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Öğe DETERMINATION OF THERMODYNAMIC PARAMETERS OF POLY (VINYL-CHLORIDE) USING INVERSE GAS-CHROMATOGRAPHY(Scientific Technical Research Council Turkey, 1995) KAYA, I; CEYLAN, K; OZDEMIR, ESome thermodynamic parameters such as partial molar enthalpy, Delta H-1(s), and molar entropy, Delta S-1(s), for sorption; partial molar free energy, Delta G(1)(infinity), weight fraction activity coefficient, (a(1)/w(1))(infinity), and Flory-Huggins interaction parameter, chi, for poly (vinyl chloride)-n hexane, methylacetate, benzene and toluene systems at infinite dilution were found by using the IGC technique. Also, the solubility parameter of poly (vinyl chloride) at an infinite dilution was found by plotting the graph [(delta(1)(2)/RT) - chi/V-1)] versus solubility parameters of some probes, delta(1).Öğe DISSOLUTION OF 2 TURKISH LIGNITES IN TETRALIN UNDER HYDROGEN OR NITROGEN - EFFECTS OF THE EXTRACTION PARAMETERS ON THE CONVERSION(Butterworth-Heinemann Ltd, 1992) CEYLAN, K; OLCAY, ATwo Turkish lignites were extracted with tetralin in a batch autoclave under nitrogen or hydrogen atmosphere. The isothermal extraction temperatures ranged from 325 to 425-degrees-C at 25-degrees-C intervals and the isothermal extraction periods were 0, 30, 60 and 120 min. After removal of char and solvent, the remaining products, which were completely soluble in tetrahydrofuran, were separated into three fractions: preasphaltenes (benzene insolubles), asphaltenes (benzene soluble, n-pentane insolubles) and oils (n-pentane solubles) by successive extractions with benzene and n-pentane. The variations in coal conversion and soluble product composition were investigated with respect to the extraction conditions. The conversion was low below 350-degrees-C but high above 375-degrees-C. As the conversion of the lignites increases, transformation of tetralin to naphthalene also increases. An increase in extraction period affects the product composition but not the percentage conversion, at temperatures of 400-degrees-C and above. In general, the effect of type of gaseous atmosphere on the total conversion was minor. Depending on the extraction conditions, however, the gaseous atmosphere affected the soluble product composition.Öğe DISSOLUTION OF LIGNITES IN TETRALIN UNDER HYDROGEN OR NITROGEN - EFFECTS OF EXTRACTION CONDITIONS ON SULFUR DISTRIBUTION AMONG THE PRODUCTS(Butterworth-Heinemann Ltd, 1994) CEYLAN, K; OLCAY, ARemoval and distribution of sulfur among the extraction products of two Turkish lignites (Beypazari and Tuncbilek) were investigated. Extraction was carried out in tetralin at 325-425-degrees-C under nitrogen or hydrogen. Increasing extraction time and temperature increased the amount of sulfur in both soluble and gaseous products. Most of the sulfur in Beypazari lignite was found in the soluble products, whereas most of that in Tuncbilek lignite passed into the gaseous products. The extraction process did not affect the ash sulfur, but the combustible sulfur content of the char decreased with increasing extraction time and temperature. The results suggest that these two lignites have substantially different sulfur functionalities, and that besides the extraction conditions, the structure of the sulfur in the original lignite has an important effect on the extent of sulfur removal and on the distribution of sulfur among the products. Prolonged extraction at high temperatures results in desulfurization of the soluble products, and interaction between H2S and char is likely under these conditions.Öğe EFFECTS OF TREATMENTS ON THE MINERAL MATTER AND ACIDIC FUNCTIONAL-GROUP CONTENTS OF TURKISH LIGNITES(Butterworth-Heinemann Ltd, 1995) ONAL, Y; CEYLAN, KSix Turkish lignites were treated with solutions of HCl or EtONa at ambient temperature or at 150 degrees C. The proximate analysis, forms of sulfur, acidic functional groups and calcium contents of the raw and treated lignites were determined. The solutions after treatment were analysed for calcium. The effects of the treatment on certain structural components of the lignites varied from one lignitie to another. HCl treatment was effective in ash reduction and in the transformation of carboxylate species to carboxylic acids, but not in desulfurization. The ash reduction was accompanied by an increase in combustible sulfur. EtONa treatment was effective in desulfurization but not in ash reduction or in the removal of chelate- or salt-forming cations. The results suggested that this treatment promoted selective cleavage of certain chemical bonds, such as ester, ether or carbon-sulfur bonds, resulting in an increase in acidic functional groups of the lignites, desulfurization and partial dissolution FT-i.r. spectroscopy and X-ray diffractometry provided some additional evidence regarding the changes in lignite structure due to the treatments.Öğe LOW-TEMPERATURE CARBONIZATION OF TUNCBILEK LIGNITE - EFFECTIVENESS OF CARBONIZATION FOR DESULFURIZATION(Elsevier Science Bv, 1989) CEYLAN, K; OLCAY, A[Abstract Not Available]
