Siriporn Larpkiattaworn

Fabrication of ceramic membranes on porous ceramic supports by electrophoretic deposition

Abstract Nanoporous alumina membrane and continuous zeolite L membrane were fabricated on the inner surface of microporous alumina tubes. In the former case, an electrophoretic deposition (EPD) technique was used for the deposition of bimodal alumina particles for the subsequent low temperature sintering. In the latter case, the EPD was used for the seeding process of zeolite L particles for the subsequent hydrothermal synthesis. A thin layer of polypyrrole was synthesised on the inside wall of the porous tubes by the chemical polymerisation of pyrrole to give the wall electric conduction for the EPD electrode. The thickness of the coating layers was controlled by altering the applied voltage and deposition time. The interfacial connection of the alumina or zeolite coated layer and the substrate was evaluated by SEM observations before and after the thermal treatment. The nanoporous structure of the alumina membrane was also characterised by a pore size analyser.

Microstructure and Properties of TCP/HA Composite Materials

Tricalcium phosphate (TCP) and hydroxyapatite (HA) are materials widely used to repair and reconstruct damaged parts of bone. They have been interesting for applying in human skeleton because of their excellent properties of biocompatibility, bioactivity and osteoconduction. Combining TCP and HA as composite material could improve their biological properties for artificial bone. In this work, phase, microstructure, and pore size of TCP/HA composite were observed at the various weight ratio of TCP:HA (7:3, 1:1, 1:4). The mixtures were formed in granule and then sintered at 1200, 1250, and 1300°C. The sintered granules of TCP/HA composite presented the porosity and pore size of 27-45% and 10-17 micron, respectively. The maximum porous sample was observed from TCP/HA composite at the weight ratio of 7:3 and it was selected to test for biocompatible prediction in vitro cytotoxicity by MTT assay.

Hydrothermal Synthesis of Zinc Oxide Nanoparticle from Zinc-Dust Waste for Photocatalytic and Antibacterial Applications

ZnO nanoparticles were successfully synthesized by using zinc dust waste derived from hot-dip galvanizing process as a starting materials via simple hydrothermal method. The zinc dust powder was dissolved in nitric acid, adjusted pH with NaOH and hydrothermally treated at 120-170°C in an oven. The resultant products were characterized for phase, surface area and morphology by X-ray diffraction (XRD), Brunauer-Emmet-Taller (BET) and Scanning electron microscopy (SEM), respectively. Moreover, the photocatalytic activity was investigated by a photodegradation of methylene blue solution under black light irradiation. It was shown that crystallinity of pure ZnO phase, was influenced by solution and hydrothermal treatment temperature. The experimental results exhibited that the crystallinity of ZnO significantly affected its photocatalytic activity. The highest photocatlytic activity was obtained from powders with average crystallite size of 51 nm and surface area of 13.4 m2/g prepared under pH12 and hydrothermally treated at 170°C for 6 h. Moreover, the synthesized ZnO powders performed a good antibacterial activity evaluated using a colony count method with Escherichia coli under the dark condition.

Characterization of (Ti,Al)N Thin Film Coated by PVD Cathodic Arc Using TiAl Target

Sintered TiAl alloy with composition of 50 at.% Al and 50at.% Ti are used as target in the PVD cathodic arc system to produce (Ti,Al)N film. The coating conditions are operated using substrate bias voltage and arc current bias of 100V and 70 A, respectively. In addition, the coating time was set at 1.30 h with thru different values of nitrogen gas pressures: 1, 1.5and 2 Pa. After coating the film was characterized for thickness, surface roughness, adhesion, morphology, and phase structure. It was found that phase structures, film thicknesses and adhesion of the films deposited from different nitrogen pressures are not significantly different. However, the micrographs showed that the film prepared by using 1.5 Pa of reactive N2 gas is smoother with less droplets than those film prepared at the other two pressures.

Preparation, Characterization and Catalytic Performance of ZnO-SBA-15 Catalysts

The series of ZnO-SBA-15 catalysts with 0.9wt% to 8.5wt% ZnO content have been synthesized by solvothermal impregnated of Zn acetate in ethanol on mesoporous silica SBA-15 platelets in order to maximize the methyl ester selectivity in transesterification reaction. The properties of these catalyst were characterized by N2 adsorption-desorption isotherm, NH3 temperature-programmed desorption, SEM, and XRD. The results showed that the ordered mesoporous structure of SBA-15 was remained with specific surface areas above 500 m2/g and a narrow pore size distribution observed with the mean pore size around 60 Å after ZnO modification. The strength of the acid sites and total acid amount of ZnO-SBA-15 catalysts is varied with number of ZnO loadings. The synthesized ZnO-SBA-15 catalyst was tested for catalytic activity in transesterification of crude Jatropha oil. It was found that at 200 °C for 2 h reaction of the ZnO-SBA-15 catalysts with acid capacities of 0.36-1.29 mmol H+/g-catal gave 68-98wt% of FAME yields and 0.4-1.4wt% of FFA yields which are comparable to the pure ZnO.

The Characteristic of Inner Surface Coating on Porous Al2O3 Tube by Electrophoretic Deposition

The nano-porous Al2O3 layer was performed onto inner surface of micro- porous Al2O3 tube by using electrophoretic deposition (EPD). Initially, Polypyrrole (Ppy) was applied on inner wall of tube to make conductive surface. The Al2O3 deposition was carried out in Al2O3 suspension with 5 wt % solid content in ethanol medium system using various applied voltages. Thickness of the deposited layer depends on applied voltages, after sintering at 1400oC the morphology of the deposited layer was investigated by FE-SEM. The good deposited surface without cracks and peeling has been prepared under applied voltage condition of 10 V.

Effect of Silica Base Catalyst on Transformation of Methanol to Hydrocarbon

Five different types of silica catalyst (SBA-15, SBA-15-PO3H2, and three different Si/Al ratio of commercial zeolites (30, 80 and 280) were used to study the transformation of methanol to hydrocarbon (MTH). The aim of this study was to investigate the effect of pore diameter and acidity in the structure of silica catalysts on the process performances in terms of methanol conversion and hydrocarbon selectivity. The mesoporous silica catalysts were prepared by co-condensation method. The catalysts samples were characterized by GC-MS, XRD, BET, and NH3-TPD techniques. The catalytic performance of synthesized and commercial catalysts for MTH process was evaluated using a homemade fixed bed reactor at temperature (300°C). It was found that the liquid hydrocarbon product provided by zeolite catalysts is aromatic hydrocarbons-rich. High Si/Al zeolites with larger pore size lead to higher selectivity and yield to paraffins (C1-C7). In contrast to commercial zeolite catalyst, SBA-15 and its modification with phosphorus species showed no conversion under studied condition. These results indicate that both pore diameter and acidity influence the product distribution in methanol to hydrocarbon process.

High Performance Ag/AgBr/TiO2 Photocatalyst-Coated Silica Beads

A series of three-component photocatalyst consisting of Ag, AgBr, and TiO2 were synthesized and successfully coated on PSB-01 beads (TiO2-coated silica beads). Different Ag to Ti molar ratios of 0.07, 0.10, and 0.20 in ethanol were prepared and coated on PSB-01 beads by sol-gel method. The morphologies and elemental compositions of these photocatalysts were characterized by SEM, EDS, and XRD, respectively. The performance of the photocatalyst coated on PSB-01 beads was evaluated in aspects of efficiency and stability. As for the photocatalytic efficiency, formic acid was used as the chemical model in this study. Results showed that the deposition of Ag/AgBr/TiO2 at Ag/Ti molar ratio of 0.07 on PSB-01 beads had the best performance in terms of formic acid degradation when compared to other ratios of Ag/AgBr/TiO2-coated PSB-01, Ag-coated PSB-01, and PSB-01 beads. In addition, for the study of stability, the release of silver from a series of Ag/AgBr/TiO2-coated PSB-01 was also evaluated.

Dispersion Stability of Drinking Water Treatment Sludge

The objective of this study is to improve the particle suspension stability of drinking water treatment sludge (DWTS) and comparable to other silicate powder which are bentonite, micro silica (micro-SiO2), and nano-silica (nano-SiO2). The main dispersion characteristic are related to particle size, and dispersion force. The representative samples of bentonite, micro-SiO2, nano-SiO2, and DWTS were dispersed at the same solid content in water. The particle size distribution and chemical composition of samples were analyzed. The suspended samples were measured for Zeta potential at the controlled pH value. Furthermore, turbidity of suspended samples were investigated at various sedimenting time. The results indicated that nano-SiO2 has the highest Zeta potential value at pH 8-12. The stability of particle dispersion could be implied from turbidity of suspension at various sedimenting time. Bentonite suspension performed more stability than other samples for longer time. However, stability of DWTS particles can be improved by particle size controlling and treatment with dispersion agent to create repulsive force from the charge on the particle surface.

Comparison of Pyrolysis of Jatropha Cake with Different Catalysts Using PY-GC/MS

In this work, effect of different zeolite catalysts that reacted with jatropha cake residue to give pyrolysed products was studied. The products were separated and characterised by using pyrolysis gas chromatography-mass spectrometry (PY-GC/MS). A 4.0 mg of jatropha sample was put into the capsule sample holder of the pyrolysis-GC-MS instrument and the pyrolysis was performed at 500°C. Two separate experiments were carried out. In the first experiment the catalysts were Mordenite zeolite (30 mol/mol ratio of SiO2/Al2O3), Beta zeolite (37 mol/mol ratio of SiO2/Al2O3) and Pd/Al2O3. Each catalyst was mixed with jatropha cake with a ratio of 1:1 by weight. The jatropha cake pyrolysed with Mordenite zeolite gave the highest amount of aromatic hydrocarbons and the lowest amount of fatty acids than the products obtained from the other zeolites. In the second experiment, the amount of Mordenite zeolite was optimised for maximum production of aromatic hydrocarbon. The jatropha cake was mixed with increasing ratios of Mordenite zeolite of 1:2, 1:3 and 1:5 by weight. Improving the ratio of the zeolite increased the amount of aromatic hydrocarbon, while the yield of phenol and fatty acids components significantly decreased. To study the interrelation effect between two catalysts to the pyrolysis of jatropha cake, Mordenite zeolite and Pd/Al2O3, were mixed with different ratios of 1:1, 2:1 and 3:1 by weight, and the jatropha cake was pyrolysed with the mixed catalyst at the ratio of 1:1. Increasing the ratio of Mordenite zeolite in the mixed catalyst gave similar effect to those without Pd/Al2O3, except that the phenol component in the product reduced. To obtain the highest yield of desirable components, namely aromatic and aliphatic hydrocarbons, Mordenite zeolite was proved to be the most suitable catalyst with the ratio of 1:5 by weight.