Abstract: Co-promoted Cu/ZnO catalysts were studied for Fischer-Tropsch synthesis (FTS). All catalysts were prepared by the co-precipitation method, having the mass ratio of Co:Cu:Zn=0 (unpromoted), 0.05, 0.5:1:1, and characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). From XRD and XAS, the results confirmed the phase transformation of CuO to Cu foil and Co3O4 to Co foil in Co-promoted catalysts after reduction. After FTS reaction testing, the Co-promoted catalysts showed the decrease in methanol selectivity of 15 and 1.6% for 0.05Co-Cu/ZnO and 0.5Co-Cu/ZnO, respectively, and the increase in C5-C15 selectivity during 30 h of reaction.
Abstract: The chitosan resin forming with commercial detergent solution was used as adsorbent for removal of the methylene blue. The effect of the amount of adsorbent was thoroughly investigated through batch adsorption system. The percent adsorption of methylene blue increased in the same direction as the amount of chitosan resin. The experimental result showed that adsorption capacity onto 0.4 g of chitosan resin was 9.1 mg/g. The Langmuir and the Freundlich adsorption isotherms were applied to describe the methylene blue uptake, which could be explained by Freundlich adsorption isotherm onto chitosan resin. Single-state batch adsorption design of methylene blue onto chitosan resin has been studied, using on the Freundlich isotherm equation.
Abstract: Non-isothermal DSC was used to study the cure kinetics of a flame-retardant benzoxazine resin system (BZ501-1) suitable for hot-melt prepreg preparation. The variation of activation energy with conversion for BZ501-1 system was investigated by using Flynn-Wall-Ozawa method, and the average value of activation energy obtained from this method was 100.5 kJ/mol. After that, the model function that depends on the reaction mechanism for the non-isothermal cure of BZ501-1 system was determined by Málek method, and the result showed that Šesták-Berggren model can generally simulate well the reaction rate. Finally, the isothermal curing behavior of BZ501-1 at 200 °C was predicted by using the obtained rate equation, and the result showed that there was no significant difference between the experiment conversions and the predicted ones. The predicted results at different temperatures indicated that the curing rate increased gradually with increasing the curing temperature.
Abstract: The dilute acid hydrolysis of fiber sago with cloride acid was undertaken in a microwave reactor system. The glucose and morphology analysis were performed after cellulose and hemi-cellulose hydrolysis. The hydrothermal condition was setup in a microwave furnace at microwave power of 800 W for 30-60 min. Scanning electron microscopy (SEM) analysis were utilized to confirm the microstructural changes after pretreatment. The results show that by using microwave energy, hydrolysis is not only can work in lower temperature than that of hot plate hydrolysis but also give a higher yield. There also found that the pretreatment optimum conditions for fiber sago hydrolysis is at 5% chloride acid solution and applied microwave power of 800 watt for 45 minutes. At that condition, there was found that sugar degradation occurred at acid concentrations greater than 30.15%. Microstructure evaluation from SEM photos shows that the disruption of the structure of the cell wall increases the accessibility of cellulase to lignocellulose. This results suggest that microwave technology is appropriate technology for holocellulose (cellulose and hemi-cellulose) hydrolysis.
Abstract: N-ZnO thin layer is widely used in application of wastewater photo catalyst. N-ZnO thin films have been successfully deposited on glass substrate using spray coating technique at 450 °C with varying concentrations of N from Urea source. XRD test results showed that the N-ZnO has a polycrystalline structure with diffraction field (100), (002), (101) and (110). The presence of nitrogen atoms in the lattice of ZnO causes a shift in diffraction angle between 0.08o - 0.18o. N-ZnO thin layer showed the occurrence of tensile strain. Surface morphology of N-ZnO is shaped like mine (like root). All samples have band gap energies lower than that of ZnO and the smallest is sample N6 with Eg = 3.249 eV. The presence of nitrogen atom increases surface roughness and decreases band gap energy.
Abstract: A series of experiments is made to produce silica, mixing with tin dioxide (SnO2), and characterizing for application of waveguide device. Silica xerogels (SX) are prepared from raw materials derived from rice husks ash (RHA), which abundant in South East Sulawesi. The synthesis conditions have been optimized to obtain the ash of rice husks with the maximum silica content. SnO2 are prepared from a commercial powder. The ceramic waveguide materials are produced by mixing SX and SnO2 with various composition. The mixtures are molded to form the rectangular shape of 20 mm, 40 mm, and 5 mm in size. The samples will be sintered at different level of temperatures (from 300°C to 1200°C) by using microwave heating system as well as electric furnace. The microstructural of sintered samples were characterized on the basis of the experimental data obtained using densification measurement method (Archimedes method), crystallization (X-ray diffraction, XRD), microstructure (Scanning electron microscope, SEM). Optical and related properties such as the functional groups, structure, and absoption were characterized by using FTIR, Infrared and Raman Spectroscopy and absorption (UVVis). The permittivity and permeability will be calculated from S-parameters determined by using Vector Network Analyzer (VNA). Characterization results are presented in this paper and the others are will be published in another separated papers. Furthermore, the relationship between properties with SnO2 content and sintering temperature is also studied.
Abstract: In this study, attempt has been made to investigate the effect of SiC particles on the friction and wear properties of Ni/SiC composites manufactured by electrodeposition, especially for the composites with high-temperature treatment.For this purpose, α-Al2O3 was coated on the surfaces of SiC particles by sol-gel technology to inhibit interfacial reaction of SiC and nickel at high temperature. Both of the Ni/α-Al2O3-coated SiC (Ni/CSp) and Ni/uncoated SiC (Ni/UCSp) composites were treated at 600 °C to study the resulting wear behaviour. The results indicated that with heat treatment at 600 °C, the Ni/CSp composite had better tribological properties than the Ni/UCSp composite. It was proved that the uncoated SiC particles have reacted completely with nickel leaving many defects, while the coated SiC particles still remained in the Ni/CSp composite hardening the nickel matrix and supporting the counterpart, thus improving the wear resistance of Ni/CSp composite with relatively low friction coefficient and wear mass loss compared to the Ni/UCSp composite.
Abstract: While performance and durability are the key features of any Material behavior, the greater the elasticity and flexibility ability the better the functioning capabilities. These Material functioning capabilities not only include improved Load Bearing Capacity (LBC), but also enhanced stress and strain abilities. In addition, these functioning capabilities are dependent on composition of the material, Total Load (TL) and Design specification requirements. A key mechanical behavior of materials is their Viscoelastic ability. While Viscous materials are objects that become deformed via shear and tensile stresses, elastic materials are those that change their shape under stress and strain. Furthermore, Viscoelastic materials are those which portray both elastic characteristics as well as viscous behavior when enduring deformation. This Viscoelastic ability is a critical factor for materials to be effectively Total Load (TL) resistant. Accordingly, this paper will discuss some of the more important Material innovation, and development countenances such as functionality to further demonstrate the overall Viscoelastic behavior.
Abstract: Mixing behaviors of the compounds filled with different reinforcing fillers were studied in correlation with compound and vulcanizate properties. Four filler systems were used including: 1) silica plus small amount of silane coupling agent; 2) carbon black; 3) pre-modified silica; and 4) silica+silane-carbon black mixed one. The results have shown that silica provides longer optimum cure time and shorter cure rate than carbon black due to accelerator adsorption on silica surface. In addition, owing to highly polar nature on silica surface the silica-based compounds show rather high viscosity, attributed to stronger filler-filler interaction as can be confirmed by Payne effect and reinforcement index. However, the commercial surface treatment or pre-modified form of silica shows superior properties than in-situ modification of silica by silane during mixing, while it gives comparable properties to carbon black-based compound. Tensile properties of vulcanizates show a good correlation with the basic properties of their compounds.
Abstract: Transition metal oxides and hydroxides, specifically nickel (Ni), are currently being studied for their pseudocapacitive behaviors due to their high specific capacitance and efficient redox reactions. In this study, nickel oxide (NiO) and nickel hydroxide [Ni (OH)2] hierarchical structures were grown on carbon fiber paper via hydrothermal treatment for a binder-free electrode for pseudocapacitor. Cyclic voltammetry was employed to determine the influence of annealing temperature on the specific capacitance of NiO-and/or Ni (OH)2 – carbon fiber electrodes. The NiO – carbon fiber electrode annealed at 400°C exhibited the highest specific capacitance of about 1993.12 F/g at a scan rate of 2 mV/s. The carbon fibers were fully covered by NiO platelets which possibly provide efficient transport of electrolyte, enhancing the capacitance.