Synthesis of SnO2 and Zn doped SnO2 Nanoparticles by Flame Oxidation Process for Photocatalytic degradation of Methylene Blue Dye

A very simple and rapid flame oxidation method is effectively used to synthesis pure Tin Oxide (SnO2) and Zinc doped Tin Oxide (Zn:SnO2) nanoparticles from the metallic Tin (Sn) and Zinc (Zn) powders for the photocatalytic degradation of Methylene blue (MB) dye and characterized to study their structural, optical, elemental and chemical properties. From the X-ray diffraction analysis (XRD) it indicates that the synthesized SnO2 and Zn:SnO2 nanoparticles have pure tetragonal and cubical phases respectively and their average size increases when Zn was doped with SnO2. Raman spectral studies confirms the various mode of vibrations and the crystal structure of the synthesized nanoparticles from the spectral peaks of Raman shifts. Purity, atomic percentage and chemical composition were analysed using Energy dispersive X-ray analysis (EDX). The band gap energy was increasing from 3.5 eV to 3.6 eV when doping of Zn with SnO2, which was revealed from the UV-visible spectroscopic analysis. Photoluminescence analysis (PL) confirms the red shifted emission for Zn:SnO2 due to the oxygen deficiency. The CIE chromaticity(x,y) for SnO2 and Zn:SnO2 was calculated from the emission spectra and the cordinates represents blue and violet region respectively. Field Emission Scanning Electron Microscopy (FESEM) analysis shows that the pure SnO2 nanoparticles have irregular, agglomerated, nanoflowered and nanoclustered formation whereas Zn:SnO2 nanoparticles have more crystalline, cubical and nanoflakes structures. The photocatalytic activity was enhanced due to the presence of Zn in SnO2 under UV light irradiation. The efficiency of MB degradation by SnO2 and Zn:SnO2 nanoparticles are above 80%, which proves to be an effective photocatalyst.

“near wall” combustion model of spark ignition engine

This paper has illustrated a "near wall" combustion model for a spark ignition engine that was included in a two-zone thermodynamic model. The model has calculated cylinder pressure and temperature, composition, as well as heat transfer of fresh and combustion gas. The CO submodel used a simplified chemical equation to calculate the dynamics of CO during the expansion phase. Subsequently, the HC submodel is introduced, and the post-flame oxidation of un-burned hydrocarbon was affected by the reaction/diffusion phenomenon. After burning 90% of the fuel, the hydrocarbon reaction dominates at a very late stage of combustion. This modeling method can more directly describe the ?near wall? flame reaction and its contribution to the total heat release rate.