The oil content (%) of 4 plants, using mechanical oil extraction and Soxhlet extraction methods.
Biodiesel mainly comes from edible oil, and there is little research on its yield from non-edible sources with low-cost oil. It is paramount to investigate the non-edible oil resources which may lead to advance the commercial feasibility of biodiesel and cost effectiveness as well as resolve the food issues. This chapter describes four novel non-edible seed oil sources comprising Koelreuteria paniculata, Rhus typhina, Acacia farnesiana and Albizzia julibrissin for biodiesel production. We aimed to optimize different reaction parameters for oil extraction, alkali-catalyzed transesterification process for maximal biodiesel production and finally evaluate its compatibility with mineral diesel. The optimization factors in transesterification included the molar ratio of methanol to oil, reaction time, stirring intensity, catalyst concentration and temperature. Two methods have been described including Soxhlet and mechanical for extraction of seed oil. The synthesized esters were evaluated and characterized through the nuclear magnetic resonance (NMR; 1H and 13C), Fourier transform infrared (FT-IR) and gas chromatography–mass spectrometry (GC–MS) and the total conversion of crude oil to fatty acid methyl esters (FAMEs) were established. The inductively coupled plasma-optical emission spectrometry (ICP-OES) and Elemental Analyzer (EA) were used for evaluation of elemental concentration. The physico-chemical characterizations of the biodiesel, i.e., flash point, pour point, cloud point, and density were within the American Society for Testing and Materials (ASTM; D6751) and European Standards ((EN14214). Koelreuteria paniculata produced highest biodiesel oil content by Soxhlet extraction (28–30%) followed by the Albizzia julibrissin (19–24%), Acacia farnesiana (23%), Rhus typhina (20–22%). The density ranged from 0.83–0.87 @ 15°C (g/cm3) and the kinematic viscosity ranged from 3.75–6.3 (mm2/s) among all the plant sources. Koelreuteria paniculata had highest Na (5456.2), Cr (1246.8), Ni (658.36), and Al (346.87) elemental concentrations (μg/g) than other plant sources. The elemental percent of C, H, N, and O of biodiesel ranged from 72.54–76.86, 11.25–13.34, 1.97–2.73, and 9.86–12, respectively. In conclusion, these non-edible plant seeds offer a cheap source of renewable energy and can be easily grown on barren and wastelands and contribute to efficient biodiesel production to mitigate the energy crisis.
- Acacia farnesiana
- Albizzia julibrissin
- Rhus typhina
- Koelreuteria paniculata
The global energy need has been confronting major challenges owing to population growth and industrialization [1, 2]. Green house gases and their emissions as well as developing energy safety mechanisms have perpetually turned the focus on research and technological development in this sector. The researcher community is applying renewable energy practices as an alternate to petroleum fuels with biodiesel, bioethanol, biomass, biogas, and synthetic fuels with the aim to curtail net CO2 emission, and improve air, soil, water and global warming . The American Biodiesel Standard Specification (ASTM 6751) defines biodiesel (also named fatty acid methyl ester; FAMEs) as fuel comprising of monoalkyl esters of long-chain fatty acids acquired from vegetable oils or animal fats . The International Energy Agency (IEA) provided the estimates about global market share of biofuels to be increased from 1% (2004) to 7% by 2030 . The need for utilizing biodiesel is associated with its lower exhaust emissions (COx, SOx) and particulate matter . Moreover, it possesses tremendous biodegradability , lubricity, storage , and higher flash point , oxygen content than diesel [9, 10, 11]. The higher oxygen content reflects the low carbon emissions, particulate emissions, CO, aromatic hydrocarbons, sulfur, smoke, and noise . The major issues for biodiesel production and commercialization from vegetable oils comprise their availability and manufacturing cost .
The raw materials of biodiesel can be classified into three major groups including vegetable oil (edible or non-edible oil), animal fat, and edible waste oil . These sources possess triglycerides  which carry great potential. Biodiesel obtained from vegetable oil has a viable market share in USA and European countries . The scientific community is facing eminent challenge remains for suitable raw materials, their extraction and finally characterization for efficient and cost-effective biodiesel production. The transesterification  is a specialized method for biodiesel production from vegetable sources through conversion of one ester to another having low viscosity than the mineral diesel. The transesterification reaction involves catalyst between triglycerides, and short-chain alcohols, which produce monoesters, branched-chain, and long-chain triglyceride molecules that are further converted into glycerol and monoesters . The three-step reaction forms monoglycerides and diglycerides as intermediates. As methanol contains lower charge, it is efficiently used for commercial production of biodiesel. Potassium hydroxide (KOH) as a predominate role in transesterification reaction . The palm, sunflower, coconut rapeseed, soybean, and flaxseed are some of the raw materials being employed for commercialization . Vegetable oil contains complex structure so it cannot be directly used in diesel engines and it will further aggravate the food supply chain through depletion of forests and wildlife destruction. Thus, impetus, toward non-edible sources, has been shifted for biodiesel production.
Feedstock has greater significance for ample availability of biodiesel . The redeeming traits of non-edible sources include their toxicity, no utility in human food as it contains Erucic acid as major constituent of fatty acid; 56–66% , and its easy cultivation on poor soils , and cost-effectiveness. Moreover, it is very stable and possesses low melting point . Biomass is a major energy source covering almost 10–14% of global need due to its easy combustion, less pollution and lower ash content . However, it has equally low calorific value, thermal efficiency (10 to 15%), and comparatively large volume and transportation issues . Chemically, biomass energy can be converted into liquid and gaseous forms .
Many studies have been conducted to explore the non-edible sources for biodiesel production comprising
2. Description of non-edible plant sources
Four novel and non-edible plant sources have been explored for bio-diesel production comprising
One of the plants,
3. Oil extraction methodologies and outcomes from non-edible plant sources
3.1 Oil extraction
After shelling, drying and pulverizing with a grinder (Xiantaopai XTP-10000A, Zhejiang, China) the seeds were processed for extraction. The oil extraction from
The oil production was calculated by the following equation.
The comparative oil content (%) of 4 plants, obtained by using mechanical oil extraction and Soxhlet extraction methods from four plant sources is given in Table 1.
3.2 Fourier-transform infrared spectroscopy (FT
FT-IR spectroscopy data of the mid-infrared region of biodiesel samples to recognize functional groups and the bands analogous to various stretching and bending vibrations is highlighted in Table 2.
|3||2925||-CH2||Asymmetric stretching vibration||Strong|
|4||2854||-CH2||Symmetric stretching vibration|
|5||1743||-C=O||Shear type vibration||Strong|
|7||1361||-CH3||Symmetric stretching vibration,||Middling|
|10||723||-CH2||Plane rocking vibration||Weak|
3.3 Nuclear magnetic resonance (NMR)
The FAMEs NMR spectrum was acquired by (Bruker Avance III 400 NMR Spectrometer, Karlsruhe, Germany) at 400 MHz (1H-NMR) or 100 MHz (13C-NMR). Denatured chloroform was used as solvent and tetramethylsilane as the internal standard. The biodiesel 1H NMR (300 MHz) spectrum was noted with a cycle delay of 1.0 s, and eight times scans with a pulse duration of 30°, (Table 3). A carbon 13C NMR (75 MHz) spectrum was recorded with pulse duration of 30°and a cycle delay of 1.89 s, followed by scanning for 160 times (Table 4).
|3||0.89||Multiplet||CH3 is attached to aliphatic group.|
|16||1.30||Multiplet||Long aliphatic chain is present.|
|2||1.62||Quartet||CH2 group is attached with terminal CH3.|
|3||2.04||Multiplet||CH2 of long chain aliphatic (Saturated) group.|
|2||2.30||Triplet||CH2 group is attached with CH of long aliphatic (Unsaturated/ olefinic group).|
|1||2.77||Triplet||CH group is attached with electron withdrawing carbonyl group.|
|3||3.66||Singlet||Methoxy(OCH3)group attached with electron withdrawing carbonyl group.|
|3||5.34||Multiplet||Olefinic hydrogen of long chain unsaturated aliphatic group|
|14.07||Terminal methyl carbon||-CH3|
|174.24||Carboxyl carbon of ester||-COOCH3|
3.4 GC–MS procedure
The outcome of biodiesel in our studies was evaluated by GCMS (QP2010SE, Shimadzu, Japan), furnished with a capillary column: PEG-20 M (30 m × 0.32 mm × 1 μm film thickness). Helium gas flow rate 1.2 mL/min; split ratio 40:1; the injector temperature and injection volume were 220°C and 1 uL; Furnace heat up mode was 100°C for 1 min, then from 100°C rises to 210°C at the increase rate of 10°C/min. Sensor heat mode was 210°C, and then for 20 min, the temperature was continuing at 210°C; ion source temperature of 200°C; for electron impact 70 eV ionization mode used; mass range of 35–500 m/z. The FAMEs of all plant sources were identified with the mass spectrometry fragmentation design provided by the GCMS system software, as matched with those stored in the mass spectrometry library NIST14, and their fatty acid identity was further verified by matching with known standards and values [39, 40, 41, 42].
The comparative GC based identified FAMEs major compositions (%) of prepared biodiesel from four non-edible plant sources is given in Table 5.
3.5 ICP-OES procedure for elemental analysis in biodiesel
Inductively Coupled Plasma Spectrometer (Spectro-blue, Germany) and Elemental Analyzer (Vario EL CUBE, Germany) were used for the presence of metals in the biodiesel. For the ICP-OES test, 1 g of oil sample was taken for incinerating. The ashing process involved an increase in the oven temperature to 200°C in one hour; then the heat levels were mainatained upto 500 °C for 2 h, and finally to 800°C for 5 h. The ash was dissolved in 10 mL of 2% HNO3. The prepared sample was used for elements finding and concentration test of the biodiesel.
The account of ICP-OES comparative element concentrations of 4 non edible oil plant species is given in Table 6.
3.6 Elemental analyzer (EA) procedure for elemental analysis
The element analyzer (Vario EL CUBE, Germany) was used to detect the H, N, C and O concentrations of biodiesel obtained from plant sources [39, 40, 41, 42]. About 0.5 mL of biodiesel, 3 mL of concentrated HCl and 1 mL of nitric acid were taken in a tube and kept them at rest for 10–15min, to dissolve the oil in the solution. Fresh reagents can be used for sample preparation. The aqua regia amount was twice than the sample. About 1 mL of prepared solution was taken in a new tube and added deionized water making it up to 5 mL. The technique was repeated for 2–3 times until the sample appeared as clear and vivid and ready for evaluation of C, H, N, and O concentrations.
The comparative account of elemental analysis of biodiesel obtained from 4 non edible oil plant species is given in Table 7.
3.7 Physiochemical properties of biodiesel seed oil from four non edible oil plant species
The comparative account of physiochemical properties of biodiesel seed oil obtained from four non edible oil plant species is given in Table 8.
|Oil contents (wt. %)||—||—||—||28–30||20–22||23||19–24|
|Density @ 15°C (g/cm3)||0.86–0.90||0.86–0.90||0.809||0.879||0.879||0.831||0.842|
|Kinematic viscosity @ 40°C (mm2/s)||3.5–5.0||1.9–6.0||1.3–4.1||6.21||6.3||5.32||3.75|
|Flashpoint (°C)||Min. 120||Min. 130||60–80||147||168||158||160|
|Max. 0.50||Max. 0.5||—||0.07||0.40|
|Saponification value (mg KOH/g−1)||—||—||—||176.4||175.6||174.8||180.4|
(g I2/100 mg)
|Max. 120||Max. 120||—||80.7||85||142.5||118.5|
@ 20 °C
|Cloud point (°C)||—||—||−15–5||2||7||7||9|
|Pour point (°C)||—||—||−2.0||−30||−11||−28||−12|
|Fire point (°C)||—||—||—||198||189||190|
|Cetane number||Min. 51||Min. 47||49.7||51||—||52||58|
|Free fatty acid (%)||—||—||—||0.91||1.0||0.4||0.9|
|Ash content (g/100 g)||—||—||—||0.002||0.3||0.002||0.003|
|Specific gravity @15 (°C)||—||—||—||0.88||0.855||0.831||0.842|
|Cold filter plug point (°C)||Max.19||Max.19||−16||−18||14||−25||3|
|Sulphated ash content (wt.%)||Max.0.02||—||—||0.003||—||—|
|Oxidation stability (110°C, h)||Min. 6||Min. 3||25.8||—||18.3||−1.86||4.71|
The great potential exists for using non-edible seed oil as biodiesel, which has been highlighted in this chapter. The plant sources explored were
Biodiesel can be synthesized from vegetable oils, animal fats or algae oils . The Soxhlet extraction allows the sample to repeatedly bring into contact with fresh portions of extracting materials, hence facilitating the equilibrium. It remains at relatively high temperature and no filtration is required . In the present study,
The biodiesel production largely depends upon the choice of appropriate, cost-effective and environment friendly catalysts  based on the nature of oil which greatly help in transesterification of oil. Density optimization is a vital biodiesel factor having huge impact on fuel quality as well the cost incurred . The density for all plant sources ranged from 0.83–0.87 @ 15°C (g/cm3). The kinematic viscosity ranged from 3.75–6.3 (mm2/s) among all the plant sources. Our results show that densities of all plant sources were within the ASTM (D6751) and (EN14214) standards.
The 1H-NMR procedure is used to evaluate the un-saturation and “residual” fatty acid composition . In our study, the biodiesel 1H NMR (300 MHz) spectrum was noted with a cycle delay of 1.0 s, and eight times scans with a pulse duration of 30°. 13C NMR spectroscopic data represented the chemical shift values matching to various structural features in FAMEs.
The metals such as Cu, Co, Fe, Mn and Ni are known to catalyze oxidative degradation reactions in vegetable oils and biodiesel . The presence of some metals, such as Al, Ca, Cr, Cu, Fe, Mg, Pb, V and Zn, among other, in fuel is undesirable due to their release into the atmosphere upon fuel combustion .
Flash point of fuels is imperative to determine the prerequisites for transportation and storage temperature . The flash point was highest in the biodiesel oil of
The main shortcomings of biodiesel are related to the low-temperature performance and oxidation stability. The oxidation stability (110°C, h) was recorded as 18.3
Metal-containing fuel additives and un-removed catalysts are the major contributors of sulfated ash . The sulphated ash content (%) was not detected in
The physico-chemical characterizations of the biodiesel, i.e., flash point, pour point, cloud point, and density, have been found within the ASTM (D6751) and (EN14214) standards. The values of fuel properties were comparable with mineral diesel. FT
Conflict of interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this chapter.
Inam Ullah Khan prepared the first draft of the chapter based on his published research work and other relevant literature. Syed Aftab Hussain Shah edited, formatted the entire chapter and worked on bibliography.
This is to certify that chapter has adhered to the research ethics.