Browsing by Author "Esim, Nevzat"

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Bio-Oil Production Via Catalytic Pyrolysis of Anchusa Azurea: Effects of Operating Conditions on Product Yields and Chromatographic Characterization
(Elsevier Sci Ltd, 2016) Aysu, Tevfik; Durak, Halil; Guner, Serkan; Bengu, Aydin Sukru; Esim, Nevzat
Pyrolysis of Anchusa azurea, a lignocellulosic gramineous plant, was carried out in a tubular, fixed-bed reactor in the presence of four catalysts (Ca(OH)(2), Na2CO3, ZnCl2, Al2O3). The influences of pyrolysis parameters such as catalyst and temperature on the yields of products were studied. It was found that higher temperature resulted in lower liquid (bio-oil) and solid (bio-char) yields and higher gas yields. Catalysts effected the yields of products differently and the composition of bio-oils. Liquid yields were increased in the presence of Na2CO3, ZnCl2 and Al2O3 and decreased with Ca(OH)(2). The highest bio-oil yield (34.05%) by weight including aqueous phase was produced with Na2CO3 catalyst at 450 degrees C. The yields of products (bio-char, bio-oil and gas) and the compositions of the resulting bio-oils were determined by GC-MS, FT-IR and elemental analysis. GC-MS identified 124 and 164 different compounds in the bio-oils obtained at 350 and 550 degrees C respectively. (C) 2016 Elsevier Ltd. All rights reserved.
Health Attributes of an Endemic Orchid From Eastern Anatolia, Dactylorhiza Chuhensis Renz&taub. - in Vitro Investigations
(Elsevier Gmbh, 2015) Dalar, Abdullah; Guo, Yu; Esim, Nevzat; Bengu, Aydin Sukru; Konczak, Izabela
Phytochemical composition and potential health attributes of Dactylorhiza chuhensis Renz&Taub., an endemic orchid from Eastern Anatolia, were investigated. Lyophilized methanol-based extracts obtained from leaf, flower, stem and tuber were investigated for the presence of phenolic compounds [Folin-Ciocalteu assay and high performance liquid chromatography analysis (HPLC)], antioxidant capacities [ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assay] and enzyme-inhibitory activities [lipase, alpha-amylase, alpha-glucosidase and angiotensin converting enzyme (ACE)]. The tuber, used as a traditional remedy and utilized by the pharmaceutical industry, had the lowest content of total phenolics, inferior antioxidant and enzyme-inhibitory activities. The highest phenolic content (44.9 +/- 0.8 mg GAE/g DW) was exhibited by the leaf extract, which also showed superior reducing (736.8 +/- 16.2 mu mol Fe2+/g DW) and oxygen radical scavenging capacities (2715.8 +/- 83.5 mu mol Trolox E/g DW). The inhibitory activities of the leaf extract toward alpha-amylase, alpha-glucosidase and ACE were moderate. Applied at non-toxic concentrations, the leaf extract effectively reduced accumulation of nitric oxide (NO) in lipopolysaccharide (LPS)-activated hepatocellular carcinoma (HepG2) cells. Further studies towards potential utilization of D. chuhensis leaf as a source of physiologically active phytochemcials are justified. Crown Copyright (C) 2015 Published by Elsevier GmbH. All rights reserved.
Supercritical Liquefaction of Common Reed (Phragmites Australis) With Alkali Catalysts
(Taylor & Francis inc, 2016) Aysu, Tevfik; Esim, Nevzat
Milled Phragmites australis was liquefied in organic solvents with and without catalyst in a cylindrical reactor at temperatures of 533, 553, and 573 K under supercritical conditions. The liquefied compounds were extracted with diethyl ether and benzene using an extraction procedure. The product yields without catalyst in supercritical methanol, ethanol, and acetone were found to be 55.4%, 64.4%, and 73.5% at 573 K respectively. The highest conversion to liquid products was obtained in supercritical acetone with 10% sodium hydroxide as catalyst at the same temperature in the catalytic runs. Main chemical compounds present in the liquid products obtained in ethanol without catalyst and acetone with sodium hydroxide catalyst at 573 K were analyzed and characterized by gas chromatography-mass spectrometry (GC-MS).