Papers by Keyword: Kaoline

Abstract: The aim of this study was to investigate the effect of temperature on adsorption behavior of di-n-butyl phthalate (DBP) in kaoline and montmorillonite. Adsorption isotherms experiments were conducted at 288, 298 and 308 K, respectively. Results showed that adsorption capacity decreased and adsorption intensity enhanced with temperature increased in both minerals. Adsorption amount was larger in montmorillonite than in kaoline. Thermodynamic data indicated the process was a spontaneous and exothermal process and the dominant affection was physical adsorption.

Abstract: The important effect of yoghurt on people's health caused increasing of many technological works and researches not only in our country but also all over the world.The environment in which yoghurt kept, may cause many sort of germs and contamination paths by the effects of some factors which are fairly similar to its own structure. These factors change the shelf-life of yoghurt and finally cause spoilage in yoghurt. In this context, it is known that the scientific works in this area which are aiming to minimize this spoilage effect, focus on the yogurt structure and packaging of yoghurt. The aim of this paper is to improve a smart polymer material which interacts with serum and changes color of the package by considering serum occurring within the shelf-life of yoghurt. PP based material will be used with the biological agencies like “kaoline” and “talc” and implemented mainly or superficial, the color change will be arised if the serum's PH increases. In practice, everyone can see the color changes with the window which will be placed on the label and the window will include the cautions according to the color levels.

Abstract: β-sialons prepared from pyrophyllite resp. kaoline were used for investigation of corrosion resistance in aluminium, NaF-AlF3 and NaCl-KCl mixture. The results were compared with β-sialon of similar composition, prepared from commercial powders. The differences in corrosion process of β-sialon prepared from natural hydrosilicates and synthetic powders are discussed.

Abstract: A kaolin obtained from a region near to San Luis Potosí (México) was characterized by X-ray powder diffraction (DRX), optical microscopy (OM), scanning electron microscopy (SEM), X-ray fluorescence (XRF), thermal analysis (DTA/TGA), and chemical analysis. Mineralogical and morphological characteristics of the mineral are presented. The kaolin sample was formed mainly by kaolinite, but other minor phases were also detected such as quartz, cristobalite, trydimite, and dolomite. For iron lixiviation process, concentrate HCl was employed. The high content of volcanic glass detected, evidenced by optical microscopy, revealed an incomplete kaolinization process of the raw material. In agreement with these results, X-ray fluorescence analysis showed high- SiO2 and low-Al2O3 content in the sample as is expected on weakly kaolinized materials.

Abstract: Mullite whiskers have been manufactured by firing compacts of kaolin, Al2(SO4)3 and (NH4)2SO4 powders, with a small addition of Na2SO4, in air at 1400o C for 15 h. From the batch composition of Al2O3/SiO2 = 0.7, molar ratio, alumina-deficient (Al2O3/SiO2 = 1.02, molar ratio), orthorhombic mullite whiskers with an aspect ratio of >30 (0.2-0.4 μm in diameter) were obtained. With increasing Al2O3/SiO2 molar ratio, the size and aspect ratio of the mullite whiskers decreased.

Abstract: Malaysia mainly produced low quality kaolin and the paper describes the development of a chemical process to produce high purity alumina and zeolite from this mineral. Selective leaching technique was applied to remove 45% of the Al2O3 content in kaolin. The high purity alumina produced shows similar characteristic to the commercial product. An alkaline fusion stage was then carried to transform the kaolin mineral into zeolite. Identification of the crystalline phase by XRD shows that it consists of both zeolite P and hydroxysodalite.

Abstract: In this study, the production of β-Si6-zAlzOzN8-z (z =3) powders by the carbothermal reduction and nitridation of kaolin (Al2O3.2SiO2.2H2O) of Turkish origin (Can-Canakkale) was carried out with different processing parameters. It was found that the morphology of the produced SiAlON powder was mixture of irregular and whisker like grains. Therefore this morphology is suitable for liquid metal infiltration since the powders are already high porous. The kaolin powder containing stoichiometric rate carbon black and 30 % charcoal were pressed and reacted under nitrogen flow (2 lt/min) between 1400-1475°C for 4 h. After a carbothermal reduction and nitridation (CRN) process, porous β- SiAlON ceramic was produced from natural kaolin. Residual carbon and charcoal in the produced ß-SiAlON ceramic were fired at 1000°C giving extra porosity. The porous ß-SiAlON ceramics were sintered under N2 atmosphere at 1550°C for 2 h to make preform for infiltration process. SEM image analyses were carried out to determine preform and pore morphology and XRD analysis were performed for phase transformation.

Abstract: Bioleaching is technology applicable to iron extraction from low-grade non-metallic raw materials. Bioleaching of quartz sands and feldspars involves the action of heterotrophic bacteria. Impurities include fine – grained limonite, goethite, hematite or mica were removed by the reductive dissolution of Fe3+ in linked with the silicate mineral destruction. Heterotrophic bacteria produced organic acids that are able to solubilize Fe oxide and silicates but require organic carbon as a source of energy. Molasses is a relatively inexpensive carbon source used for various industrial fermentations and contains also other nutrients that accounted for the enhancement of iron dissolution in this study. The admixture of pigments in molasses coloured the samples, but the discoloration could be removed by the addition of NaClO following the bioleaching step. The feasibility of the bioleaching treatment has to be tested specifically to each type of silicate raw materials. The Fe content in the quartz sands and feldspar samples by the biological leaching decreased as much as 60% and by subsequent using of electromagnetic separation of feldspars, the decrease of Fe content in 74% was achieved. However, the application of magnetic separation of quartz sands after bioleaching resulted in total iron removal of 93 % and in such combined way prepared product contained 0.024 % of Fe2O3. Achieved results on iron removal point to the fact that combination of leaching and magnetic separation enables to obtain product usable in glass and ceramic industry.

Abstract: In this paper, a central composite design was applied to optimize the bioleaching of iron from a kaolin sample containing 2.2% iron impurity by Aspergillus niger isolated from pistachio shell. The strains were inoculated into 500 ml flasks containing 100 ml media consisted of (g/l): sucrose 120; NH4NO3 0.45; KH2PO4 0.1; MgSO4.7H2O 0.3; FeSO4.7H2O 10-4; ZnSO4.7H2O 25×10- 5. The effects of initial pH, sugar and spore concentrations on iron removal extent were investigated. The two-level factorial design points were pH 2 and 5, sugar conc. 70 g/l and 130 g/l, spore conc. 9×107 and 35×107 spores/l. Also, the increase of dissolved iron, oxalic acid concentration, changes in pH value, and sugar concentration were registered. Consequently, after 10 days, the iron concentration of the best condition reached to 179.3 ppm that means 38.8% of the total iron content is removed. Furthermore, the data analysis showed that all the factors are significant, and the iron removal extent increases by increasing the initial pH to 4.4, sucrose content to 93.8 g/l, and spore concentration to 305.5 spores/μl, but further increase in each factor value has negative effect on the response.

Abstract: In this work, bioleaching of iron from a kaolin sample was carried out using two different strains of Aspergillus niger, and the effects of strain type, pulp density, and addition time of clay on the iron removal were investigated using a full factorial design. It is concluded that strain type has the most significant effect on the iron removal. Also, the highest removal extent was 42.8% that was achieved by using the strain isolated from pistachio shell at the pulp density of 20 g/l, when the clay was added at the beginning of the experiments. The results showed that for the experiments in which the clay was added in the first day of cultivation, the average organic acids concentration (citric acid: 5.6 g/l, and oxalic acid: 4.54 g/l) were higher in comparison to those experiments in which the clay was added in the third day (citric acid: 5.25 g/l, and oxalic acid: 2.87).