Papers by Author: Thanakorn Wasanapiarnpong

Abstract: Bituminous coal ash, fly ash (FA) and bottom ash (BA), from coal power plant were studied in this research for utilizations in ceramic and pottery industries. Both fly ash and bottom ash mixed with four different ball clays from two kinds of ceramic pottery products such as flowerpot and construction brick, Ratchaburi, Chantaburi, Angthong and Chonburi ball clay. The mixtures were varying ratio between ashes and clays depend on clay sources. After mixing, the bodies were formed to test pieces and were then fired at 800-1200 °C. The results indicated that, added fly ash 0-40 wt% significantly decreased water absorption and increased bending strength when fired at 1150 °C or above. For color effect, CIE L*a*b* color space, both fly ash and bottom ash revealed the samples less lightness, more red and yellow appearance. These results are obvious when fired at 1150 ^oC or above. Following the results, fly ash is possible to be used in ceramic pottery industries replaced with other addition such as sand and pottery stone.

Abstract: Si₃N₄ ceramics were sintered at relatively low temperature of 1400-1650 °C with additives from the SnO₂-SiO₂-MgO-Bi₂O₃-Y₂O₃ system. The degree of densification, α-β transformation, mass loss and microstructure were measured as a function of additives composition, sintering temperature, and nitrogen gas pressure. Specimen prepared from 3 mass% SnO₂, 3 mass% SiO₂, 3 mass% MgO, 6 mass% Bi₂O₃, and 5 mass% Y₂O₃ as the sintering additive could be sintered to almost full density at relatively low temperature as 1550 °C for 2 h under ambient pressure of nitrogen atmosphere. The α-β transformation was not completed at this condition. The mass loss was relatively high due to the evaporation of SiO₂, MgO and Bi₂O₃. However, the resulted dense materials have high bending strength.

Abstract: The pottery of Ratchaburi is very famous especially dragon jar which was fired by using dragon kiln. The kiln was made of unfired clay bricks, which its properties including high refractoriness, low thermal shrinkage and durable are desired. Aluminum hydroxide is an interesting material for improving brick’s properties, providing high active alumina (gamma-alumina) content after decomposition, high melting point and also reasonable cost. The study evaluated the effect of an additive, Al (OH)₃, on the fried properties of refractory clay brick. In this study, four difference proportions of Al (OH)₃ to clay , including 0:100, 25:75, 49:51 and 76:24 were studied. The specimens of 5x5x5 cm³ were formed by hand molding, then were fired at 1200, 1300 and 1400°C. The properties including refractoriness, volume shrinkage, strength, bulk density, water absorption, and slaking time were investigated. The samples of 25:75 ratio of Al (OH)₃ to clay, which was fired at 1300°C exhibited high in refractoriness, low volume shrinkage of 5% and relatively low density of 1.69 g/cm³ as compared to those of 1400°C fired. Moreover, the moderate water adsorption of 15 % and useable compressive strength of 12.4 MPa was also observed. As a result, these properties suitable for using in firebox of dragon kiln of Ratchaburi province.

Abstract: Ceramic cookware can be taken a direct flame or stove top for the duration without damage. The selected materials must have low thermal expansion coefficient, high strength, low water absorption and high thermal shock resistance, reasonable in cost and easy to be produced. Cordierite and spodumene composite has been interested for ceramic cookware due to their fitted properties. In previous work, study in the cordierite-spodumene composite with low thermal expansion coefficient of 2.60 x 10^-6 /°C when sintered at 1250 ^oC with a ratio of spodumene 60 wt% and cordierite 40 wt% can withstand the pot shape samples. However, the sample showed relatively high water absorption and low strength which was not appropriate for using in this application. In this research, mullite is added in the formula to improve strength and densification of ceramic composites. Spodumene, ball clay, calcined talc and calcined alumina are used as starting raw materials and formed by slip casting. All samples are sintered in a temperature range from 1250-1275 °C in an electric furnace. Water absorption and bulk density were tested by Archimedes method, modulus of rupture was tested by the three-point bending method, microstructure were investigated by SEM and the coefficient of thermal expansion was measured by dilatometer. It was found that the mullite phase was investigated when adding mullite more than 30 wt% in cordierite-spodumene composite.

Abstract: Titanium dioxide (TiO₂) is the one of photocatalyst materials that widely used for decolorization of organic compounds in wastewater by photocatalytic mechanism which can be activated by UV light. Unfortunately, in the case of fine TiO₂ power, filtration of the powder after water treatment process is difficult. In this research, coating or immobilizing the TiO₂ powder on substrates using for removing the color of lignin concentration is interesting. The objectives of this research are to prepare the floating porous cylindrical tube substrates composed of zeolite NaA and ball clay, and then to determine the efficiency of lignin degradation. Zeolite NaA powder, Suratthani ball clay and organic binder solution were mixed before extruding and cutting to be 1.5 cm diameter cylindrical tube with 2.5 cm in length and 0.3 cm in thickness. After that, the dried tubes were fired at 650 - 800 °C for 2 hours and were then coated with TiO₂-P25 suspension before re-firing at 600 °C for 1 hour in an electrical furnace. The fired uncoated tubes were characterized in terms of phase composition, porosity and radial crush strength. From the XRD pattern of the tubes fired at 800 °C showed that the zeolite NaA phase was disappeared. On the other hand, the zeolite NaA phase was found in the samples fired at another lower temperature. For the coated tubes, polyurethane foam was filled into the hole to make the tubes can be floated on the water surface. After that, the photocatalyst degradation property by determining the decreasing of concentration of lignin solution under tungsten lamp irradiation of the floated tubes were tested.

Abstract: Electricity generation at Mae Moh Power Plant in Lampang, Thailand, uses lignite as fuel. The output is 3.0 to 3.5 million tons of fly ash per year and 1.5 to 2.0 million tons of bottom ash per year. Fly ash is widely used in concrete application but for bottom ash, it is not very useful. When considering the phase of bottom ash containing quartz, anorthite and hematite, it was found that there are suitable chemical compositions for replacement of raw materials in ceramic tile. Generally, the stoneware tiles are composed of quartz, mullite, feldspar, and glass phase. Water absorption of stoneware ceramic tiles is below 5%, high strength, fire resistance, and low warpage. Firing or sintering at rather high temperature as 1000-1250 °C is the manufacturing process for this type of tile. The changes in crystal structure and glassy phase formation in tile texture during sintering will be often result the tile to warpage or bent. The more or less lean depends on the viscosity of the glassy phase that occurs at high temperatures in the tile if less viscosity will cause higher warping rate that effect on the shape, and quality of the workpiece. The research has reported that anorthite phase improves the viscosity of a liquid phase or glassy phase when the tile is sintering at high temperatures and lead to high density and low water absorption. This research is interested in studying the effect of using lignite bottom ash as an ingredient in ceramic tile texture to produce low water absorption type by analyzing the effect of percentage of lignite bottom ash to warpage and important properties of ceramic tiles.

Abstract: Phenol and phenolic compounds in wastewater from various industries were toxic to water livings and human even in ppm concentration. A number of photocatalysts and adsorbents were applied for the low cost and good efficiency wastewater management to reduce phenol concentration in water. In this work titanium dioxide, one of high efficiency photocatalysts which is widely used in water treatement, was coated on the fabricated adsorbent composite substrate. The composite substrate composed of activated carbon and NaA zeolite presents high phenol adsorption because of high porosity and good ion exchange properties resulting in good adsorption property. Accordingly, the absorption could promote the photocatalytic activity of TiO₂ catalyst. As the specimens were easily disposed after water treatment process, therefore, it was a good choice for lower energy consumption. The composite substrate was easily fabricated by simple extrusion and fired under non oxidation atmosphere at 650°C for 3 hours. Then polyurethane foam was inserted into the composite substrate to make it be able to float and be swirled by wind near water surface to get more UV excitation than deeper water. Phenol concentration was investigated by the UV absorbance at 270 nm using UV-Vis spectrophotometer. The XRD and SEM were used to study phase crystal structure and morphology of the composite.

Abstract: The objective of this research is to study the feasibility of using fiber obtained from tobacco stalk as reinforcement fiber in the production of fiber cement through hydrothermal methods. The fiber cement samples are made of the mixtures of 50% of ASTM Type I ordinary Portland cement, 35% of milled sand, 10% of calcium carbonate powder and 5% of cellulose fiber (eucalyptus pulp and tobacco stalk pulp). This study include the morphological characterization of the fibers and the study of effects that the use of fiber has on the fiber cement suspensions and on the mechanical and physical properties of the final product. The flexural strength of fiber cement samples using tobacco stalk pulp after curing in an autoclave at 180 °C for 4 hours is 14.21 MPa which is slightly lower than that of the samples using eucalyptus pulp at 17.10 MPa. However, the results obtained in the tests confirmed the high potential of the tobacco stalk as a source of fiber for the fabrication of a fiber cement capable of meeting the requirements of demanding applications.

Abstract: Hybrid composite for drinking water filter aids were prepared by slip casting method. The slip was prepared from the mixture of 17.41% of zeolite Na-A, 17.41% of activated carbon, 0.35% of ZnO nanoparticles, 8.7% of phenolic resin, 0.54% carboxymethyl cellulose and 55.59% of reversed osmosis water. The slip was mixed in a high speed ball mill for 15, 30, 45 and 60 minutes and was then poured into plaster molds for 3 hours in order to maintain hollow casting. The green body was dried and fired at several of firing temperature of 600, 650, 700 and 750 °C. The major characteristics of the composite filter were characterized as: mechanical strength, morphology, pore diameter and ion exchange ability by three points bending, scanning electron microscopy (SEM), mercury porosimetry and inductive coupled plasma-optical emission spectroscopy (ICP-OES), respectively.

Abstract: Activated carbon, zeolite and titanium dioxide are wildly used for removing the organic compounds in waste water. Although, these materials exhibit high performance (in powder form), reclaiming of these materials from the waste water treatment system is still hard. The objective of this study is to fabricate hollow cylinder activated carbon-zeolite samples which were used as a porous substrate. Various ratios of activated carbon, zeolite NaA and clay were mixed with special binder to form dough before extruded to be hollow cylinder shape. The hollow cylinder samples were cut into 2.5 cm long and then were fired at 600 °C for 2 hours under 5%CO₂+N₂ atmosphere. The fired samples were dip-coated with TiO₂-P25 and fired at 600 °C for 1 hour under 5%CO₂+N₂ atmosphere for testing the photocatalytic degradation of lignin solutions under UV light. The results showed that the strength of fired samples increasing with the ratio of clay increased. The XRD patterns of samples having clay addition showed peaks of zeolite and quartz. The physical properties, microstructure and photodegradation will be discussed.