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Nitrogen Source, an Important Determinant of Fatty Acid Accumulation and Profile in Scenedesmus obliquus

100%
Yilancioğlu K., Tekın H., Cetıner S.
Acta Physica Polonica A
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2016
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vol. 130
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issue 1
428-433
EN
The potential of algae-based fuel technologies for manufacturing renewable biofuels has been attracting interest from the scientific community. Biomass productivity and cellular lipid content are important parameters affecting the feasibility of using algae oil for biodiesel production. This study compares utilization of NaNO₃, NH₄Cl and urea as different nitrogen sources in terms of their effects on biomass productivity, fatty acid profile and accumulation in Scenedesmus obliquus. Cellular lipid accumulation was analyzed by gravimetric, fluorometric, and flow-cytometric methods, besides collecting spectrophotometric data for biomass productivity analysis. In addition, fatty acid profiles were compared by using gas chromatography-mass spectrometry. The alga can utilize all tested nitrogen sources successfully however growth rates demonstrate differences. Gravimetric lipid content analysis showed approximately a ≈1.5-fold increase in total lipid accumulation under NH₄Cl regime when compared to that of NaNO₃ and a ≈ 2-fold increase when compared to that of urea at the end of ten days cultivation course. Fatty acid profiles under different nitrogen regimes present variations especially under NH₄Cl regime. Moreover, all lipid extracts mostly consist of saturated, straight- and branched-chain hydrocarbons of different chain lengths ranging from C16-C20 which grant a suitable profile for biodiesel production. Scenedesmus obliquus is a suitable species for biodiesel production. The results obtained from this study provide a better understanding of cultivation characteristics of this important species and support potential, future biodiesel production.
2
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Magnetic Mesoporous Silica Nanocomposite for Biodiesel Production

100%
Erdem S., Öksüzoğlu R., Avşar S., Erdem B.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
763-766
EN
Ordered mesoporous silicas can be utilized as support because of having large surface area, tunable porosity, uniform pore size distribution, high thermal stability and modifiable properties. However, these materials introduce separation problems in liquid-phase processes. We have prepared Fe₃O₄-SBA-15-SO₃H solid acid catalyst by combining the properties of a magnetic material and the mesoporous character of silica. The sulfonic acid functionalized solid acid catalyst, containing both magnetic nanoparticles and mesoporous silica, is not only separable but also stable under hydrothermal conditions, which are usually employed for biodiesel production. Esterification of oleic acid with methanol for biodiesel production was carried out effectively and 75% conversion of ester was approximately reached within six hours in the presence of Fe₃O₄-SBA-15-SO₃H magnetic solid acid catalyst. In addition, the catalyst could be separated from the reaction system by applying external magnetic field and reused without deactivation.
3
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Biodiesel from Oleic Acid by Green Catalyst "Catalytic Membrane": a Solution to Global Warming Problems

80%
Unlu D., Nigiz F., Hilmioglu N.
Acta Physica Polonica A
|
2017
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vol. 132
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issue 3
689-692
EN
In recent years biodiesel is receiving more attention as a sustainable alternative to fossil fuel. Biodiesel has lower exhaust emissions and toxicity compared to petroleum diesel fuel. In this study, biodiesel is produced from the oleic acid esterification process. We try to develop an efficient heterogeneous catalyst for biodiesel synthesis. A catalytic membrane carboxymethyl cellulose with sulfosuccinic acid has been prepared for using as catalyst. Carboxymethyl cellulose is a natural and biodegradable polymer and it has the advantage of green catalysis. Sulfosuccinic acid is a homogeneous catalyst. To overcome the disadvantages of the homogenous catalyst, sulfosuccinic acid is used together with polymeric membranes. The effects of the ethanol/oleic acid molar ratio, the reaction temperature, the sulfosuccinic acid concentration and the stirring speed were investigated to find out the optimum reaction conditions. The catalytic stability of the catalytic membrane is also studied. The optimum conditions for the reaction were found to be 65°C, catalytic membrane with 6 mmol of sulfosuccinic acid, 9:1 ethanol to oleic acid molar ratio and 600 rpm stirring speed. The oleic acid conversion using the catalytic membrane was 85% under these conditions after 6 h. Our findings show that carboxymethyl cellulose membrane with sulfosuccinic acid groups is a suitable catalyst for esterification.
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