Study of Spilled Oil Behavior on the Topsoil Induced by Thermal Diffusion

The fate and transport of oil spilled in soil has long been a focus for experimental and theoretical research in subsurface hydrology. Oil transport in the soil is affected by a large number of physical, chemical and microbial processes; and the properties of the media. This study is a two layer problem containing horizontal oil layer overlying the subsurface topsoil region saturated with oil and water (native fluid). To explain the method by which the convective flow in the oil region affect the transportation of oil, modeling is carried out in two regions (oil and topsoil). The two dimensional, transient oil flow equations for both the regions include thermal and concentration buoyancy effects. The species equations include the effects of energy flux caused by the temperature gradient on the unsteady advective-diffusion equation. The resulting fluid flow, heat and mass transfer processes are discussed numerically with the aid of graphs. The validity of the results obtained is verified by comparison with available results and good agreement is found

Mathematical model to study The spread of spilled oil in the soil

A mathematical model describing the spread of spilled oil through the soil is discussed. The spread of spilled oil in soil is controlled by the flow of water and is described by multiphase equations. In this context, the two-phase flow characteristics of oil-water flow with varying viscosity in the subsurface coupled to an advective-diffusion equation are examined to study the transport of oil. The terms that model the interaction between the multiple phases are introduced at the boundary, such as the slip condition at the porous-fluid interface, shear stress condition at the fluid-fluid interface, and the continuity of velocity at both the interfaces. The effect of various physical parameters such as Schmidt number, retardation factor, viscosity ratio, porous and slip parameter on the velocity and concentration profiles are discussed in detail with the help of graphs. The surface plots of velocity and concentration of oil against axial distance at different time are also analyzed. The obtained results show that the velocity of oil accelerates linearly with axial length and there is a decrease in the concentration of the spilled oil through the media. The validity of the results obtained is verified by comparison with available experimental result, and good agreement is found

Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

International audienceA TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP) and 2–propanol as a common starting material and the obtained products were calcined at 450˚C450˚450˚C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR). The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co 2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap