Non-isothermal dissolution kinetics of chromite in alkaline aqueous solution(1998) Volume(issue) 1(2): 57-60.

A. Demirbaş and Y. Abalı

2Department of Chemistry, Celal Bayar University, Manisa, Turkey

The dissolution kinetics of chromite in aqueous KOH solution was studied in the present work. In the experiments, stirring time, stirring speed, particle size, solid-to-liquid ratio, and temperature were chosen as dissolution parameters. It was observed that decrease of the particle size, the solid-to-liquid ratio and increase of the dissolution temperature increased the leaching rate, and the stirring speed has no significant effect on the reaction rate. The dissolution kinetic parameters were the activation energy 61598 J mol^-1 , the pre-exponential factors; 4.38 x 10¹³ min^-1 , and rate constant values 1.55x10³ min^-1.

Optimization of dissolution of calcinated bone in HCl solutions (1998) Volume(issue) 1(2): 61-66.

Y. abalı and E. Mert

Celal Bayar University Faculty of Arts and Science Department of Chemistry 45030 Manisa , Türkiye

In this study, the optimum conditions of dissolution of calcinated bone in HCl solutions with different concentrations are investigated. Using the Taguchi Fractional Design Method, it was found that the optimum process conditions, at which 67.2 % P₂O₅ dissolution was reached, were as follows: Reaction temperature : 318 K, solid-to-liquid ratio: 1/5 (g/ml), acid concentrations :32 (% w/v), stirring speed :400 min^-1 and reaction time: 60 min.

Dissolution kinetics of calcinated magnesite in acetic acid solutions(1998) Volume(issue) 1(2): 67-74

Y. Abalı

Department of Chemistry, Celal Bayar University, Manisa, Turkey

R. Atay¹ and M. Cengiz²

1Eğirdir Fisheries Faculty, Süleyman Demirel University, Eğirdir, Isparta, Turkrey

2Department of Chemistry, Süleyman Demirel University, Isparta, Turkey

K. Arısoy

Department of Chemistry, Celal Bayar University, Manisa, Turkey

A. Okudan, H. Kara, Y. Çengeloğlu and F. Nizamlıoğlu

University of Selçuk, Faculty of Arts and Sciences, 42079 Campus, Konya-Türkiye

 The phenolic compounds, in humic acid extracted from Ilgın Lignite by alkaline extraction was determined by gas chromatography-mass spectrometry. Two temperature gradient programming have been applied. The 14 and 9 (totally 21 because 2 phenolic compounds are in both fractions ) phenolic compounds in two fraction extracted at two different pH (7.5 and 8.3) from humic acid, respectively, were isolated. Most of them have not been, previously, found out in coal derivatives. The separation and identification of phenolic compounds were verified by analysis of the GC-MS and comparisons of the retention time and mass spectra with standards phenolic compounds under computer control were made automatically. Thus the confidence level of this analysis is high The used methods in this work provide a comprehensive separation and identification scheme for phenols in complex samples. such as humic acid.

H. Kara and R. Mirzaoğlu

Selçuk University, Department of Chemistry, Konya, Turkey.

From three different specimens of Central Anatolian lignites, humic acid (HA) were extracted with 2.5% NaOH. Acid washing were used to remove residual caustic from the treated coal. The HA yields extracted from Beyşehir, Ilgın and Ermenek lignites were 32.3%, 25.8% and 21.3% of the coal on dry basis respectively. HA could not be extracted from Dadağı lignite. This might be due to the higher quality rank of this coal. Based on the rank of coals the weight of extracted HA decreased. The general characterization of HA obtained from Beyşehir, Ilgın and Ermenek lignites and some fractions extracted from HA with different solvents were examined. The oils (hexane soluble), asphaltenes (benzene soluble), preasphaltenes (tetrahydrofuran (THF) soluble) and pyridine soluble parts of HA were separated. The HA from Beyşehir lignites is composed of 1,2% oil, 8,5% asphaltenes, 18.4% preaspaltene, 40.1% higher molecular weight (pyridine soluble) and 31.8% non soluble parts. The yields of pyridine extracts obtained from untreated HA were about 71.8%, 64,9% and 60,8% of HA from Beyşehir, Ilgın and Ermenek lignites. The pyridine soluble fractions extracted from untreated HA by a soxhlet extractor were subjected to column chromatography utilizing activated silica gel as the adsorbent and hexane, benzene, methanol and THF as eluents. The eluates of each solutions were separately examined for their compositions.

A. Aslan¹, F. Ö. Karataş² and A. Demirbaş²

1Department of Chemistry, Celal Bayar University, Manisa, Turkey; ²Fatih Education Faculty, Karadeniz Technical University, 61335 Akçaabat, Trabzon, Turkey.

In this study, physical and chemical properties of lignite fly ashes obtained electrofilter from (FAE) and cyclone (FAC), lignite bottom ash (BA), cement+lignite ash mixtures and their effects on stregth, setting, volume expansion, and hydration properties of concrete were investigated. The ashes were classified into two general types based on total silica, alumina, and iron-III oxide: Class C and Class F. The results obtained were compared with the Turkish Standards, in general, were found to be within the limits. As a result, the lignite fly and bottom ash additives can be used as In this study cementitious materials.

Acetic acid, methanol and acetone from lignocellulosics by pyrolysis (1998) Volume(issue) 1(2): 111-115.

A. Demirbaş and D. Güllü

Educational Faculty, Black Sea Technical University, 61335 Akçaabat, Trabzon, Turkey

Thermal depolymerization and decomposition of biomass, cellulose, hemicelluloses, and lignin were formed various products as well as a solid residue of charcoal. A promising route for processing biomass is the pyrolysis which has been conducted under a variety of experimental conditions resulting in production charcoal, tarry material, aqueous fraction, and gaseous products. Acetic acid mainly comes from the acetyl groups of the hemicelluloses. The pyroligneous acid consists of about 50 % methanol, 18 % acetone. Levoglucosan is also sensitive to heat and decomposes to acetic acid, acetone, phenols, and water. Methanol arises from methoxyl groups of uronic acid.