Advanced Materials Research Vol. 1087

Abstract: The priority of success in practical CO₂ capture with solid sorbents is dependent on the development of a low cost sorbent and energy consumption for regeneration with high adsorption capacity. In this work, different loading of NiO were evaluated as a potential source of basic sites for CO₂ capture, and activated carbon (AC) was used as a preliminary support in order to study the effect of the impregnation. The NiO loading increased the basicity of the adsorbent significantly enhance the CO₂ chemisorption. Nonetheless, it drastically reduced the surface area of the AC, which is chiefly responsible for CO₂ physisorption, thus decreasing the carrying capacity of ACs at room temperature and pressure.

Abstract: CaCu_(3+x)Ti₄O₁₂ (CCTO) ceramics with different Cu-excess (x = 0 – 0.6) were prepared by conventional solid-state reaction method. Characterization of the prepared ceramics with XRD and FESEM showed that lattice parameter and grain size are slightly increased, indicating Cu-excess to have the big impact on the both phase structure and microstructure. The XRD profiles indicated that the secondary phase (CuO or Cu₂O) existed at edge/corner of CCTO grain, which promoted inhibited grain growth behavior. The CCTO ceramics exhibited two trends of dielectric constant related to frequency, which showed a flatter curve about ~50 in 1 – 25 GHz regions, and it’s dropped rapidly to ~35 in 25 – 50 GHz region. With Cu-excess, the dielectric constant of the ceramics was increased for an average of a quarter-order of magnitude, while the tangent loss also increased up to triple times than x = 0, for the same frequency range. Despite enormous increase of dielectric constant related to varying Cu-excess, the tangent loss also increased.

Abstract: Reduction of Fe₂O₃ by carbon monoxide (CO) have been studied by temperature programmed reduction (TPR) and X-ray diffraction spectroscopy (XRD). The influences of carbon monoxide concentration on the reducibility of iron oxides have been investigated. This study deals with the comparison in the reduction of Fe₂O₃ between 5% to 20% of CO concentration in the temperature range of 40–900 °C. The result shows that reducing behaviour of Fe₂O₃ is strongly dependent on the concentration of CO. It is suggested by using 20% of CO complete reduction takes place at lower temperature due to absence of intermediate FeO giving only two-steps reduction (Fe₂O₃ → Fe₃O₄ → metallic Fe). Moreover, excess of CO results the formation of iron carbide phase.

Abstract: The crystal structures of two fused pyridine derivatives viz Ethyl 3-amino-6-phenyl-4-tolylfuro[2,3-b]pyridine-2-carboxylate (I) and Ethyl 3-amino-6-phenyl-4-tolylthieno[2,3-b] pyridine-2-carboxylate (II) were optimized by semi-empirical methods using MOPAC2009 program. The geometries optimized for both the structures from Austin Model 1 (AM1) and Parametrization Model 6 (PM6) describe the conformational discrepancy and crystal packing effects. The parametric molecular electrostatic potential (PMEP) calculated by AM1 semi-empirical method describe the involvement of nitrogen and oxygen atoms in the crystal packing interactions in both the structures. The frontier molecular orbitals highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) indicate the intramolecular charge transfer interactions. The HOMED indices computed for the phenyl rings in the structures describe the p-electron delocalization. The linear regression analysis shows good correlation between experimental and theoretical structures.

Abstract: A metallic molybdenum is formed by a two-stage process that was carburized MoO₂ with carbon monoxide followed by heat treatment. XRD techniques were employed to identify the phase’s changes in the sample. It was found that by the present of carbon monoxide during carburization process until 900 °C, Mo₂C is formed first, compared to metallic molybdenum, due to the high thermodynamic barrier for formation of metallic molybdenum. In the second stage, Mo₂C further reacts with the remaining MoO₂ at 900 °C to produce metallic molybdenum.

Abstract: Metal foams had been developed years ago by researchers. There were various methods used to produce metal foam such as slurry, compaction, gas entrapment technique and casting methods. In this study, slurry method used to produce SS316L foam with powder compositions 50wt%, 55wt% and 60wt%. Polyethylene Glycol (PEG) and Carboxyl Methyl Cellulose (CMC) were used as binder which was mixed with SS316L powder and distilled water. Polyurethane (PU) foams were impregnated with slurry by pressed out to cover every pores and struts of PU foams. Then, the coated PU foams were dried in the oven for 24 hours at 30°C, followed by sintering process in the vacuum furnace at three different temperatures which were 1200°C, 1250°C and 1300°C. There were Oxygen, Aluminium, Calcium, Silicon, Chromium, Nickel, Ferrous and Molybdenum elements found in the SS316L foams.

Abstract: Tungsten (VI) oxide (WO₃) reduction by carbon monoxide were examined using temperature-programmed reduction (TPR) and X-ray powder diffractometry (XRD) studies. Results show that WO₃ start to reduce at 20% (CO in N₂) at temperature 900 °C and the intermediate phases WO_2.9 and WO_2.83 were observed. The WO₃ was reduced and transformed the completely to the WO_2.72. As comparison, reduction by using 10% (H₂ in N₂), WO₃ was reduced completely toWO₂. The WO₃ is a stable oxide because the reduction agent used to promote the reduction was not sufficient enough to reduce to zero metal tungsten.

Abstract: The eggshell waste which has potential mineral such as calcium oxide (CaO) was studied for biomass pyrolysis in a fixed bed reactor. The objective of this study was to characterize the CaO from waste eggshell and correlated the potential in pyrolysis process. Raw eggshells were analyzed by thermal gravimetric analyzer (TGA). Then, they were calcined at the temperature of 900^oC for 1 hour with nitrogen gas. Raw and calcined eggshell were characterized by x-ray fluorescence (XRF). Non-catalytic and catalytic pyrolysis were done in the optimum pyrolysis condition with eggshell as a catalyst. XRF results showed that the percentage of CaO in raw eggshell was increased in calcined eggshell. Bio-oil product yield increased by 25.98% by using eggshell waste as a catalyst. CaO from waste eggshell improved the production of bio-oil in terms of quantity.

Abstract: Anodic oxidation (AO) is a chemical method which used to produce a bioactive layer (oxide) of titanium (Ti). The aim of this study is to evaluate the effect of anodic oxidation upon Ti foil in acetic acid (C₂H₄O₂). The anodic oxidation was performed by varying the applied voltage (10 – 200 V) and concentration of the electrolyte (0.5, 1.5 and 3.0 M of C₂H₄O₂). After anodic oxidation, the Ti specimens were soaked in simulated body fluid (SBF) to observe the precipitation of hydroxyapatite (HAP). The Ti sample was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) after anodic oxidation and SBF. The precipitation of apatite after soaked in SBF was observed using SEM. From this study, the applied voltage range from 100 to 200 V at low and high concentration of acetic acid resulting in the porous surface of anatase. The arcing process occurred during the oxidation process which lead to the formation of anatase and sites for HAP growth (nucleation site). The SBF result shows that the anodised Ti is suitable to be applied in biomedical especially as implant.

Abstract:

Powder metallurgy stainless steels are retains unique benefits in preparation of porous metals due to its low cost, better wear, precise size control and corrosion resistance which are significant quality displays. In this study, the fabrication of open cellular stainless steel (SS316L) foams by using a crystalline sugar via compaction method was investigated. In this work, we show a promising method of SS316L preparation with crystalline sugar as space holder particles. Then, the foams will be given to consider the properties of SS316L foam after sintering process. Powder metallurgy process needs to go through the mixing, pressing, sintering and analysis. The selected composition of SS316L was 50 wt % and 55 wt % SS316L while the remaining percentages are foaming agent or binder. Then, sintering process was conducted in the tube furnace. The SS316L foams were characterised using X-Ray Diffraction (XRD) and Energy Diffraction X-ray (EDX). The results of this study indicate that, the XRD was detected Austenite stainless steel. Then, the detected elements in the SS316L foam were O, K, Mn, Cr, Fe, Mo and Al.