Sirithan Jiemsirilers

Effects of Surface Treatment on Adhesion of Silver Film on Glass Substrate Fabricated by Electroless Plating

Silver film was fabricated on a glass substrate by electroless plating technique. Plating solution, which also known as Tollen’s reagent, consisted of three main solutions: silver nitrate solution as a silver source, ammonia and sodium hydroxide as pH controllers and D-glucose as a reducing agent. Glass surface was treated by three different methods: HF etching, SnCl2 activation and SiC paper grinding. After that, a glass slide was immersed in plating solution for 90 minutes at a room temperature. The purpose of this work was to study the effects of different surface treatments on adhesion between substrate and film. X-ray diffraction (XRD) pattern confirmed that the obtained film was a silver phase. Surface morphology of glass slides, before and after plating was investigated by scanning electron microscope (SEM). Moreover, the adhesion of silver film to glass substrate was performed by crosscut test and it was indicated that combined treatment by SiC paper grinding and HF etching was the best surface treatment which provided a good adhesion of film to substrate.

Effect of MSW Incineration Bottom Ash in Clay Based Ceramics

The clay-based ceramic was produced by adding with the bottom ash from domestic municipal solid waste incinerator plant in Thailand. The amount of the ash up to 60 wt% was added. The samples were dry pressed and sintered at the temperature range between 1000 and 1125°C. The presence of quartz (SiO2), anorthite sodian (Ca,Na)(Si,Al)4O8, albite (Na(Si3Al)O8) and mullite (Al6Si2O13) was observed in the sample with the addition of the bottom ash. The physical and mechanical properties were also presented. The sintering temperature and the ash addition revealed the effect on the properties of the product.

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.

Hydroxyapatite nanoparticles formed under a wet mechanochemical method

Hydroxyapatite (HA) nanoparticles were synthesized using a wet mechanochemical method without a calcination process. Dicalcium phosphate dihydrate (CaHPO4 ·2H2 O) and calcium carbonate (CaCO3 ) were mixed and milled in a planary mill using ethanol or water as liquid media in the two different synthesized routes. Effects of rotation speed and milling time on the final products formed have been studied. Experimental results showed that HA phase having a characteristic of low crystallinity could be formed under the synthesis route using water. The original phases of both starting chemicals were remained without HA formation in the synthesis route using ethanol. Particle size and morphology of HA nanoparticles were obviously depended on optimum conditions of rotation speed and milling time. Differences on phase formation in both synthesized routes have been considered and discussed based on occurring chemical reaction possibilities.

Influence of Alkaline Concentration on Physical Properties of Porous Geopolymer Using Silica Fume as Foaming Agent

Porous geopolymer could be synthesized by using metakaolin and silica fume as foaming agent. The foam morphology was estimated in the function of water, silica fume content, and curing temperatures. Raw materials were mixed by Hobart mixer for 5 minutes and then poured in to cylinder mold after that cured at 70 degree celsius for 24 hours. During the synthesis process, the complex reaction would occur such as polycondensation and oxidation. These reactions affect to chemical and physical properties of porous sample. The parameters that mention above affect to density, physical, and chemical properties. The thermal conductivity of porous geopolymer that contained with 14 molal NaOH concentration yield the lowest values of 0.5101 W/mK and pore size distribution of 0.01-0.8 mm.Keywords: Porous geopolymer, thermal conductivity, metakaolin

Inner Surface Coating of Non-Conductive Tubular Substrate Using Electrophoretic Deposition

Inner surface of microporous alumina tube was coated with nanoporous alumina layer using electrophoretic deposition (EPD) process. Polypyrrole (Ppy) film was formed on the inner wall of the porous tube to give electrical conductivity by chemical polymerization of pyrrole (Py). The nanoporous structure was controled using bimodal suspension of alumina powders with 0.6 μm and 30 nm in ethanol. The thickness of the coated layer was controlled by varying the processing parameters such as deposition time and DC applied voltage. After the deposition, the coated substrate was sintered at 1250°C for 2 h to bond the coated layer with the substrate.The microstructure of the substrate and the coated layer was observed by SEM. The results show the good interfacial joining between the substrate and the coated layer; they are not seperatated after the Ppy burnt-out. Crack-free and nanoporous layer on the microporous substrate was successfully fabricated.

Synthesis and Sintering of Magnesium Aluminate Spinel Nanopowders Prepared by Precipitation Method using Ammonium Hydrogen Carbonate as a Precipitant

Magnesium aluminate spinel (MgAl2O4) is widely used in many engineering applications due to its high melting point (2135°C), high mechanical strength, chemical inertness, and good optical properties. Precipitation method is recognized as a convenient and cost-effective method for the synthesis of nanopowders. In this present work, MgAl2O4 nanopowders were prepared by precipitation method using ammonium hydrogen carbonate as a precipitant. The precipitated precursors were a mixture of ammonium dawsonite (NH4Al (OH)2CO3·H2O) and hydrotalcite (Mg6Al2(CO3)(OH)16·4H2O). After calcining at 1100°C for 2 hours, The MgAl2O4 nanopowders with particle size of 20-170 nm were obtained. The sinterability of the MgAl2O4 nanopowders was evaluated by sintering compacts of the MgAl2O4 nanopowders at temperature of 1300-1650°C for 2 hours. The relative density of the sintered MgAl2O4 ceramics reached about >97% of theoretical density after sintering at 1500°C for 2 hours. The Vicker’s hardness of the sintered ceramics reached a value of 1414 HV (13.9 GPa) after sintering at 1650°C for 2 hours.

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.

Metakaolin Based Geopolymer from Thailand as an Adsorbent for Adsorption of Multi- and Mono- Cations from Aqueous Solution

Waste management and water quality are two main problems nowadays. Geopolymer material has efficiency for adsorbing the ions from wastewater. In this research, the metakaolin based geopolymer was studied and used as an adsorbent to remove heavy metal ions. Moreover, the factors which affect adsorption process of heavy metals on geopolymer materials were investigated. The kaolin as used in this research was from Thailand. The metakaolin geopolymer was synthesized by mixed raw materials with an alkaline solution. The metakaolin geopolymer was washed and sieved through 100 mesh. The produced metakaolin geopolymer powder was used as an adsorbent. The XRD results showed a highly amorphous structure in obtained metakaolin geopolymer. Moreover, the BET surface area of metakaolin and geopolymer particles were 9.83 m2/g and 20.36 m2/g, respectively. The parameters of adsorbent amount, initial pH, time of shaking, temperature and initial metal ions concentration on the removal potential of geopolymer were studied. In addition, the multi-and mono-cations solution were demonstrated to compare the efficiency of each heavy metal ions. The results showed that the amount of Pb2+, Cu2+, Cd2+, and Ni2+ ions adsorbed onto metakaolin geopolymer increased with an increasing contact time, pH, temperature and amount of geopolymer. It is concluded that Pb2+, Cu2+, Cd2+, and Ni2+ ions in aqueous solution are efficiently removed by metakaolin geopolymer which could be applied as a low cost and good alternative for wastewater treatment.

Removal of Pb2+, Cu2+, Ni2+, Cd2+ from Wastewater using Fly Ash Based Geopolymer as an Adsorbent

This work aims to evaluate the effectiveness of fly ash based geopolymer powder as an adsorbent for heavy metals in aqueous solution. The structure of synthesized geopolymer was found to be highly amorphous due to the dissolution of fly ash phase. Moreover, the fly ash geopolymer powder has higher surface area compares to original fly ash with specific surface area of 85.01 m²/g and 0.83 m2/g, respectively. For this reason, the geopolymer powder has much higher removal efficiency compared to the original fly ash powder. The removal efficiency was affected by contact time, geopolymer amount, heavy metal initial concentration, pH, and temperature. The four heavy metals were chosen (Pb2+, Cu2+, Ni2+, Cd2+) for adsorption test. The highest heavy metal removal capacity was obtained at pH 5. The geopolymer powder adsorbed metal cations in the order of Pb2+>Cu2+>Cd2+>Ni2+. In addition, Langmuir model is more suitable for fly ash geopolymer powder adsorption of heavy metal ions in aqueous solution than Freundlich model. The results showed that the fly ash geopolymer powder has high efficiency for removal metal which could be employed excellent alternative for wastewater treatment.