into the combustion chamber. Fuel with low
viscosity will not provide sufficient lubrication in the combustion system while fuel with high viscosity tends to form deposit in the engine. The viscosity of biodiesel obtained by using DES was within the range of ASTM standard as shown in Table 6.The other properties such as flash point, viscosity, cetane number, HHV
and iodine values confirm to the ASTM
standards. The maximum value of acid number as per ASTM standard for pure biodiesel is 0.50 mgKOH/g. The acid numbers for biodiesel produced from WCO and palm oil is 0.4 which is below as per ASTM standard. The GC analysis revealed that biodiesel produced using prepared DES shows content of oleic acid, Pamitic acid, Linoleic and other saturated and unsaturated fatty acids.
4. Conclusion: This study observed the feasibility of DES as a co-solvent in purification of biodiesel. Main conclusions drawn from experimental work as given below: 1. DES for biodiesel production was synthesized using choline chloride and urea, oxalic acid and acetic acid. The effect of DES as a co-solvent in the transesterification process was studied under various operating conditions. 2. DES synthesised from various combinations were found to exert a positive effect on the yield of FAME compared to non-DES. 3. DES 2 synthesized from choline chloride and oxalic acid was observed to give maximum separation in comparison to DES 1 and DES3. The trend for DES 1 and
DES 3 was similar. The maximum yield of biodiesel (94.6%) was obtained using DES 2 on the condition as follows: catalyst 1%, molar ratio 6:1 and reaction time 150 min. 4. The physical and chemical properties of biodiesel produced using DES conform to the available standards. 5. The developed multivariable regression equation for DES 2 can predict the yield of biodiesel as a function of molar ratio and reaction time. 6. We believe that prepared DES can act as an excellent co-solvent for the production of biodiesel from pongamia pinnata oil.
Acknowledgement
The authors would like to thank the management authorities of KLE DR .M.S.Sheshgiri College of Engineering and Technology, Belgaum for their kind support. The authors are grateful to Dr. Basavaraj G. Katageri for giving all the encouragement needed which kept the enthusiasm alive.
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10
Acid value,mgKOH/g
8 6 4 2 0 0
20
-2
y = 0.0025x2 - 0.3771x + 13.813 R² = 0.9987 40 60 80
100
Time,min
Fig 1 Decrease in acid value of feed oil with time
90 80 70
% yield
60 50 40 30 20 10 0 90 min 120 min 150min 180 min
DES 0 34.2 61.2 74 72.4
DES1 39.7 63.1 81.1 80.06
DES2 40.9 63.7 80.4 80.1
DES3 37.2 64.3 78.7 77.3
Fig 2 Effect of time variations on yield of biodiesel for molar ratio 4:1
Chart Title 100 90 80 70
% yield
60 50 40 30 20 10 0 90 min
DES 0 40
DES1 43
DES2 44
DES3 41
120 min
64
68.6
69.7
66.1
150min
84.7
90.2
94.6
87.4
180 min
83.3
90.1
92.3
86.7
Fig 3 Effect of time variations on yield of biodiesel for molar ratio 6:1
100 90 80 70
% yield
60 50 40 30 20 10 0
DES 0
DES1
DES2
DES3
90 min
39
43.3
44.5
40.7
120 min
66
68.1
68.8
65.9
150min
84.1
89.1
91.3
87.5
180 min
83.4
89
89.2
86.4
Fig 4 Effect of time variations on yield of biodiesel for molar ratio 8:1
100 90 80
% yield
70 60 50 40 30 20 10 0
DES 0
DES1
DES2
DES3
90 min
37
41.1
40.9
37.8
120 min
65.2
66.4
67.3
65.7
150 min
81.1
87.5
88.1
86.8
180min
77.1
86.3
87.8
85.3
Fig 5 Effect of time variations on yield of biodiesel for molar ratio 11:1
Table 1 Compositions of the synthesized DES Abbreviation
Salt
Hydrogen bond donor
Salt/Hydrogen bond donor ratio
DES-0
-
-
-
DES-1
Choline chloride
Acetic acid
1:2
DES-2
Choline chloride
Oxalic acid
1:2
DES-3
Choline chloride
Urea
1:2
Table 2 Range of parameters selected
Catalyst %
Temp K
Molar ratio
Reaction time (min)
DES %
363
4-11:1
90 -150
10
NaOH 1
Table 3 Composition of fatty acid in Sesame oil.
Fatty acids
(Wt %)
Palmitic acid
18.11
Srearic acid
7.80
Oleic acid
47.41
Lilonic acid
16.2
Free fatty acid
8-12
Table 4. Physical and chemical parameters of pongamia pinnata oil.
Parameters
Values
Acid value (mgKOH/g)
16
Soponification value
183
Iodine value
91.1
Viscosity (cSt)
11.4
Flash point (oC)
220
Density (Kg/m3)
921
Sp.gravity
0.921
Table 5. Variation of acid value with time Time (Min)
Acid value, mgKOH/g
Separation
0
16
-
15
8.8
Soap formation
30
4.6
No clear separation
45
1.4
Separation obtained
90
0.4
Clear separation
Table 6 Physicochemical analysis of prepared biodiesel compared with standards Parameters
ASTM D6751
Biodiesel
Standard
(DES )
Biodiesel
limit/IS Physical state at 25°C
Liquid
Liquid
Flash point (oC)
>130
210
180
Kinematic Viscosity
1.9 to 6.0
4.1
4.1
Density (kg/m3)
-
910
900
Acid value
0.50 mg
0.4
0.2
Saponification value
276
220
Iodine value (g I2/100 g)
76.2
71.1
Higher heating value
39.26
39.34
48.93
53.6
(mm2/s)
mg KOH/g oil
KOH/g
(MJ/Kg) Cetane number
Min 47