optimized production of biodiesel by fresh water algae oils...

Indian Journal of Chemical Technology Vol. 26, September 2019, pp. 381-395

Optimized production of biodiesel by fresh water algae oils derived from Chlorella wild stuff and performance characteristics of engine system by employing integration of chemical sciences and engineering technologies

G Panduranga Murthy* & Rajesh Kumar

Engineering Chemistry, Maharaja Institute of Technology, Thandavapura, Nanjanagud Tq., Mysuru District, 571 302, India.

University Department of Chemistry, Ranchi University, Ranchi, 834 001, India.

E-mail:[email protected]

Received 15 March 2019; accepted 22 July 2019

Microalgae have been recognized as most eventual feedstock for biodiesel production owing to its significant lipid contents and they are found to be simple with respect to its cultivation. The imperative factor is that, the algae can extenuating carbon dioxide emission and can mount-up lipids at highest level. The current study has been focussed on production of biodiesel from the freshwater algae, Chlorella vulgaris which is one of the plentiful reserves and explicitly collected from its own natural habitat as wild stuff. The algal material then subjected for processes by employing the integration of bio-engineering technologies, the maximum lipid content is explored from C. vulgaris even it is fully fledged at its natural habitat condition.

The fatty acid profile indicates that, the average polyunsaturated fatty acids (71.6%) and the oil proportion from lipid fractions of C. vulgaris are found to significantly higher as compared to other algal types depicted in the literature. The specific correlation between oils of algae and the vegetable oils reveals that, the algal oil found to be highly viscous, ranging from 10-20 times. Subsequently, the transesterification of the algal oils to its analogous fatty ester is the most promising elucidation to the quandary of high viscosity. The optimum biodiesel yield of 89.65 % is achieved at 70th minute with the formation of 8.6 % glycerol and 2.4% soap, the reaction conditions are simplified and standardized to facilitate a single step extraction from wild culture of C.vulgaris and the quantitative conversion of triglycerides into biodiesel is achieved at the optimum level. In the characterization, the algal diesel show higher Heating value of C. vulgaris (34.5MJ/kg), Gross Calorific value (42.3KJ/Kg), Cetane value (55.56) and the significant out-put is noticed. Further, the parameters on performance and combustion are analyzed with internal combustion (CI) engine system using the different blends of algae esterified oil and petro-diesel at variable loads. The results of AB20 (20% algae oil + 80% pure diesel fuel) blend reveals that, preferred brake thermal efficiency (ηB), brake power (BP), Engine power and higher brake specific fuel consumption (BSFC) are considerably higher due to momentous heating value compared to pure petro-fuel. The enviable characteristics for emissions is recorded for AB20 fuel blend ratio such as, smoke density (SD), lower carbon monoxide (CO), hydrocarbons (HCs) and smoke respectively. Interestingly, the oxides of nitrogen (NOx) emissions are reduced with increasing load as compared to the base engine piston. The results finally show that; AB20 are found to be most promising blend ratio and considerably noteworthy in the naturally grown C. vulgaris with respect to all the parameters. In addition, the exploitation of this algae oil for the existing engine system does not require any modification and hence, this can be a most potential alternative source for biodiesel production for sustainable development.

Keywords: Algae oil, Methyl esters, Algal biodiesel, Chlorella vulgaris-wild culture, IC Engine system, Performance, Emission properties, Sustainable development.

The unconventional fuel has become more attractive in recent times due to the depletion of petroleum fuels, high cost in the current perspective followed by problem with respect to high emissions which leads to environmental degradation1,2. The growing concern regarding the impact of fossil fuel and its radical usage upon the environment and the price of production have led to a detonation in the interest of obtaining energy from various biological resources3-5.

The cohort of 1st and 2nd generation of biomass is often criticized for their high energy requirements and environmental impacts6. Among different biomass categories, algal feedstock (macro and micro-algae) has been identified as a most promising source due its higher photosynthetic efficiency than other groups of biomass7,8. As well, the algal biomass has been considered as 3rd generation biomass towards bio-fuel production which does not require any specified land

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for cultivation but, typically has a high productivity even at its natural habitat and can be converted to a wide variety of energy hauliers9. Besides, algae are a cost-effective choice especially for the production of biodiesel, because of its natural availability and can be cultured in laboratory at low cost10-12. The search is on for exploration of the potential algal biomass directly from their natural habitat as a source of bio-energy feedstock and also considering the cultivation and processing of localized species of algae by applying life cycle assessment (LCA) methodology to achieve algal bio-fuel production systems. Algae as potential source of bio-fuels

Algae have materialized as one of the most potential sources for bio-fuel production and the freshwater algal biomasses are found to be economically viable compared to other bio-resources for the generation of bio-fuels13,14. In order to facilitate sustainable biodiesel production in terms of less input; a suggested approach was using locally available algal feedstock and the species grown-up in their natural habitat is of great interest15,16. The collection of algal biomass directly from the natural environment found to be promising with resistant traits coupled with diversified genetically potential wild factors due to its nutrient sources17-19. Further, the large scale productivity of the algae can be monitored together with the uptake of nutrients and the farming wastes water/effluent will act as a good media for the cultivation of the wild algae in the open system. This will be the most economical approach for significant exploration of algal wild stuff for biodiesel production20. Microalgae: The current perspectives

The Microalgae are infinitesimal in nature and photosynthetic life forms that are found in the environment comprising of both marine and fresh water locations22,23. The microalgae are explicit forms which are efficiently converting radiant energy into potential biomass and the micro-algal fuel has justified with respect to momentous chemical characteristics such as, high calorific value, low density and viscosity respectively. Therefore, the algal biomass has emerged as better feedstock than plant based feedstock to achieve bio-oil-derived biodiesel24,25. In addition, the distinctive characteristic of algae is that; under optimal growth conditions, large quantity of algal biomass are produced, but with comparatively low lipid contents, while species with

high lipid contents are typically slow growing. The major advances in this area can be made through the enticement of lipid biosynthesis through environmental factors26. Consequently, the microalgae can grow rapidly along with sustenance in harsh conditions due to its unicellular nature. Hence, the exploration of microalgae revealed that, it is renewable, eco-friendly and it can contribute in plummeting the CO2 level in the atmosphere which later converts into oil20,27 .

Moreover, the biodiesel from micro-algae is a nontoxic, contains no sulphur and highly biodegradable unconventional fuel that are explored from renewable sources28. Further, the characteristics of biodiesel minimizes the emissions into the environment such as, carbon monoxide (CO), hydrocarbons (HC) and particulate matter (PM) released through the exhaustion gas as compared with petroleum diesel, hence, the algal bio-fuel is eco-friendly apart from its beneficial strategies to the automobile industries29,30. In addition, after generation of bio-fuels; in the stage of oil extraction, the left over residue can be recommended as soil fertilizer or which can be processed in the later part to produce ethanol31,32. In the previous literature, it was found that, the algae are justified as one of the best resources for production of bio-fuels and indeed; other algae are in search of anticipating better feedstock for achieving the highest yield of biodiesel. The promising algae can produce 7 to 31 time’s greater oil than the oil obtained from other oil yielding crops33.

A lot of studies have been carried-out on microalgae biodiesel production followed by its properties, however; the chemical characteristics of algae esterified oils coupled with performance and the emissions of this fuel using diesel engine has not been reported accurately34. Therefore, an attempt has been proposed to accomplish real time protocols through the present research study on the following objectives;

1) To develop etiquette for an alternative, renewable and environmentally friendly fuel (biodiesel) with newer approach from microalgae via sustainable technologies.

2) To use this fuel in the diesel engine especially for industry and agriculture applications.

3) To achieve better engine performance and emission characteristics with the aid of mathematical simulation.

Till now, only few reports are available on Chlorella vulgaris which is explored only under

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controlled culture conditions; but, the sample collected directly from its natural habitat and the biomass of the C. vulgaris for biodiesel production has not been specifically attempted. Therefore, the objective of producing biodiesel at its optimal level is more economical and this study effectively, demonstrates the sustainable production of biodiesel by preliminary techno economic approach under finest reaction conditions. Experimental Section

The algal material of Chlorella vulgaris was successfully collected from a natural stream at ‘Devarayana durga’ which is a specific geographical location in Tumkur district (Karnataka), India. The variability in their growth expressions in the selected algal sample was compared with the same species grown in other parts of southern Karnataka, India. Materials

The chemicals used in the study were of analytical grade procured from the authorized dealers (Merck Co., Mumbai, India). The commercial petro-diesel (Egypt) sample was obtained from an authorized petroleum station for comparative analysis. Taxonavigation of microalgae

Chlorella vulgaris belongs to Chlorophyta (green algae) which is an oxygen-producing, photosynthetic, unicellular or multicellular excluding embryophyte terrestrial plants and lichens; they were subjected for classification by dividing under main taxonomic groups based on their pigmentation. The identification was done by consulting the monographs35-37. Subsequently, the collected algal species were studied under light microscope and identified with the help of standard references. In addition, the quantitative analysis was also made using a plankton-counting cell (Sedgwick rafter) and identification and enumeration of algae were done as per the standard methods36,38. Collection, culture and growth analysis of algae

The micro-algae, Chlorella vulgaris has been selected as the bio-source for biodiesel, which is having high lipid content ranging between 50-60%. It was subjected in the open pond method after collecting from its natural habitat. The culture of C. vulgaris was continuously monitored as per the growth kinetics till 24 days of development and then the biomass was harvested and subjected for drying in the shadow for 4-5 days. Later, the dried material of

C. vulgaris was crushed and powdered and stored in a container for further use37,38. Lipid extraction from micro algae

The biomass of C. vulgaris algae was subjected for drying and ground into homogenous fine powder using suitable mechanical blender. Then, the solvent; N-hexane and Iso-propanol was exercised in the ratio of 1:2 using Soxhlet’s apparatus for the extraction of algae lipid. The algal lipid of about 508 mg was extracted from 1.2 g of C. vulgaris algae wild stuff. Finally, the sample containing algal lipid was maintained in the Rotary evaporator at temperature of 65ºC and then the settled biomass was subjected to centrifugation at 2000 rpm for 10 min in order to separate the lipid form the solvent39.

Algal oils to biodiesel production Biodiesel production was produced by

transesterification process and the reaction was carried out using H2SO4 acid (98%) as a catalyst (100% in relation to the mass of lipid). The methanol was added and the ratio of alcohol/lipid was 30:1 (volume/weight). The half quantity of the methanol volume was previously added in order to dissolve the oil then, the other volume of methanol mixed with H2SO4 and the whole sample. The reaction was executed at 60°C for 4 h. under constant stirring in a water bath using reflux. Finally, the excess alcohol is removed by the evaporation using a rotary evaporator after the complete reaction. The hexane was added to the reaction mixture as a nonpolar solvent. The mixture was transferred to a separating funnel and left to be settled. After settling, the mixture was separated into two distinct phases: an upper hexane layer containing mostly fatty acid methyl ester (FAME) and a bottom layer containing the glycerol and pigments22.

Post-treatment The mixture of both reactant and product was

poured into a separation funnel after completing the entire reaction and the glycerine was settling down at the bottom due to gravity. In the meantime, algal methyl ester (biodiesel) was separated from the top of the funnel and waited until separation appeared not to be proceeding anymore. The glycerine and other impurities were drawn-off at the bottom of the separation funnel. It was washed further with warm water at 60°C temperature in order to remove the soap and other impurities like salt, free fatty acid etc. The process was repeated until raising the biodiesel pH of 6-7 and no soap bubbles appeared on it or the washed


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water became crystal in color. Then, the biodiesel was evaporated with a rotary evaporator to remove dissolved methanol and water. The excess sodium sulfate (Na2SO4) anhydrous was utilized for chemical treatment and finally pure biodiesel was obtained by ultra-filtration40. Transesterification of Algal Oils

The oil extracted from algal biomass was subjected for transesterification process to obtain biodiesel. In this method, 18 mL of methanol, 1.5 gm of potassium hydroxide was added with one litre of algae oil in the reactor. The reaction was conducted for one hour at 60ºC at 110 rpm. Then it was filtered by using Buckner funnel and finally the bottom layer glycerine was separated successfully. The distillation approach was employed to remove solvent and to obtain the clean biodiesel41.

Finally, the algae methyl ester (AME) obtained from Chlorella wild stuff were blended with neat diesel fuel in the ratio of 10% AME with 90% of diesel fuel (AME10) and 20% AME with 80% of diesel fuel (AME20). The important properties of the AME 20 was compared with that of the petro-diesel fuel and listed in Table 1.

The lipid extract was mixed with methanol (1:6 w/v) and KOH/NaOH catalyst (0.6 wt%) for 3 h at 300 rpm. The solution was allowed to settle for phase separation for 16 h. The upper biodiesel layer was separated by a separating funnel, washed three times with water (5% that of ester phase) to remove any traces of methanol, NaOH or glycerol.

The produced biodiesel was then dried over anhydrous sodium sulfate and its yield and that of crude glycerol were determined gravimetrically (Fig. 1A).

The mixture was allowed for the period of 90 min to facilitate the reaction and settle down for 2h in a different funnel to separate the glycerol and biodiesel layer. The upper phase contained biodiesel and lower phase was glycerol. The upper layer was collected and subjected for purification through washing while the lower layer of glycerine was discarded (Fig. 2G).

Analytical calculation of biodiesel yield (%) Biodiesel yield (% w/w) was calculated for

different conditions by using the following formula.

Yield of biodiesel (%) = Weight of the biodiesel produced g

Weight of the algal oil used g 100

Gas chromatography (GC) analysis The GC (Gas chromatography) was employed to

assess the fatty acid methyl ester (FAME). The specification of the GC unit, Agilent 6890 plus, equipped with a HP-50 capillary column (0.53 mm × 30 m, 0.5 lm film) and a flame ionization detector (FID) using pure nitrogen as a carrier gas (4mL/min). The fatty acid esters were accomplished by the chromatography with the help of primed reference mixture of FAME procured from authorized sources42.

Fourier transform infrared (FT-IR) spectroscopy The FT-IR (Fourier transform infrared spectroscopy)

is used to study electric dipole moment of a specific

Table 1 — Preliminary physico-chemical testing of algal oil from natural biomass and biodiesel production

SL. No.

Algae species (Natural

collection)

Appearance Moisture Wt (%)

Temperature (0C)

Weight of algal biomass

(Kg)

Time to reach Max. temp.(hr)

Oil extracted

(Kg)

Optimized production of biodiesel (%)

1. Chlorella vulgaris

Stout and blackish green liquid

0.058 50-70 1.2 2.14 0.610 89.65

Fig. 1A — Transesterification reaction with base KOH/NaOH)catalyst

Fig. 1B — Schematic showing engine testing experimental layout


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molecule to ascertain its IR Spectrum. However, the IR spectra can be accomplished by measuring transmittance, absorbance, photoconductivity and emission respectively. In the study, the IR spectrum of petro-diesel and biodiesel structures was analyzed using FT-IR Perkin-Elmer model (Fig. 3) in the range of 500-4000 cm-1 (Ref.43). Physico–chemical characterization of algal biodiesel

The purified product obtained from oil esterification was subjected for estimating and evaluating its fuel properties by comparing with petro-diesel sample by employing ASTM Standard of analysis for petroleum products. The results were also compared with the petro-diesel oil of European and American standards of biodiesel respectively. The blends of Egyptian petro-diesel with different percent (2%, 5%, 10% and 20%) of the generated biodiesel were prepared on volume basis and their physic-chemical characteristics were also studied. All the

parameters were analyzed in three replicates and the final results were obtained as the mean values44. Cost-effectiveness magnitude of micro-algal oil production at medium scale production

The costs on deliverables will be compared generally by employing different methods. In this study, CEM was applied to evaluate the total process from cultivation, harvest, drying, and oil extraction and conversion by comparing with confidential industrial sources. Development of experimental test rig

The experimental investigation was carried-out using a (Kirloskar TV-I DI diesel engine) test engine was given in Table 2. The specification comprises; a single cylinder provided with 4-stroke water cooled diesel engine with 3.6 kW brake power at constant of 1500 rpm was used in this study. The engine was coupled to an eddy current dynamometer with control systems40.

The produced algal biodiesel and petro-diesel were used to run a CI engine (Table 3 and Fig. 1B) with a

Fig. 2 — (2A) Wild stuff of Chlorella vulgaris.-Natural habitat;(2B) Closer view of C. Vulgaris; (2C) Magnified view of C. Vulgaris;(2D) Microscopic view of C. Vulgaris; (2E) Pre-processing ofC. Vulgaris; (2F) Showing powder of C. Vulgaris; (2G) SeparatingBiodiesel after Processes; (2H) Algal Biodiesel- C. Vulgaris

Fig. 3 — Showing FTIR of biodiesel comparing with petro-diesel


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standard specification was used to check the emissions in the exhaust of the engine. Emission characteristics of the algal biodiesel

The amount of CO, CO2, NOx and unburned Hydrocarbon (HC) was measured at variable engine loads using Automobile Emission analyzer coupled with non-dispersion infrared (NDIR) method. The engine was equipped with crank angle sensor, piezo-type cylinder pressure sensor, thermocouples to measure the temperature of the water, air and exhaust gas. The di-gas analyzer was used to measure the emissions from the exhaust channel. In addition, the smoke meter (AVL) was used to assess the smoke density from the engine exhaust gas45. The schematic view of the experimental setup was shown in the Fig. 1B. A method called Taguchi was employed which is a simplest approach of optimizing experimental parameters in less number of trials. Result and Discussion

Culturing and growth of microalgae The collection of microalgae; Chlorella vulgaris

at its natural habitat was performed productively in the open pond system as per the standard procedure by employing the functional operating conditions comprising of exposure and intensity of light followed

by culture aeration with respect to growth rate of biomass in order to obtain maximum yield of micro-algae which leads to biodiesel at optimum level (Fig. 2A-H).

The collected algal biomass was formed via processing under controlled conditions. The size of the algal slurry with respect to biomass, temperature, Oil extraction via centrifugation, or flocculation followed by suitable solvent systems has been depicted. The production of algal lipid of about 508 g was extracted from 1.2 kg of C. vulgaris algae wild stuff was noted (Table 1). The utilization of residues after extraction of microbial lipid can help improve the economics of algal oil production.

Fatty acid composition The lipids in algae consist of fatty acids between

14 and 18 carbon chain length. The higher intensity of fatty acids was found to be oleic, palmitic, stearic, Linoleic and linolenic acid respectively (Table 4). The similar expressions were also observed in the previous reports24-26. The oils with high oleic and palmitic acids followed by stearic acid content indicate that, the presence of a significant and high-quality of fuel.

The Table 3 shows, properties of biodiesel derived from micro-algae where; the viscosity was found to be increased with increase in fatty acids chain length and degree of saturation. In the combustion chamber, the atomization of fuel was highly affected by viscosity of the bio-diesel and resulted in the formation of deposits23. The presence of saturated and long chain length fatty acids produces a high quality biodiesel with enhanced stability and improved cetane number27,28.

Further, the Fatty Acid Methyl Ester (FAME) profile was found to be remarkable compared to the profile of common fatty acid biodiesels of other algae. The high concentration of saturated FAME declared as excellent oxidation resistance for biodiesel production. The other properties like, Flash point,

Table 2 — Fatty acid composition in wild stuff of C. vulgaris algal biodiesel

SL. No. Fatty acids Structure(FA Chain length) % (w/w)

1. Palmitic acid C16:0 22.84 2. Palmitoleic C16:1 9.81 3. Stearic C18:0 21.85 4. Oleic C18:1 48.53 5. Linoleic C18:2 10.85 6. linolenate C18.3 1.86 7. Myristic acid C14:0 1.12

Table 3 — Properties of biodiesel derived from wild stuff of C. vulgaris algae

SL. No. Property Diesel Algal diesel

1. Viscosity @40ºC in CSt 2.57 4.25 2. Heating value in MJ/kg 46.44 34.5 3. Flash Point inºC 65 113 4. Pour Point in ºC -26 -15 5. Gross calorific value in MJ/kg 45.2 42.3 6. Density@15ºC in gm/cc 0.832 0.862 7. Hydrogen 1.452 1.721 8. Carbon 86.404 89.765 9. Nitrogen 0.281 0.0292 10. Cetane No. -- 55.56

Table 4 — Engine specifications of experimental test rig

SL. No. Engine parameters Specifications

1. Type Kirloskar 2. Number of cylinders Single 3. Cycle Four stroke 4. Cooling Water cooled 5. Cylinder diameter (mm) 85 6. Piston stroke (mm) 110 7. Compression ratio 17:1 8. Rated speed 1500 rpm 9. Maximum output power 6.5 hp


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Pour Point, Calorific value, density followed by cetane number were represented in the Table 5.

Evaluation of physico-chemical properties of algal diesel & their blends

The results on physico-chemical properties in blends of biodiesel-petro-diesel such as density, viscosity, flash point, cetane index and heating values were rationally compared with those of diesel fuel and their blends, AB10 and AB20% with ASTM standards (Table 6). It is apparent that, the viscosity in the blends of algal biodiesel-petro-diesel (AB10 and AB20) was found to be superior to petro-diesel fuel; however, it was analogous with the values of ASTM standards. The more viscous fuel is generally ineffective for use in diesel engines due to incompetent atomization. Hence, the heating values of AB10 and AB20 biodiesel-diesel blends ought to be within the acceptable limit of diesel fuel. The flash point of C. vulgaris biodiesel blend AB10 and AB20 was found to be elevated than diesel fuel and its values were found to be 83, 90 and 73°C, respectively. This makes the algal-biodiesel fuel safer during handling and storage than diesel fuel. In addition, the cetane number of biodiesel blend AB10 and AB20 (56 and 70), respectively were showed higher than the minimum requisite of petro-diesel fuel (69).

FTIR spectrophotometer analysis of biodiesel The main components of diesel are aliphatic

hydrocarbons and their chemical configurations are

analogous to the long carbon chains of the core components of biodiesel. The distinctive absorption bands for the vibrations of C-H, around 2929 and 2850 cm-1 correspondingly parallel to the asymmetric and symmetric vibration modes of methyl groups, were detected.

In the spectra of biodiesel; the FAMEs were found to be as cis-isomers, as to be expected from algal oil for the reason that trans-isomers produce a strong band at 970 cm-1 and a weak band at 3012 cm-1 whereas; cis isomers provide medium nearby 720 cm-1 and 3000 cm-1 bands, which are evident in Fig. 3.

In addition, the biodiesel is mainly comprising of mono-alkyl esters and the strong elongated band of C‚O in methyl ester and O-CH3 showed approximately 1739 cm-1 and 1172 cm-1, correspondingly for algal-diesel which are absent in the spectra of petro-diesel.

Subsequently, in the spectra of biodiesel, the non-existence of a peak higher than 3000 cm-1 corresponding to -OH of carboxylic acid showed a complete transesterification. Whereas, in the spectra of Petro-diesel, the elongated bands of aromatic hydrogen (C-H) and aromatic (C‚C) take place in the region of 2953 cm-1 and 1635 cm-1, respectively, that are absent in biodiesel spectra.

Optimization parameters of biodiesel production

Molar ratio The important parameter for exercising production

of optimum biodiesel is because of the methanol to

Table 5 — Physico-chemical characteristics of algal diesel (C. vulgaris) blends AB10 and AB20 compared to diesel fuel and ASTM standards.

Properties Method ASTM D-6751-02 Standard

Diesel oil Algal diesel blends

(AB10) (AB20)

Density @ 15.56°C ASTM D-4052 0.88 0.8378 0.8405 0.8438 Kinematic viscosity, CST@ 40ºC ASTM D-445 1.9-6.0 1.91 3.31 5.99 Heating value (kJ g−1) ASTM-D975 ------- -------- 41.45 47.75 Flash point, ºC ASTM D-93 >130 73 83 90 Cetane Index ASTM D-976 > 47 68.75 56 69.69 Gross calorific value KJ / Kg ASTM D-224 -------- 44401 42644 40486 Net calorific value KJ / Kg ASTM D-224 ---------- 41670 40017 37866

Table 6 — Emission characteristics in algal biodiesel in comparison with petroleum diesel

SL. No. Fuel Type Emission Characteristics

CO2 (%) CO (%) HC (ppm) NOx (ppm) O2 (%)

1. C. vulgaris 4.115±0.01 0.096±0.004 17.86±0.82 19.44±1.61 17.4±0.02 2. Petro-diesel 4.246±0.00 0.143±0.02 27.66±0.01 22.82±1.71 16.2±0.02

The generated data on Engine with respect to emissions was executed at 3000 rpm for the period of 10 min and the data was recorded for every 60 sec interval. The values were expressed standard deviation (±). The data of emissions expressed in either ppm or % of the total gas content.


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oil molar ratio. In the study, the varied molar ratios were noticed from 4:1 to 8:1 by an interval of two. Initially, the catalyst concentration of 1% KOH was fixed for the reaction conditions to be precise at the temperature, 50°C and 500 rpm mixing intensity for the reaction time of 90 min. The effect of molar ratio on production of biodiesel is represented in Fig. 4. In this, the yield of biodiesel was found to be superior with an increasing molar ratio, whereas, the formation of glycerol and soap was found to be opposite for the generation of biodiesel. When the molar ratio is increased from 4:1 to 6:1, the biodiesel yield is also increased by 18.5%, however there is a decrease in formation of glycerol and soap by 18.5% and 47.55%.

The maximum biodiesel yield (58.4%) was achieved for the molar ratio at 6:1 along with a formation of soap at minimum level. Subsequently, the increase in molar ratio beyond 6:1 facilitated the decreased trend of biodiesel was noticed; interestingly, the formation of soap and glycerol was increased again due to emulsification. The surplus amount of methanol than requisite level can boost-up the solubility of glycerol, which further hampers the separation of biodiesel from the by-products layer. Consequently, the soluble layer of glycerol in the methyl ester phase excites the formation of foam and therefore; apparent loss of biodiesel is observed9. This is in accordance with the10-12 where; the maximum yield (94%) of biodiesel achieved when the reaction condition comprising of methanol to oil molar ratio of 6:1, 1% NaOH, 35°C reaction temperature and 200 rpm of mixing intensity for the reaction time of 66 min.

Catalyst concentration

The effect on concentration of catalyst in the reaction is showed in Fig. 5 where; the catalyst

concentration effect on biodiesel yield was investigated by altering the KOH concentrations of 0.25, 0.5, 1 and 1.5 % wt. The initial unit operational conditions comprising of reaction temperature (50°C), methanol: oil (6:1) ratio and mixing intensity (600 rpm) for 90 min were fixed. The increase in catalyst concentration up to certain level facilitated better yield of biodiesel, beyond that, the yield was decreased. The catalyst concentration of 0.25 % KOH was meagre to complete the reaction; as a result, the yield was very low (42.5%), whereas, the formation of soap was 6.12 %, which was very high. The highest biodiesel yield (63.7%) was achieved at 1.0 % KOH with the formation of 5% glycerol and 2.1 % soap. Subsequently, the increase in KOH concentration of 1.5 %, the yield found to be decreased again to 52% with increase in soap formation. This was due to formation of soap in large quantity facilitated by the saponification process; when high amount KOH was added. As a result, the optimized yield of biodiesel was reduced11. The similar trend for maximum yield of biodiesel of 96% at methanol: oil 6:1, temperature 65°C, 1% KOH and stirring speed 600 rpm from algal samples was observed12. Temperature

The effect of temperature on biodiesel production is revealed in Fig. 6 where, the analysis was carried out at 45, 55, 65 and 75°C with 1 % KOH, 6:1 molar ratio and mixing intensity of 600 rpm for 90 min respectively. The constructive and significant influence over the temperature in the reaction stimulated the conversion of biodiesel at improved level with increase in temperature. The basis behind that combination of oil and methanol increased the solubility of molecules, and hence increased biodiesel production is admitted8.

Fig. 4 — Effect of molar ratio on biodiesel yield

Fig. 5 — Effect of catalyst concentration on biodiesel yield


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Fig. 6 — Effect of reaction temperature on biodiesel yield

The highest yield of biodiesel (81.38%) was recorded at 65°C, but, there was no further improvement in the yield of biodiesel when the temperature is increased. This was due to the decreased level of diffusion and the lower boiling point of methanol (65.7°C) thereby; solubility of solvent reached at saturated level with, which has a tendency to escape from the reactor. In the previous study, similar trends for maximum biodiesel production of 90.6% in rapeseed oil was observed at 65°C with a molar ratio of 6:1 and 1% KOH at 600 rpm stirring rate13. Mixing intensity

The Mixing intensity had a strong influence on production of biodiesel as it has an increased area of interaction between the catalyst and oil containing alcohol. The effect of mixing speed on biodiesel production is systematically represented (Fig. 7). This was due to the inappropriate mixing, the reaction does not occur at the interface between two layers thereby; the yield of biodiesel was decreased13. Subsequently, the effect of mixing intensity on biodiesel production was evaluated with varied stirring speed from 400 to 700 rpm. The initial operation conditions were accomplished at temperature 65°C, methanol: oil 6:1 and 1% KOH for 90 min. The biodiesel yield was found to be increased with increase in mixing intensity due to an increase in the homogenization of the reactants8. The value of biodiesel yield of 60, 70.5, 85 and 84.2% was recorded correspondingly at stirring rate of 400, 500, 600 and 700 rpm. The glycerol formation was 6.4, 7, 9, 6% observed and the soap formation was found to be 3, 2.22, 1.12, 1.9%, respectively. At the increased stirring speed of 500 and 600 rpm, the yield of biodiesel was increased from 60 to 85%. Interestingly, there was no progress in the biodiesel yield with further increase in stirring speed and the maximum yield of biodiesel (85%) at

600 rpm was recorded. This is in accordance with the earlier report14. Reaction time

The maximum biodiesel production was possible with the tangible time needed to facilitate transesterification reaction.

The analysis was carried out at a variable time durations, such as 50, 60, 70 and 80 min with 1% KOH, methanol to oil ratio 6:1 at temperature 65°C and 600 rpm. The biodiesel yield (72 %), glycerine (4.8) % and soap formation was 2.6 % was recorded after completion 50th min (Fig. 8).

The optimum biodiesel yield of 89.65 % was achieved at 70th minute with the formation of 8.6 % glycerol and 2.4% soap. There was no significant enhancement in biodiesel yield due to decrease in diffusion rate; followed by further increase in reaction time beyond 70 min. Analysis of diesel and biodiesel

The fundamental analysis of biodiesel obtained at maximum yield condition is systematically furnished. The biodiesel and its blends have higher viscosity than diesel fuel. The Higher calorific value (HCV) of

Fig. 7 — Effect of mixing intensity on biodiesel yield

Fig. 8 — Effect of reaction time on biodiesel yield


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the Biodiesel, AB10, AB20 and Petro-diesel was 42644.43, 44486.13, and 44401.51 KJ/kg was noticed. The Cetane number of the biodiesel and its blends was relatively superior to diesel fuel. The acid value of the biodiesel was higher than diesel fuel. Similarly, the biodiesel has higher carbon content (69.61 % wt.) and oxygen content (21.66% wt.). The higher oxygen content of biodiesel is apparently attractive for the production of bio-fuel at optimum level. In addition, the moisture and carbon residue content was 0.05 % and 0.048 %wt., respectively was observed. Finally, the measured biodiesel and diesel properties were found within ASTM standard limits (Table 5). CEM for algal biodiesel at medium scale production

In the study, the CEM scheme stands on the estimation that, the dry biomass productivity was 1 ton over a period of one year at medium scale production at controlled condition. However, in the current approach, the biomass of microalgae as wild stuff has been explored from its natural habitat; hence the outcome was found to be techno-economically feasible (Table 7). Engine performance parameters

The experiment was conducted in the single cylinder four stroke water diesel engine systems. The experiment was conducted with neat diesel fuel and with algae oil 20% (AB20) with various injection pressures such as 210 bar, 220 bar and 230 bar respectively. The parameters are enunciated hereunder.

Brake thermal efficiency The characteristics curve of the brake power

against brake thermal efficiency has been represented in the Fig. 9.

It is noticed that, almost all the parameter are lies with the same trend but, there is a slight increase in the brake thermal efficiency for AB20 with 210 bar injection pressure up to part load. The 20% of algae fuel along with the detarded injection pressure increases the brake thermal efficiency. Engine power

The algal oil found to be lower with respect to engine power compared to petro diesel, which may be

Table 7 — Cost-effectiveness magnitude (CEM) of micro-algal oil production at medium scale production

SL. No. Parameter *Value in ₹ Outline in the present study

1. Cost of Algal biomass And other contents 30,000/1T (By In vitro Lab culture)

₹10000/1T [Collection cost] (Biomass explored from natural habitat as Algae wild stuff)

2. Price for 1kg biomass (commercial) 155.25 Nil

3. Price for 1kg oil (commercial) 299.46 Nil

4. Price for 1L oil (commercial) 269.10 Nil

5. Oil recovery 720 L/T 508L/T

6. CO2 mitigation fractional --

7. Residue use for biogas/fertilizer Significant --

8. By-product/co-product need to be produced --

9. Chemicals for extraction 2000.00 ₹2000.00

10. Electricity (Pumps, centrifuges, driers, etc.) 1000.00 ₹1000.00

11. Maintenance (Annual) 3000.00 ₹2500.00 Total Cost 36,723.81 ₹15,500.00

*From confidential industrial sources

Fig. 9 — Brake power v/s brake thermal efficiency at variableinjection pressure


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due to the lower heating value of the algal diesel when it is subjected alone. The algal diesel subjected in association with blending of petro-diesel to the experimental engine and then the engine power was monitored radically (Fig. 10). Brake specific fuel consumption

The algal biodiesel demonstrated significantly higher brake specific fuel consumption (BSFC) at low loads (10%), while at higher loads; this difference is null (Fig. 11).

The increase in the volume of injected fuel demanding to retain power out-put thereby, the BSFC is increased in algal oil compared to petro-diesel. In addition, the decrease in fuel atomization and vaporization which leads to enhanced BSFC due to higher kinematic viscosity and density of fuel. Moreover, there was a temperature rise at 10% engine load, which causes a lean combustion mixture, thus it can elicit even higher fuel consumption in the tested fuels containing low energy as compared to the fuels with higher heating values. In contrast, the higher oxygen content of algal oil compared to petro-diesel facilitates the complete combustion of the fuel that leads to reduced BSFC at higher loads, in which there

was rise with respect to higher temperature compared to low loads. Smoke density

The brake power against smoke was observed that, the algal diesel with standard pressure demonstrates the lesser smoke density in contrast to other parameters.

All other parameters almost are positioned on the same trend (Fig. 12).

Carbon monoxide

The analysis on brake power against carbon monoxide showed that, the decrease of carbon monoxide emission at lower loads. Whereas, the load increases; the amount of carbon monoxide emission also increases.

Fig. 10 — Engine power at variable loads

Fig. 11 — Brake thermal fuel consumption (BSFC) at variable loads

Fig. 11 — Brake thermal fuel consumption (BSFC) at variable loads

Fig. 12 — Brake power against smoke density at variable injection pressure


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Interestingly, the reduced injection pressure leads less carbon monoxide emission in both neat diesel fuel and algae fuel was observed and the same was compared to the detarded and standard injection pressure (Fig. 13). Hydrocarbon

The assessment on variation of the hydrocarbon emission with brake power for both diesel fuel and algae fuel with various injection pressures was made. The reduced hydrocarbon content was observed as compare to standard injection pressure of neat diesel fuel and algal diesel. All other parameters show reduced hydrocarbon emission and especially AB20 with standard injection pressure showed the maximum reduction in the hydrocarbon emission (Fig. 14). Oxides of nitrogen

The emission on oxides of nitrogen for the retarded injection pressure of 210 bars in both neat diesel fuel and AB20 showed the maximum reduction compare to all other parameters (Fig. 15).

Algae are one of the most promising bio-resources which are available in wide range of geographical locations with its typical and explicit climatic features. The diesel derived from algal oil called Algae Fatty Acid Methyl Ester (AFME) is found to be a renewable, low CO2-footprint replacement for petroleum-derived diesel. The mass production of biodiesel is being done today is obtained from vegetable oil including non-edible oil seed crops. Hence, the studies were carried-out extensively on the

functional properties of biodiesel derived from biomasses of different category to determine the potential to replace petroleum diesel3,13,16.

Therefore, the algal fuel quality and combustion efficiency was found to be higher than that of diesel fuel. It could be assessed that, the fuel properties of C. vulgaris biodiesel is found to be promising and almost within the acceptable recommended limits was observed47. Later, the produced biodiesel from wild culture of C. vulgaris oil at AB20 blend was analyzed for kinematic viscosity of 5.99 mm2/s, flash point of 90°C and cetane number of 70 and compared with ASTM standards (Table 5). In all, the biodiesel and its blends were comparatively higher than diesel fuel48,49.

Fig. 13 — Brake power against carbon monoxide emission atvariable injection pressure

Fig. 14 — Brake power against hydrocarbon emission at variable injection pressure

Fig. 15 — Brake power against NOx at variable injection pressure


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On other side, the practical evaluation may leads to difference in power output either higher or lower that is coupled with other conditional factors. For instance, in the study, the analysis on Brake specific fuel consumption (BSFC), which is a measuring tool with respect to the tempo of fuel consumption for every power output. The BSFC was found to be increased in biodiesel as compared to petro-diesel. This observation can be interrelated with the oxygen content of the fuel and more over, the biodiesel are composed of only a few diverse compounds and consequently their properties are largely influenced by the fatty acid composition of the fuel, which is evidently identical to that of feedstock oil (tryglyceride from vegetable/biomass). This has been apparently justified through physical properties comprising of viscosity, density, heating value, cetane number and melting temperature etc. Later, the physical properties of the fuel can influence sequentially relating to the exhaust emissions and performance of the engine.

The FTIR spectra clearly indicated that, the differences in both spectra of the range from 1000 cm-1 to 1300 cm-1, the different peaks of biodiesel were overlapped, which are not present in diesel oil. The absorption peak around 1200 cm-1 was noticed which may be dole out to the asymmetric axial stretching vibrations of C (C‚O)-O bonds of the esters, whereas; peaks around 1183 cm-1 that may be consigned to the asymmetric axial stretching vibrations of O-C-C bonds43.

Generally, the biodiesel obtained from plant seed oils are exhibiting potential benefits as a reliable substitute for gasoline. Interestingly, the biodiesel produced from microbial derived oils especially, algal oils gaining large attention with respect to its habitual diversity in all geographical locations that leads to the possibility of exploring oils along with considerable yields throughout the year. In addition, the fatty acid composition in the plant based esterified oils are similar to one another. These analogous expressions principally include C16 and C18 fatty acids with varying degrees of unsaturation. However, the oils form micro-algae can differ significantly which may contain exceptional fatty acids that are diverge in both chain length and structure50,51. The selected physical properties of the micro-algae fuel was within the ASTM standard.

Further, the biodiesel derived from the micro-alga C. vulgaris, contains a substantial amount of C16:0

(palmitic) methyl ester; C18:1(Stearic acid) methyl ester; C18:1 (Oleic acid) methyl ester; C18:3 Linolenate) metyl ester and C14:0 (myristic) methyl ester, which are rarely found in vegetable oils. The presence of both fatty acids has been shown to be beneficial to biodiesel fuels by improving oxidative stability without sacrificing cold flow performance in the case of palmitoleic acid and improved NOx emissions in the case of shorter chain fatty acids such as myristic acid11.

Nevertheless, the presence of potential fatty acid composition in the obtained esterified oils can have influence relating to the overall performance of a biodiesel fuel. Besides, it is imperative to determine the physical properties of the biodiesel from the selected algal types towards evaluating their effectiveness using a dynamometer coupled to a diesel engine. The higher oxygen content of the biodiesel with respect to fossil fuels was immensely accountable which further contributes to lesser energy density and higher BSFC. Subsequently, the heating value for each unit mass of each biodiesel fuel was found to lower than that of gasoline fuel52.

As expected, due to presence of higher oxygen content in the bio-fuels, the BSFC of biodiesel fuel was found to be significantly higher than that of petro-diesel. The BSFC curve for each biodiesel fuel was similarly shaped and no clear difference is apparent among the four biodiesel fuels tested.

Further, the biodiesel has been shown to reduce many emissions, including CO and unburned hydrocarbons (HC). It has been generally noticed that, the biodiesel has a significant controlled hold with respect to emission parameters. The emission of CO2 was increased for algal diesel fuels with respect to petro-diesel indicating improved combustion due to the presence of oxygen content in the biodiesel. In addition, the emissions of CO were significantly reduced by more than half for the algal biodiesel fuels compared to petroleum diesel. The Hydrocarbon emissions were also found to be reduced substantially in both algal biodiesel fuel compared to petro-diesel. The captivating factor was observed that, the NOx emissions for algae biodiesel were considerably lower than petro-diesel3,15,40,52.

The previous studies have shown that, the esterified oils derived from algal sources have lower NOx emissions compared to other class of bio-fuel oils. The low occurrence of polyunsaturated fatty acids and the predominance of shorter chain length fatty acids


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present in C. vulgaris oil probably may contribute to its low NOx emissions45,53. Conclusion

In the study, the data on performance of algal biodiesel indicates that, the biodiesel derived from algae oils can be most efficient fuels to replace both petroleum diesel followed by biodiesel produced from other vegetable oils. The newer approach in the study was that, the culture of Chlorella vulgaris explored directly from its natural habitat for the production of biodiesel and the efficiency was found to generate similar amounts of power and engine competence when compared to petro-diesel. The parameters like, BSFC BTE, Engine power was found to be most significant with the Algal biodiesel. The reduction of Hydrocarbon and CO emissions in algae diesel was noticed which leads to optimized performance with respect to energy out-put. The NOx emissions are also controlled when compared to petro-diesel and the generated NOx emissions that were significantly lower from the algal diesel. Further, this study demonstrates that micro-algae derived biodiesel shows comparable properties with respect to parameters analyzed. The wide scale use of micro-algae oils as a source for biodiesel in future will require advances in large scale cultivation, exploitation at its natural habitat and optimized processing followed by oil extraction to achieve sustainable biodiesel production.

However, in the current study, the biodiesel from wild culture algae collected directly from its natural habitat is found to be sustainable source of oil for the production of biodiesel and preferred as one of the most potential sources. In the later part of experimental investigations, the engine test rig coupled with single cylinder four stroke diesel engine fuelled by neat algae fuel (AB20) and diesel fuel with various injection pressures such as 210 bars, 220 bar and 230 bar respectively generates the following promising outcomes.

The brake thermal for AB20 at 210 bars showed the slight increase compare to that of diesel fuel and all other parameters.

The diesel fuel with standard injection pressure shows lesser smoke density compare to all other parameters.

The carbon monoxide for neat diesel fuel and AB20 shows the maximum reduction compare to all other parameters.

The set injection pressure with AB20 showed the considerable reduction in the hydrocarbon emission.

The oxides of nitrogen emission for neat diesel and AB20 with injection pressure of 210 bars shown the maximum reduction compare to that of all other parameters.

On the whole, it has been concluded that, the algae oil of Chlorella vulgaris (AB20) blend can be recommended as an alternative potential bio-fuel in diesel engine. The change in the injection pressure 210 bar shows the considerable change in the performance as well as emission characteristics.

Eventually, the CEM was found to be most significant strategy for exploring sustainable production of algal biodiesel as the biomass is proposed to explore from its natural habitat. Acknowledgement

The author thanks the authorities of Ranchi University, Ranchi (Jharkhand State), INDIA for providing this opportunity to explore the significant outcomes through research programme. The author expresses sincere thanks to the Research Supervisor, Dr. Rajesh Kumar, Professor of Chemistry, University department of Chemistry, Ranchi University, Ranchi (Jharkhand State), India for his guidance, counsel and encouragement to carry-out the present research study. References 1 Alberto J, Costa V & de Morais M G, Bioresource Technol,

102 (2011) 3. 2 Amin S, Energy Conver Manage, 50 (2009)1834. 3 Basha S A, Gopal K R & Jebaraj S, Renew Sust Energy Rev,

13 (2009) 1628. 4 Daming H & Haining Z, Energy Procedia, 16(2012)1874. 5 Hoekman S K, Broch A, Robbins C, Ceniceros E &

Natarajan M, Renew Sustain Energy Rev, 16 (2012)143. 6 Turkenburg W C., Renewable energy technologies. In:

Goldemberg, J. (Ed). World Energy Assessment, Preface. United Nations Development Programme, New York, USA, pp: 219-272, Am J Biochem Biotech., 4 (2008) 250.

7 Balat M, Energy Convers Manag, 52 (2011) 1479. 8 Anne S P, Harman-Wave E, et al., Renew Energy, 60 (2013)

625. 9 Al-lwayzy S H, Yusaf T & Al-Juboori R A, Energies,

7 (2014)1829. 10 Ayhan D & Fatih D, Energy Convers Manag, 52 (2011) 163. 11 Arief Widjaja, Makara, Teknologi, 13 (2009) 47. 12 Bajhaiya A K, Mandotra K, Suseela S, Kiran Toppo M R &

Ranade S, Asian j Exp Biol Sci, 1 (2010) 728. 13 Campbell, Guelph Engineering J, 1 (2008) 2.


395

14 Chisti Y, Biotechnol adv, 25 (2007) 294. 15 Demirbas A, Appl Energy, 88 (2011) 3541. 16 Demirbas A & Demirbas M F, Energy Convers Manag,

52 (2011)163. 17 Goldemberg J, World Energy Assessment, Preface, (United

Nations- New York, NY, USA) (2000). 18 Gouveia L & Oliveira A C, J Ind Microbiol Biotechnol,

36 (2009) 269. 19 Gouveia L., et al., Springer Briefs in Microbiology, (2006). 20 Hossain S A, Nasrulhaq A, Chowdhury P & Naqiudden M.,

Am J Biochem Biotechnol, (2008) 250. 21 Jones C S & Mayfieldt S P, Current Opin Biotechnol,

23 (2012) 346. 22 Mata T M, Martins A A & Caetano N S, Renew Sust Energy

Rev, 14 (2010) 217. 23 Miao X Q & Wu Q, Bioresources Technol, 97 (2006) 841. 24 Nagaraj Y P, et al., Int J Curr Microbiol App Sci, 3 (2014). 25 Nagarajan S, Chou S K, Cao S Y, Wu C & Zhou Z,

Bioresource Technol, 145 (2012) 150. 26 Prabakaran P, Ravindran A D, J Biochem Technol,

4 (2009) 469. 27 Sawayama S, Inoue S, Dote Y & Yokoyama S Y,

Energy Convers Manage, 36 (1995) 729. 28 Shailendra Kumar Singh, Ajay Bansal et al., Indian J Chem

Technol, 20 (2013) 341. 29 Sharif A B, Salleh A, Nasrulhaq A, Chowdhury P &

Naqiudden M, Am J Biochem Biotechnol, 4 (2008) 250. 30 Singh J & Gu S, Renew Sust Energy Rev, 14 (2010) 2596. 31 Spolaore P, Joannis-Cassan Duran E & Isambert A,

J Bioscience Bioengg, 101 (2006) 87. 32 Thomas F R, Permaculture Activist, 59 (2006) 1. 33 Topare N S, Renge V C, Khedkar S V, Chavan Y P &

Bhagat S L, Chem Environ Pharm Res, 2 (2011)116. 34 Unpaprom Y, Tipnee S & Rameshprabu R, Inter J Sust

Green Energy , 4 (2015) 15. 35 Philipose M T, Chlorococcales, (ICAR Publication,

New Delhi) 1967.

36 Prescott G W, Algae of the Western Great Lakes area. Otto. Kaetz, (Science Publishers, W. Germany) 1998, pp.977.

37 Agarker M S, Goswami H K, Kaushik S, Mishra S M, Bajpai A K & Sharma U S: Bionature, 14 (1994) 250.

38 Hosmani S P, The Ecoscan, 4 (2010) 53. 39 Axelsson M & Gentili F, PLoS ONE 9(2): (2014)

e89643 40 Avinash K A & Atul D, J Automobile Eng, Proceedings of

I MechE, Part-D, 224 (2009) 73. 41 Ahmed F, Khan A U & Yasar A, African J Environ Sci

Technol, 7 (2009) 358. 42 D’Oca M M G, Viêgas C V, Lemões J S, Miyasaki E K,

Morón-Villarreyes J A, Primel E G & Abreub P C, Biomass Bioenergy, 35 (2011)1533.

43 Robert Milton Silverstein & Francis X, Webster, Spectrometric identification of organic compounds, (Wiley, 1998; the University of Michigan) 2 Sep 2010, p 482

44 Pankaj Kumar, Suseela M R & Kiran Toppo, Asian J Exp Biol Sci, 2 (2011) 493.

45 Halim R, Gladman B, Danquah M K & Webley P A, Bio-resource Technol. 102 (2011) 178.

46 Hellier P & Ladommatos N, Proc Inst Mech Eng Part A J Power Energy, 229 (2015) 714.

47 Velappan R, Sivaprakasam S & Kannan M, Int Res Jr Engg Tech, 2 (2015).

48 Ahmed A S, Khan S Hamdan S, Rahman R, Kalam A, Masjuki H H & Mahlia T M, J Energy Environ, 2 (2010) 1.

49 Hu Q, Sommerfeld M, Harvis E, Ghirardi M, Posewitz M, et al., The Plant J, 54 (2008) 621.

50 Knothe G, Energy Environ Sci, 2 (2009) 759. 51 Tuccar G & Aydin K, Fuel, 112 (2013) 203. 52 Widjaja, A, Chien, C-C & Ju, Y-H, J Taiwan Inst Chemical

Engineers, 40 (2009) 13. 53 Patel J S, Kumar N, Deep A, Sharma A & Gupta D,

SAE Technical Paper, (2014)1378,. 54 Varghese T, Raj J, Raja E & Thamotharan C, Inter J Eng

Adv Technol (IJEAT), 4 (2015) 28.

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