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Abstract

The purpose of this study was to determine the possibility of producing hydrophobic mesoporous mineral-carbon sorbents from aluminum hydroxide and coal-tar pitch-polymer compositions by carbonization at 600 °C in an nitrogen atmosphere. The method of homogenization was optimized using different solvents. Blends of aluminum hydroxide and coal-tar pitch with a definite composition or the products of co-precipitation of aluminum hydroxide in the coal-tar pitch-polymer medium were subjected to carbonization process. The hydrophilic–hydrophobic properties were evaluated by adsorption of water vapors. The highest value of BET surface area about 370 m2/g, was achieved for the carbonization product obtained from co-precipitated raw components with 10 wt% coal-tar pitch-polymer compositions.

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Investigations were carried out on the kinetics of thermal decomposition of basic aluminium ammonium sulfate in vacuum. The kinetic model of dissociation of the compound was identified. The results of the kinetic studies and the mechanism of the process are discussed.

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The course of thermal decomposition of basic aluminium ammonium sulfate was investigated. Temperature ranges were established in which dehydration of the compound and liberation of ammonia and sulfur oxides take place. The presented scheme of thermal dissociation of the basic salt was based on the determination of the solid and gaseous products of the reaction.

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Journal of Thermal Analysis and Calorimetry
Authors: Barbara Pacewska and Dariusz Szychowski
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Abstract  

The purpose of this study was a preliminary evaluation of mineral-carbon sorbents preparation possibility by the method of thermal decomposition of a mixture of aluminium oxide or hydroxide and acenaphthene and determination of their physicochemical properties. The conditions of carbonization were established and the changes of physicochemical properties of obtained materials as a function of organic substance content in the mineral-carbon mixture before the process of carbonization were tracked. In these investigations the methods of thermal analysis, low-temperature nitrogen adsorption and benzene vapors adsorption were applied.

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Summary An attempt was made to obtain mineral-carbon sorbents from waste products of petrochemical industry: lime from the decarbonization of river water to be used in technology and hydrocarbon wastes obtained in the treatment of industrial waste waters. The sorbents were prepared by thermal decomposition of mixtures of the mineral and carbon components. In order to optimize the preparation conditions, physicochemical studies were performed of both the mineral matrix and the mineral-carbon sorbents. Adsorption measurements involving nitrogen, water, and benzene as adsorbates were used for determining the parameters of porous structure of the obtained materials and their hydrophilic-hydrophobic properties. The properties influencing the sorptive properties of the organic compounds present in the petrochemical wastes were pointed out.

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Abstract  

The paper concerns aluminium hydroxides precipitated during hydrolysis of aluminium acetate in ammonia medium, as well as aluminium oxides obtained through their calcination at 550, 900 or 1200�C for 2 h. The following techniques were used for analysing of obtained materials: thermal analysis, IR spectroscopy, X-ray diffraction, low-temperature nitrogen adsorption, adsorption-desorption of benzene vapours and scanning electron microscopy. Freshly precipitated boehmite/pseudoboehmite had high value of S BET, very good sorption capacity for benzene vapours, developed mesoporous structure and hydrophilic character. After prolonged refluxing at elevated temperature its crystallinity increased which was accompanied by a decrease of specific surface determined from nitrogen adsorption, decrease of sorption capacity for benzene vapours and weakening of the hydrophilic character. Calcination of all hydroxides at the temperature up to 1200�C resulted in the formation of α-Al2O3 via transition forms of γ-, δ-and θ-Al2O3. The samples of aluminium oxides obtained after calcination at 550 and 900�C were characterised with high values of specific surface area and displayed quite high heat resistance, probably due to a specific morphology of starting hydroxides. The process of ageing at elevated temperature developed thermal stability of aluminium oxides.

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Journal of Thermal Analysis and Calorimetry
Authors: Barbara Pacewska, D. Szychowski, and A. Wendt
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