nan Yunardi

Visible Light Driven Photocatalytic Hydrogen Evolution by Lanthanum and Carbon-co-Doped NaTaO3 Photocatalyst

Lanthanum and carbon co-doped sodium tantalum oxide, La-C-NaTaO3, are prepared by incorporating lanthanum and carbon into NaTaO3 cluster via a sol-gel technique using a sucrose as carbon source. The La-C-NaTaO3 prepared sample is calcined at a temperature of 700 °C. Effects of carbon contents on the crystal, shape, optical absorption response and activity of hydrogen production of the sample are evaluated. The crystal of La-C-NaTaO3 is characterized by XRD analysis. The results show that the XRD pattern of the La C co-doped NaTaO3 is found to be crystalline phase with monoclinic structure. From the analysis of SEM images, the particle size of the prepared powder is about 40-200 nm. The optical response is examined by diffuse reflectance spectra (DRS). It is depicted that the absorption edge of La-C-NaTaO3 crystalline shift to higher wavelength. The extension to the visible light absorption edge became drastic with increasing carbon content in the sample. The photocatalytic activity of La-C-NaTaO3 is examined from water-methanol aqueous solution under visible light irradiation. It is found that the photocatalytic activity of La-C-NaTaO3 depend strongly on the doping content of C, and sample La-C-NaTaO3 shows the highest photocatalytic activity for the water reduction. The optimum amounts of carbon to maximize the hydrogen evolution rate is to be 2.5 mol %. The La-C-NaTaO3 catalyst has high activity of H2 evolution of 40.0 [μmol h-1] and long time stability under visible-light irradiation, suggesting a promising utilization of such photocatalyst. La C co-doped NaTaO3 photocatalyst can be developed further in order to produce hydrogen as a green energy.

Simulation of the Influence of Air Preheat Combustion on the Temperature of Propane Turbulent Flame Using Probability Density Function Approach and Eddy Dissipation Model

This paper presents results obtained from the application of a computational fluid dynamics (CFD) code Fluent 6.3 to modelling of temperature in propane flames with air preheat. The study focuses on investigating the effect of air preheat temperature on the temperature of the flame. A standard k-ε turbulence model in combination with the Probability Density Function (PDF) model for Non Premix Combustion model and Eddy Dissipation Model (EDM) are utilized to represent the flow and temperature fields of the flame being investigated, respectively. The results of calculations are compared with experimental data of propane flame taken from literature. The results of the study showed that the combination of the standard k-ε turbulence model and PDF model is more capable of producing reasonable predictions of temperature, particularly in axial profile and rich fuel area of all two flames compared with those of EDM model. Both experimental works and numerical simulation showed that increasing the temperature of the combustion air significantly increases the flame temperature.