Browsing by Author "Aysu, T."

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The Effect of Boron Minerals on Pyrolysis of Common Reed (Phragmites Australis) for Producing Bio-Oils
(Taylor & Francis inc, 2014) Aysu, T.
Pyrolysis of common reed (Phragmites australis) stalks were performed in a fixed-bed tubular reactor with (tincal, colemanite, and ulexite) and without catalyst at three different temperatures (400, 500, and 600 degrees C) with a constant heating rate of 30 degrees C/min and sweeping gas (N-2) flow rate of 100 cm(3)/min. The amounts of solid (bio-char), liquid (bio-oil + water), and gaseous products were calculated and the compositions of the bio-oils were characterized by gas chromatography/ mass spectrometry. The effects of pyrolysis parameters, such as temperature and catalyst, on the product yields were investigated. The results show that both temperature and catalyst have significant effects on the conversion of Phragmites australis into solid, liquid, and gaseous products. The highest liquid yield of 34.67% by weight, including aqeous phase, was obtained with 10% ulexite at 500 degrees C. Further, 101 different compounds were identified by gas chromatography-mass spectrometry in the bio-oils obtained at 500 degrees C.
The Liquefaction of Heracleum Persicum by Supercritical Fluid Extraction
(Taylor & Francis inc, 2013) Aysu, T.; Kucuk, M. M.
Milled Heracleum persicum stalk was converted to liquid products by using organic solvents (methanol, ethanol, acetone, and 2-butanol) with catalysts (10% NaOH or Na2CO3) and without catalyst in an autoclave at temperatures of 518, 538, and 558 K. The liquid products were extracted by liquid-liquid extraction (benzene and diethyl ether). The percentage yields from supercritical methanol, ethanol, 2-butanol, and acetone conversions were 49.1, 55.7, 58.7, and 71.0 at 558 K, respectively. In the catalytic run with NaOH, the highest conversion was obtained by using ethanol as a solvent at the same temperature. The yields of conversion were analyzed by GC-MS.
Removal of Crystal Violet and Methylene Blue From Aqueous Solutions by Activated Carbon Prepared From Ferula Orientalis
(Springer, 2015) Aysu, T.; Kucuk, M. M.
Ferula orientalis L. stalks were used as an agricultural solid biomass waste for preparation of activated carbon with zinc chloride activation using slow pyrolysis in a fixed-bed reactor. The chemical characteristics of the activated carbon obtained at 550 A degrees C were identified by elemental, fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, scanning electron microscopy analyses and found to have a surface area of 1,476 m(2)/g. The ability of the activated carbon to adsorb methylene blue and crystal violet from aqueous solutions has been investigated. Adsorption studies were performed at different initial dye concentrations (200-800 ppm), contact time (0.5-90 min) and temperature (25-45 A degrees C). Adsorption data were modeled with Langmuir, Freundlich and Temkin adsorption isotherms. Equilibrium data of the adsorption processes showed that adsorption of methylene blue is fitted to the Langmuir and crystal violet to the Freundlich isotherm. Pseudo-first-order, pseudo-second-order and Elovich kinetic models were used to analyze the kinetic data obtained at different initial dye concentrations. The adsorption kinetic data were very well described by the pseudo-second-order model. The calculated thermodynamic parameters such as change in free energy, enthalpy and entropy showed that adsorptions of both dyes onto activated carbon were spontaneous and endothermic under the experimental conditions.