Key Engineering Materials Vol. 860

Abstract: Electrospinning is a method for making nanofibers by utilizing an electric field produced by high voltage. Electrospinning process is influenced by several factors including the concentration of the solution, conductivity, viscosity, volatility, surface tension, electric field strength between the needle and the collector, feed / flow rate and environmental conditions which include temperature, humidity and air composition. Electrospinning parameters are used to optimize the size of the nanofiber, concentration of the solution and the distance of the nozzle to collector. In the process of electrospinning PVA solutions that are handled by high dc voltage gets an electrostatic force and electric field. The solution will elongate to form a Taylor cone, then a jet of polymer will undergo thinning and evaporation to form fibers in the collector. The results of morphological analysis using scanning electron microscopy (SEM) showed that the smallest nanofiber was obtained at a solution concentration of 5%, dc high voltage10 kV, and the distance of the nozzle to collector was 15 cms.

Abstract: Composite of two phases with crystal grains of titanium nitride (TiN) and amorphous of silicon nitride (Si3N4) had shown an improvement of mechanical properties as shown by composite layer of nickel (Ni) and TiN. In this study, Ni-TiN/Si3N4 composite layer on tungsten carbide bar have been prepared by using electrodeposition to study the effect of current density on the microstructure and mechanical properties of the layer. The optimum properties of composite coating with no crack morphology and maximum hardness was shown by the sample electrodeposited at current density of about 2.5 mA/cm2. The high hardness was attributed to the nickel crystallite size refinement

Abstract: Aluminum doped ZnO crystal powders have been successfully prepared by sol-gel method with low temperature (150°C) crystallization process. The AlNO₃ as material dopant were varied by 0.5 wt% and 1.0 wt% relate to 5 mmol of zinc acetate dihydrate as precursor. Degradation of the methylene blue (MB) was used to evaluate the photocatalytic property. The results showed that all ZnO samples have spherical morphology with hexagonal wurtzite crystal structures. The ZnO powder with 0.5 wt % of aluminum has a better photocatalytic property that related to the optical characteristics. The optimum of Al content (0.5wt%) reduces the crystallite size and give some advantages in optical characteristics that directly relate to the increments in photocatalytic behavior. The photodegradation rate of Al doped ZnO 0.5 wt% is increase almost 100% compared with ZnO undoped. The stability and reusability of 0.5 wt% Al doped ZnO as photocatalyst, is also observed by monitoring the photocatalytic behavior under 14 hours irradiation (in three recycle used)

Abstract: This study explored adsorptive property of ceria nanocrystal as an adsorbent for amoxicillin removal from water. Ceria nanocrystal was synthesized by employing precipitation method and characterized by using XRD and N₂ adsorption-desorption analysis. The adsorption experiment was performed by managing amoxicillin in natural condition. Then, parameters in the adsorption experiment, such as adsorbent dosage, contact time, temperature and initial concentration of amoxicillin are varied. The XRD pattern illustrated that the average crystallite size of ceria nanocrystal formation was 13.08 nm. N₂ adsorption-desorption analysis showed that ceria nanocrystal was mesoporous with specific surface area of ​​65.26 m²/g. The amoxicillin adsorption of ceria nanocrystal adsorbent was described by Langmuir isotherm model with maximum adsorption capacity of 37.17 mg/g. The adsorption kinetic of ceria nanocrystal corresponded to the pseudo-second order model. Removal efficiency of amoxicillin by ceria nanocrystal was approximately 80% within 60 minutes over temperature range 303-323K. Those parameter results are described that ceria nanocrystal adsorbent is feasible as a rapid amoxicillin removal from water.

Abstract: Organic material produced from domestic food waste can be functionalized as useful product such as fish feed by fermentation process. The fermentation process changed several properties such as nutrition content and particle size. Here, we reported the effect of fermentation process on physical properties of organic material from domestic food waste. In this study, fermented product will be conducted to become fish feed. The fermentation was performed by using commercial probiotic BIOM-S with various levels of probiotic from 0 to 10% using solid substrate fermentation method. The physical properties including nutritional content, particle size, distance between particles, and functional group of fermented organic material from domestic food waste were investigated. After fermentation, it is found that the best level of probiotic use is 8%, which are crude protein increased from 15.58% to 26.16% and crude fiber content decreased from 4.88% to 3.71%. The average particle sizes and distance between particles of fermented domestic food waste fermented by 8% probiotic were 147.723 µm and 1708.802 µm, respectively, while the functional group did not change after fermentation. The present result indicated that fermentation process effected to improve the quality of organic material from domestic food waste.

Abstract: Carbon nanofibers (CNFs) have been successfully prepared by using electrospinning at various flowrates, and were formed from polyvinyl alcohol (PVA) and activated carbon (700-1400 m²/g) as electrodes on capacitive deionization. Before being furthermore deposited into electrodes, characterization was carried out on CNFs by using SEM. Cyclic voltammetry analysis was also performed to determine the electrolysis mechanism of the electrodes. The best results in removing salt reaching 70% were achieved by capacitive deionization systems with the smallest diameter size of CNFs, at a voltage of 1.5 V. The CNFs formed by electrospinning have potential to be used as excellent capacitive deionization electrodes for the desalination process.