الفهرس 
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Abstract
The need of energy consumption is increasing continuously due to increases in industrialization and population. Accompanied by fossil fuel depletion, has led to a search for alternate biofuel sources. The basic sources of fossil fuels are petroleum, natural gas, and coal. Moreover, biodiesel is a non-toxic and biodegradable with low pollutant. However, the use of micro algae can be a suitable alternative as a potential source of the future renewable bioenergy. Micro algae are sunlight-driven cell factories that convert carbon dioxide to potential biofuels, foods, feeds and high-value bioactives. The idea of using micro algae as a source of fuel is not new, but it is now being taken seriously because of the increasing price of petroleum fuel, more significantly, the emerging concern about global warming that is associated with burning fossil fuels. The objective of this study was to enhance and accelerate the ability of the marine micro alga D. Salina for the production of biodiesel with high quantitative and qualitative value using different a biotic stress factors for the over production of lipid.
The following is a summary of the main experimental results obtained:
1-Effect of different concentration of NaCl (salinity) on growth parameters and lipid % of D. salina:
Different concentrations of NaCl (1.25 (control), 1.75 , 2.25 and 3.0 M/L) were tested to obtain the optimum concentration which gave the highest growth rate and the highest lipid content. The results indicate that 2.25M NaCl is asuitable concentration for the growth and lipid production rather than its corresponding control(1.25M) .This mean that there was direct relation between the growth and lipid content under stress condition. So, increasing salinity resulted in noticeable increase in the growth of D.salina with subsequent increase in the total lipid content.
2-Effect of different pH on growth parameters and lipid % of D. Salina:
In this experiment, D.salina was grown at different pH from (pH=7 to pH=9) pH=7.5 represent control. The growth rate of D. Salina was gradually increased with increasing pH. Results showed that the optimum pH which gave the highest growth rate and highest lipid content was (pH=8.5). Meaning that increasing pH resultd in noticeable increase in the growth with subsequent increase in the total lipid content or alkaline pH stress led to TAG accumulation. The previous increases were significantly when compared with their corresponding control.
3-Effect of different concentration of magensium chloride on growth parameters and lipid % of D. Salina:
Different concentrations of magnesium chloride (0.5, 1.0, 1.5(control) and 2 g /L) were tested to determine the optimum concentration for growth and lipid content. Results indicated that 0.5g magnesium chloride was considered the optimum concentration which gave the highest growth rate and also gave the maximum lipid content. So, increasing magnesium inhibited the growth productivity with subsequent decrease the lipid content.
4-Effect of different nitrogen sources on growth parameters and lipid % of D. Salina:
Nitrogen sources in the form of nitrate ,urea and ammonia were tested in order to determine what is the best N-sources for D. salina. Results indicated that D. salina prefered nitrogen (in the form of nitrate) to give maximum growth rate and also maximum lipid content. So, nitrogen (in the form of nitrate) not only induced microalgae growth but also the lipids accumulation.
5-Effect of depreviation of sodium nitrate (g) on growth parameters and lipid % of Dunaliella salin:
Sodium nitrate was found to be the best nitrogen source supporting relatively higher biomass and lipid production for D. salina. Thus, it was necessary to determine the optimum nitrogen concentration for the growth of this alga. Adifferent concentrations of sodium nitrate (0.0, 0.25, 0.5, 1.0 (control), 1.5 and 2.0 g/L ) were investigated on growth and lipid production. The obtained results revealed that the growth of D. salina was markedly increased with increasing the concentration of sodium nitrate up to (2.0g) more than its corresponding control (1.0 g). On the other hand, the biosynthesis and accumulation of lipids were markedly increased nitrate deprived up to (0.5g).
The previous results indicated that nitrogen depreviation is a feasible tool for the over production of lipid contents and the relation between lipids and growth was found to be inversely.
7-Effect of different wave length (λ) of light on growth parameters and lipid% of D. salina:
In this experiment, D. salina was grown at different wave length (λ) (clear white, yellow, green and Red). Results indicated that the clear white light considered the most suitable wavelength for photosynthetic rate in D. salina. It gave the maximum growth and lipid content more than the others wave length. Yellow and green light did not show positive trend in the growth rates compared to clear light (white light) wavelength. So, higher light absorption rate would allow the chloroplast to manufacture increased amounts of usable chemical energy, which would result in an increase in algal growth (biomass).
Amino acid analysis of D. salina grown in both basal and modified media:
Total free amino acids were measured in D. salina grown in both basal and modified media. Free amino acids vary from cells stressed (modified medium) to cells grow in controlled condition (basal medium). Results indicated that there were reduction in free amino from modified mediumto abasal medium. The most reduction in treated cell may be related to the stress condition which pushed the cell to convert the amino acid into lipid accumilation through the deamination and conversion of α- keto acid in to lipid and oil biosynthesis.
Gas liquid chromatography (GLC) analysis of biodiesel extract from D. salina of basal medium and modified one:
Gas liquid chromatography analysis of fatty acid methyl esters of D. salina from both basal medium and modified medium which contain the optimum concentration of different nutrients for the over lipid production. The results indicate that there are different types of fatty acids are present in D. salina from Lauric (C12:0) to Arachidic (C20:0) fatty acids most of these fatty acids are saturated. It was found that treating the alga with modified medium resulted in an obvious increase in the relative percentages of saturated fatty acid (SFA) by 92.2% more than its corresponding control (basal medium) by 65.6%. The increase in SFA on modified medium is due to increase in the content of Myristic acid (C14:0) Palmitic acid (C16:0) and Stearic acid (C18:0) while, there was adecrease in unsaturated fatty acid (USFA). On the other hand, there was adecrease in saturated fatty acid in the basal medium. So, highly saturated fatty acids give an excellent cetane number and oxidative stability to biodiesel. Finally, the results of methyle ester profiles of modified medium considered asuitable conditions for lipid production with highly SFA in D. salina according to ASTM.
Physical and chemical characteristics of lipid and biodiesel B20 of D. salina grown in modified medium and basal one.
The physical and chemical properties of lipid and biodiesel of D.salina were characterized and compared with the corresponding of the American standard (ASTM). These parameters include Specific gravity, Kinematic viscosity, flash point, pour point, cloud point, free fatty acid(FFAs), acid value and saponification value. specific gravity (0.8513 g/cm3and kinematic viscosity at 50 0C (2.4 cSt ) acid value decreased from 33 mg KOH/g (lipid) to 0.78 mg KOH/g (biodiesel). As well as also, the flash point is (129 0C), pour point (-6 0C) and cloud point (0 0C). There were other properties such as total sulfur (0.54), carbon residue (0.002) and Copper corrosion. The Cetane Number is a measure of the ignition quality of diesel fuel The higher the cetane number, the easier it is to start a standard (direct injection) diesel engine is (50.5). All these properties are also cope perfectly with American biodiesel standard (ASTM). Meaning that the biodiesel extracted from modified medium is high quality biodiesel according to ASTM .