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Title: Investigation on agro-wastes as a possible source of biodiesel
Authors: Akhtar, Taslim
Keywords: Physical Sciences
Issue Date: 2017
Publisher: University of Sargodha, Sargodha.
Abstract: The presented work was aimed on exploring the possibilities of different agrowaste-materials, as potential feedstocks for the synthesis of biodiesel. Increased mobilization and invention of machines with the rapidly growing industrialization, around the globe, has resulted in proportionate consumption of fossil fuels; resulting in gradual depletion of their reservoirs. This alarming situation prompted the researchers to search for some alternate energy sources, which might be safer, comparably efficient, ecofriendly and preferably renewable. To cope with these parameters, synthesis of biodiesel from non-edible oil sources, preferably from underutilized/ agro-waste materials, got recognition as an emerging field. Biodiesel is reported to be a green fuel in addition to other fuel characteristics, which may possibly replace fossil fuels in future partially or completely. Biodiesel, a first-generation biofuel, has got recognition as a potential alternative of petrodiesel and may be employed without any modification/s in existing compression-ignition engines. Prevailing route for synthesis of biodiesel is transesterification of vegetable oils, extracted from employed feedstock, with short-chain alcohols; either catalytically, catalyzed by an acid, a base or an enzyme or non-catalytically. Biodiesel has number of technical benefits over petrodiesel as it is renewable, non-toxic, biodegradable, and holds comparatively higher oxygen and lower sulphur contents than that of petrodiesel offering reduced emission of different pollutants like particulate matter, carbon monoxide, and sulphur dioxide. Fuel characteristics of biodiesel have been found to be similar or even better in some cases e.g., density, viscosity, flash point, cetane number in comparison to petrodiesel. A number of feedstocks have been successfully explored as potential sources of biodiesel including vegetable oils (e.g., soybean, canola/rapeseed, sunflower, palm, corn, and jatropha), animal fats and yellow grease; of which the vegetable oils have been found to be very promising due to their abundant global availability with significant fuel characteristics. Feedstocks impart major share in the cost of biodiesel production followed by the synthesis and refining procedures. In present work, potential of four indigenous oilseed plants, i.e. china berry (Melia azedarach), Ficus benghalensis, Loquat (Eriobotrya japonica) and Cantaloupe (Cucumis melo var. cantaloupensis), was planned to be evaluated, as viable feedstocks for synthesis of biodiesel. For synthesis of biodiesel, oil from each feedstock was extracted by using n-haxane as extraction medium. Residue of each feedstock was extracted thrice to ensure complete recovery of oil. The oil content (%w/w) was found to be 32 %, 10 %, 24 % and 42.8 %, respectively. Due to lower oil content in F. benghalensis, it was thought to be infeasible and non-potential feedstock for the synthesis of biodiesel. Oil from rest of three feedstocks was subjected to transesterification by conventional alkali-catalyzed method, using NaOH, and yield of biodiesel was found to be 80 %, 94.5 % and 94.54 % for M. azedarach, E. japonica and C. melo var. cantaloupensis, respectively. Due to significantly high biodiesel content in cantaloupe seed oil, transesterification was also carried out by ultrasonic-assisted mode in addition to conventional method i.e., alkali-catalyzed transesterification, using NaOH, and optimization of the process parameters was done using Taguchi method. The parameters selected for optimization include molar ratio of alcohol to oil, amount of catalyst (% w/w of oil) and reaction time (min). The optimum levels for these parameters were methanol to oil ratio of 9:1, catalyst amount of 1 % (w/w) and reaction time of 60 min, respectively. Similarly, the statistical optimization of E. japonica was also carried out using Taguchi method for production parameters, namely molar ratio of alcohol to oil, amount of catalyst, reaction time and temperature. Alcohol to oil molar ratio of 6:1, catalyst amount of 1 % (w/w), 2 h reaction time and 50 °C reaction temperature were found to be the optimum conditions for obtaining 94.52 % biodiesel from this source. Highest contribution was shown by the ‘amount of catalyst’ (67.32 %) followed by molar ratio of alcohol to oil (25.51 %). Fatty acid composition of all the selected feedstocks was determined by GC-FID whereas 1H-NMR and 13C- NMR spectroscopic techniques were used for structure elucidation of the converted triglycerides into methyl esters (FAMEs) as a result of the transesterification of extracted oils. Major fatty acids found in M. azedarach seed oil were oleic acid (69.55 %) and linoleic acid (16.53 %); in E. japonica these were linoleic acid (38.33 %), oleic acid (26.31 %) and linolenic acid (20 %) while in C. melo var. cantaloupensis these were linoleic acid (54.9 %), olieic acid (24.7 %) and palmitic acid (9.88 %). Physicochemical properties, i.e. density (0.878, 0.879 and 0.887g/mL), kinematic viscosity at 40 oC (61.0, 67.2 and 34.5 cSt), refractive index (1.42, 1.44 and 1.48), free fatty acid content (% FFA) (1.0, 1.56 and 0.78 %), iodine value (152.24, 145.69 and 128 I2 g/100 g oil) and saponification value (182.20, 194.28 and 220 mg NaOH/g) of oil extracted from seeds of M. azedarach, E. japonica and C. melo var. cantaloupensis were determined using standard IUPAC methods. Major fuel characteristics of biodiesel obtained from seeds of M. azedarach, E. japonica and C. melo var. cantaloupensis seed oils were determined according to standard ASTM methods. These include cetane number (52.00, 49 and 48.68), flash point (120, 138 and 120 oC ), cloud point (-10, -2 and -3 oC), pour point (-9, -6 and -6 oC), kinematic viscosity (4.7, 4.5 and 3.92 mm2 /s), water % (0.01, 0.0 and 0.01% vol), total ash percentage (zero for all) and distillation range (350, 356 and 340 oC). The obtained values were found to be within ASTM D6751 specifications for biodiesel. Findings of the study reveal viability of all of the opted feedstocks, i.e., M. azedarach, E. japonica and C. melo var. cantaloupensis, to be opted as a viable and prospective option and can be considered for large-scale production of biodiesel as a substitute of petro-diesel.
Gov't Doc #: 21194
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