UniMAP Conference and Proceedings
Permanent URI for this collection
Browse
Recent Submissions
1 - 5 of 247
-
PublicationAnalysis of particle size and XRD in ZnO-based varistor(Universiti Malaysia Perlis (UniMAP), 2010-09-06)ZnO varistors doped with Bi₂O₃, Sb₂O₃, CoO, MnO₂ and Cr₂O₃ were prepared separately by two mixing processes: conventional and masterbatching mixed-oxide process method. After the mixing process, the ZnO-based varistor powders were milled using planetary ball mill at 200, 300, 400 and 500 rpm. Particle size analysis and XRD analysis were used to study the differences after milling process in ZnO-based varistor powder. The particle sizes of varistor powder were reduced and new compound encountered after milling process.
-
PublicationSelective oxidation of glycerol over titania supported AuPd bimetallic catalysts(Universiti Malaysia Perlis (UniMAP), 2010-06-09)Oxidation of glycerol to form various types of important short chain oxygenated derivatives became an important reaction to support biodiesel industries. In this study, a series of AuPd nanoparticles at different metal ratio which were 9:1 and 8:2 supported on titania (TiO₂) were successfully prepared, characterized and tested for its activity and selectivity in liquid phase oxidation reaction of glycerol. All the catalysts were prepared by deposition-precipitation method with decomposition of urea agents. AuxPdy/TiO₂ catalysts were characterized using XRD, TEM and XPS. The formation of alloy Au-Pd phase was ascertained by XRD and XPS analysis. TEM analyses have shown that the Au and Pd metal particles in the range of 10-30 nm in size were uniformly dispersed on the TiO₂ support with narrower size distribution. Higher catalytic activity observed for the catalysts was attributed to the presence of metallic Au0 and PdO phases together with the ‘synergistic’ effect of Au-Pd alloy. The highest selectivity to tartronic acid (54.6%) was obtained by using Au₉Pd1/TiO₂ catalyst after 8 h of reaction time at lower reaction temperature (50⁰C).
-
PublicationStructural property, surface area and electrical conductivity activated carbon from biomass materials and various manufacturer in Malaysia(Universiti Malaysia Perlis (UniMAP), 2010-06-09)The activated carbon from biomass sources has been widely used for industrial application because it has a superior electrical conductivity and high absorption properties. This paper presents the electrical conductivity property and the relation between structural parameters from X-ray diffraction technique and BET surface area of various activated carbon materials. There are six activated carbon powders were collected from difference local manufacturers. These samples were characterized by electrical conductivity measurement, N2-gas adsorption analysis and structural property from X-ray diffraction analysis. Measurement on powder activated carbon shows that the highest electrical conductivity value is SC sample with the value of 3.484 (Ωcm)-1 from coconut shell. The SC sample also has the lowest value of thickness of graphitic microcrystallites, Lc. This study demonstrates that activated carbon from coconut shell has the highest electrical conductivity value compared to oil palm shell activated carbon.
-
PublicationPreparation and characterisation of TiO₂ thick films fabricated by anodic oxidation in sulphuric acid(Universiti Malaysia Perlis (UniMAP), 2010-06-09)Anodic oxidation is an electrochemical method for the production of oxide films on metallic substrates. It involves the application of an electrical bias at relatively low currents while the substrate is immersed in an acid bath. The resultant oxide films can be very dense and stable, showing a variety of colours and microstructural characteristics. In the present work, thick films of the anatase and rutile polymorphs of TiO₂ were formed on highpurity Ti foil (50 m thickness) using sulphuric acid solutions (1.5 M H₂SO4). The conditions of oxidation involved the application of potentials (5 to 350 V) and current densities (5 to 60 mA.cm-2) for 10 min at room temperature. The films were characterised using a digital photography, laser Raman microspectroscopy, and field emission scanning electron microscopy (FESEM). The thicknesses of the oxide films on Ti were measured using a thin film analyser based on optical spectroscopy principles. The phase formation, colours, thicknesses, and microstructures of the films depended strongly on the applied voltage and current density. At a standard bias of 150 V, single-phase anatase was observed to form on Ti at low current density (5 mA.cm- 2) but, at higher current densities (up to 60 mA.cm-2), increasing rutile formation was observed.
-
PublicationNew silica supported HClO₄ as an efficient catalysts for the estolide synthesis from oleic acid(Universiti Malaysia Perlis (UniMAP), 2010-06-09)The synthesis of estolides via condensation reaction of oleic acid were investigated using heterogenous and homogenous catalysts. The condensation reaction usually carried out by using of various acids catalysts, such as H₂SO₄, H₃PO₄ and HClO₄. HClO₄ is highly toxic, give a major problem to cleaner technology and cause severe corrosion problem. In this studies HClO₄ could be made environment friendly catalyst by supporting onto suitable supports. A series of the solid acid catalyst containing 5-45 % of perchloric acid supported onto silica was synthesized. All amorphous material catalysts were characterized using XRD, BET surface area measurement, TEM and XPS surface analysis. Silica modified with perchloric acid has been found to be efficient and environmentally benign solid acid catalyst for estolide synthesis. The reaction has been performed for 10 hours at 70⁰C to give oleic-oleic monoestolide acid, m/z 563.51 as (M - H) -. The solid acid catalyst is easily separated from the reaction mixture. Based on the experimental findings above, catalytic performance was optimized with loading 15 % HClO₄ onto SiO₂. These catalyst was HClO₄ on silica gave 98.98 % conversion with 63.98 % oleic-oleic monoestolide acid, m/z 563.51 (M-H) - selectivity. The similarities between homogenous and heterogenous acid-catalyzed are also discussed.