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Öğe Boron removal by ion exchange membranes(ELSEVIER SCIENCE BV, 2005) Ayyildiz, HF; Kara, HBoron removal from aqueous solution was studied through Neosepta-AHA membrane by Donnan dialysis (DD) method as a function of concentration, pH, conduct time, membrane structure and effect of accompanying ions. The feasibility of the system was examined and the highest boron removal was obtained when the pH of the feed phase was 9.5. On the other hand, it was determined that reverse flow transition was accelerated by counter ions and HCO3- ion was found to be more effective than Cl- and SO4-2 ions. It was determined that obtained results of AHA membrane was compared with Neosepta AFN and AMH membranes and the flow rate of boron through Neosepta AHA, AFN and AMH anion exchange membranes were found to be between 3.10(-8)-3232.10(-8) mmol cm(-2) s(-1) depending on concentration of feed and receiver phases, pH as well as counter ion properties. The order for recovery of boron for membranes was found to be as AFN > AMH > AHA. It could be concluded that the DD method is an appropriate method for boron removal from aqueous solution when an appropriate counter anion was chosen at suitable pH value.Öğe Fluoride removal by Donnan dialysis with anion exchange membranes(ELSEVIER SCIENCE BV, 2005) Durmaz, F; Kara, H; Cengeloglu, Y; Ersoz, MThe removal of fluoride from diluted solution with Neosepta AHA anion exchange membrane has been studied by Donnan dialysis. The effects of concentration, pH, and accompanying anion on feed phase and receiving phase composition were investigated. Neosepta AHA anion exchange membrane was used for the removal of fluoride and the flux of fluoride with respect to the concentration, pH, and the effect of the counter-ions (HCO3-, Cl-, SO4-2) were obtained between 34-136.10(-7) (m.mol.cm(-2).s(-1)). The effect of the fluoride flux increased with increasing of concentration on the feed phase. The flux of fluoride was found to be higher at higher pH in the feed phase. In addition, the accompanying counter-anions also influenced the flux of fluoride and the order of flux was founded as HCO3-> Cl-> SO4-2. The results obtained for AHA membrane were compared with Neosepta AFN and polysulfone SB-6407 membranes. The transport efficiencies of the membranes were found to be in the order AFN > AHA > SB-6407.Öğe Investigation of the properties of oil at the bleaching unit of an oil refinery(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2004) Kaynak, G; Ersoz, M; Kara, HColor removal from neutralized Sunflower oil was studied with different kinds of commercial bleaching earths. The effect of changes in time (25 and 35 min), temperature (80-125 degreesC), and bleaching earth dosage (0.1-0.9% by weight) on color, chlorophyll and carotene concentrations, and oxidation degree were investigated. To obtain adsorption Curves from coloring compounds adsorbed onto activated bleaching earths, the Langmuir and Freundlich equations was used, the constant parameters and correlation coefficient R were calculated for each type of bleaching earth, and color changes were explained by both adsorption isotherms. It was observed that an increase in bleaching earth dosage decreases color. Its effect oil oxidation state, however, is complex and related to both primary and secondary oxidation products. In addition, ail increase in temperature seems to decrease chlorophyll and carotene adsorptions. Generally, time beyond equilibrium is considered useless for the removal of unwanted components. This Study also confirms this claim and reveals that the pet-oxide value does not indicate the oxidation state of the oil completely. (C) 2004 Elsevier Inc. All rights reserved.Öğe New options for conversion of vegetable oils to alternative fuels(TAYLOR & FRANCIS INC, 2006) Demirbas, A; Kara, HBiodiesel from transesterification of vegetable oils is an excellent alternative fuel. There is, however, a need to develop a direct process for conversion of vegetable oils into gasoline-competitive biodiesel and other petroleum products. Methyl esters of vegetable oils have several outstanding advantages among other new-renewable and clean engine fuel alternatives. The purpose of the transesterification process is to lower the viscosity of vegetable oil. Compared to No. 2 diesel fuel, all of the vegetable oils are much more viscous, whereas methyl esters of vegetable oils are slightly more viscous. The methyl esters are more volatile than those of the vegetable oils. Conversion of vegetable oils to useful fuels involves the pyrolysis and catalytic cracking of the oils into lower molecular products. Pyrolysis produces more biogasoline than biodiesel fuel. Soap pyrolysis products of vegetable oils can be used as alternative diesel engine fuel. The soaps obtained from the vegetable oils can be pyrolyzed into hydrocarbon-rich products. Zinc chloride catalyst contributed greatly to high amounts of hydrocarbons in the liquid product. The yield of ZnCl2 catalytic conversion of the soybean oil reached the maximum 79.9% at 660 K.Öğe Nightmares and serum cholesterol level: A preliminary report(CANADIAN PSYCHIATRIC ASSOC, 2005) Ağargün, Mehmet Yücel; Gulec, M; Çilli, Ali Savaş; Kara, H; Sekeroglu, R; Dulger, H; Besiroglu, LObjective: To examine whether there is a relation between nightmares and serum lipid levels. Methods: Fifteen subjects who met DSM-IV criteria for the diagnosis of nightmare disorder and 15 healthy control subjects participated in the study. We used an enzymatic colorimetric method for cholesterol and triglyceride determination. We measured high-density lipoprotien (HDL) cholesterol using the direct HDL-cliolesterot method. Low-density lipoprotein (LDL) was calculated according to the Friedewald formula. Results: Patients with nightmare disorder had. lower serum triglyceride, lower total cholesterol, and lower LDL levels than healthy control Subjects. Conclusion: These findings suggest that nightmares are associated with low serum lipid levels.Öğe Synthesis of p-tert-butylcalix[4]arene dinitrile bonded aminopropyl silica and investigating its usability as a stationary phase in HPLC(TAYLOR & FRANCIS INC, 2006) Gezici, O; Tabakci, M; Kara, H; Yilmaz, MThe chromatic separation of adenine, adenosine, cytosine, phenol, benzene, and toluene were investigated by using 5,11,17,23-tert-butyl-25,27-bis(cyanomethoxy)-26-(chloroformyl)-28-hydroxy-calix[4]arene bonded aminopropyl silica (CDBAPS) as a stationary phase. The separation ability of the stationary phase was observed to be good for target species. The effect of non-polar calix[n]arene network was observed in chromatographic processes, and it was thought that, thanks to the relatively polar nitrile groups, further selectivity would be obtained in various chromatographic separations.
