Reduction Of Interaction Energy Research Articles

The influence and mechanism of alkyl block polyethers on the interfacial tension and minimum miscibility pressure of CO2 and shale oil

The successful application of CO2 in developing shale oil can increase oil production and reduce CO2 emission. Reducing IFT and facilitating miscibility between CO2 and oil is the critical mechanism for enhancing shale oil recovery by CO2 flooding. Here, the effects of alkyl block polyethers on the interfacial tension and minimum miscibility pressure of CO2 and shale oil has been investigated by experiments and the influence mechanism of polyether on IFT and MMP has been explored by molecular dynamic simulations. The experimental results show that among the three polyethers, C4(PO)6 has the best effect to decrease the IFT and MMP of CO2 and shale oil. The IFT and MMP decrease with the increasing concentration of C4(PO)6 in CO2. The IFT and MMP can be decreased to a lower value when the polyether is dissolved in CO2 than in oil phase. The molecular dynamic simulations show that polyether molecules can diffuse from CO2 phase to the interface of CO2 and oil to decrease the IFT and further diffuse to oil phase to accelerate the miscibility process of CO2 and oil. The presence of polyether molecules can decrease the interaction energy, especially the vdW interactions between CO2 and oil molecules to decrease the IFT and MMP. The reduction of interaction energy is due to the dispersion force and LA-LB interactions between polyether and CO2, as well as the dispersion force interactions between polyether and oil molecules. The finding is significant to the chemical design for decreasing the IFT and MMP of CO2 and oil and further to successfully and efficiently develop shale oil by the CO2-surfactant mixed fluid.

Numerical Study on the Deposition Rate of Hematite Particle on Polypropylene Walls: Role of Surface Roughness

In this paper, we investigate the deposition of nanosized and microsized particles on rough surfaces under electrostatic repulsive conditions in an aqueous suspension. This issue arises in the general context of modeling particle deposition which, in the present work, is addressed as a two-step process: first particles are transported by the motions of the flow toward surfaces and, second, in the immediate vicinity of the walls, the forces between the incoming particles and the walls are determined using the classical DLVO theory. The interest of this approach is to take into account both hydrodynamical and physicochemical effects within a single model. Satisfactory results have been obtained in attractive conditions but some discrepancies have been revealed in the case of repulsive conditions, in line with other studies which have noted differences between predictions based on the DLVO theory and experimental measurements for similar repulsive conditions. Consequently, the aim of the present work is to focus on this particular range and, more specifically, to assess the influence of surface roughness on the DLVO potential energy. For this purpose, we introduce a new simplified model of surface roughness where spherical protruding asperities are placed randomly on a smooth plate. On the basis of this geometrical description, approximate DLVO expressions are used and numerical calculations are performed. We first highlight the existence of a critical asperity size which brings about the highest reduction of the DLVO interaction energy. Then, the influence of the surface covered by the asperities is investigated as well as retardation effects which can play a role in the reduction of the interaction energy. Finally, by considering the random distribution of the energy barrier of the DLVO potential due to the random geometrical configurations, the overall effect of surface roughness is demonstrated with one application of the complete deposition model in an industrial test case. These new numerical results show that nonzero deposition rates are now obtained even in repulsive conditions, which confirms that surface roughness is a relevant aspect to introduce in general approaches to deposition.

Effect of O2-Plasma Treatment of Mo on the Crystal Growth Mode of Pentacene of Organic Thin-Film Transistors

We report the change in the crystallinity of pentacene film on -plasma-treated molybdenum (Mo) and the electrical properties of pentacene thin-film transistors using Mo as source–drain electrodes. The surface energy of the Mo film was increased with -plasma treatment. Synchrotron radiation photoemission spectroscopy results revealed that the valence band split from the metallic Fermi level as the surface of the Mo was treated with plasma. This provides evidence that the surface of the Mo film changed to Mo oxide . Grazing-angle incidence X-ray diffraction results showed that pentacene molecules on -plasma-treated Mo has well-aligned features in the vertical direction as well as in the lateral direction, leading to a high crystalline film growth. The growth mode of pentacene changed from a tilted bulklike structure to a thin-film phase type by the treatment. This change in the growth mode is attributed to the reduction in interaction energy between pentacene and Mo via the formation of oxide at the Mo/pentacene interface. Secondary electron emission spectra showed that the work function increased by 0.55 eV after -plasma treatment on the Mo surface. Thus, the Mo oxides lowered the potential barrier for the hole injection from Mo to pentacene, increasing the drain current of bottom-contact organic thin-film transistors.