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Öğe ANTIOXIDANT ACTIVITIES OF BLACK CUMIN (NIGELLA SATIVA L.) SEEDS CULTIVATING IN DIFFERENT REGIONS OF TURKEY(Wiley, 2010) Sen, Nejdet; Kar, Yakup; Tekeli, YenerIn this study, the antioxidant activity of the methanolic extracts of the black cumin (Nigella sativa L.) seeds collected from Konya, Isparta, Corum, Burdur, Afyon and Samsun was evaluated using three different methods, specifically the beta-carotene and linoleic acid system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power assays. Among the six black cumin samples of different origins, the black cumin sample origins from Konya city showed the most potent radical scavenging activity in each assay, showing 94.59% (at 1 mg/mL) in the beta-carotene bleaching method and 44.44% in the DPPH radical scavenging method (at 0.5 mg/mL). Positive correlations were found between the total phenolic content in the black cumin extracts and their antioxidant activities. The values of their antioxidant activity were either equivalent to or higher than those of positive BHA and BHT controls. These satisfying results lead to expect the use of black cumin seeds as health-promoting ingredients such as dietary supplements and nutraceuticals.Öğe Catalytic pyrolysis of the oily seeds of Styrax officinalis L. for bio-fuels and valuable industrial chemicals(Wiley, 2012) Kar, Yakup; Sen, NejdetThe catalytic pyrolysis of the oily seeds of Styrax officinalis L., which was carried out using two catalysts in a fixed-bed reactor. As a catalyst, expanded perlite was firstly used according to the best current knowledge. Pyrolysis experiments were performed under at 450 degrees C temperature and 25 degrees C/min heating rate. The results showed that both catalyst materials had approximately the same effect on the bio-oil yields. By using the natural zeolite and expanded perlite at a ratio of 30 wt %, the maximum bio-oil yields were achieved as 38.07 wt % and 37.49 wt %, respectively. The oxygen content is important to bio-oil and upgrading oil. High oxygen content causes poor heating value and instability. The use of a catalyst greatly reduced the oxygen content of the bio-oil, such that the 30 wt % of oxygen content for noncatalytic oil decreased to 16.34 wt % and 18.35 wt % with use of natural zeolite and expanded perlite, respectively. Higher heating values (34.84 and 33.48 MJ/kg) and H/C atomic ratios (1.47 and 1.51) for the catalyzed bio-oils were very close to those of petroleum, which are 40 MJ/kg and 1.5:1.9, respectively. In addition, the oxygenated species decreased and also the quantities of alkyl and alkenyl substituted aromatic compounds and paraffinic alkanes in the catalyzed bio-oils were notably higher than those of noncatalyzed bio-oils when using a catalyst. The use of catalysts in the pyrolysis not only increased the yield of bio-oil, but also produced higher quality oil with higher calorific value, lower oxygen content, higher carbon, and hydrogen contents etc. (C) 2011 American Institute of Chemical Engineers Environ Prog, 2011Öğe Pyrolysis of black cumin seed cake in a fixed-bed reactor(Pergamon-Elsevier Science Ltd, 2011) Sen, Nejdet; Kar, YakupThe black cumin seed cake (BCSC) is a by-product obtained from the black cumin seeds with cold pressing. This by-product can be utilized as a biomass feedstock for conversion to bio-oil with pyrolysis process. The BCSC samples were initially pyrolyzed on a lab-scale pyrolysis system at different values in the ranges of 300-800 degrees C and 0.050-0.300 L min(-1) to determine the effects of operation temperature and N-2 flow rate on the yields on products, respectively. Then, the bio-oil in the highest yield (wB = 44.37%) which was obtained at pyrolysis final temperature (450 degrees C) temperature, heating rate (35 degrees C min(-1)) particle size (dp > 850 mu m), and sweeping flow rate of 0.200 L min(-1) was characterized by Fourier Transform infra-red (FT-IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS) and column chromatography. Consequently, it was shown that the operating temperature and N-2 gas flow rate parameters were effective on the product yields. Also, the important some physico-chemical properties of the pyrolytic oil obtained in high yield were determined as the calorific value of 38.48 MJ kg(-1), the empirical formula of CH1.651O0.105N0.042S0.001, the rich chemical content containing many different chemical groups, and the density of 970.25 kg m(-3), and the viscosity of 63.42 mm(2) s(-1). Based on the determined properties of the pyrolytic oil, it was decided that the use of pyrolytic oil derived from the BCSC may possible be for the production of the alternative liquid fuels and finely chemicals after the necessary improvements. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Usability of terebinth (Pistacia terebinthus L.) fruits as an energy source for diesel-like fuels production(Pergamon-Elsevier Science Ltd, 2012) Kar, Yakup; Sen, Nejdet; Deveci, HuseyinThis study examined the effects of varying pyrolysis parameters, including final temperature, heating rate, particle size, and nitrogen flow rate, on the yields of terebinth as a source of bio-oil. The maximum bio-oil yield of 58.99 wt.% was almost equal to diesel fuel in terms of its major fuel properties (H/C = 1.73, 38.50 MJ/kg, 0.954 g/cm(3), and flash point of 59 degrees C). The GC MS and H-1-NMR analysis results showed that bio-oil predominantly comprised aliphatic hydrocarbons with high heating value and other valuable compounds with potential added value. The results show that the bio-oil can be used as a feedstock for the production of the diesel-like fuels or refined chemicals. (C) 2012 Elsevier Ltd. All rights reserved.
