توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Development of a mass transport model for predicting pervaporative performance of benzene \cyclohexane mixture through Polyurethane membranes
نویسنده(ها): ، ،
اطلاعات انتشار: دوازدهمین کنفرانس دینامیک شاره ها، سال
تعداد صفحات: ۱۱
Separation of organic mixtures by membrane based Pervaporation process using dense polymeric membranes is usually analyzed in terms of the solution–diffusion model which assumes that a permeating component is first dissolved in the membrane and then diffuses through the membrane due to its driving force. Therefore the separate evaluation of sorption and diffusion phenomena is necessary to determine the controlling step in overall mass transport in the membrane. In this article, the pervaporative separation of benzene from its mixture with cyclohexane by polyurethane membranes was studied over the entire concentration range 0–100% benzene at 25 C o through a rigorous modeling. The validity of the proposed model was examined by the experimental data available in the literature. The sorption of components into the polyurethane was modeled using classical Flory–Huggins thermodynamic model. The binary (polymer–component and component–component) interaction parameters were calculated using pure component uptake data. Using these parameters, the multicomponent sorption performance was then predicted by the extended Flory–Huggins model. Diffusion step was modeled by Maxwell–Stefan formulation using concentration dependent diffusion coefficients. The results reveal a close agreement between the experimental data and the predicted sorption and permeation values. The results also
indicated the aromatic compounds are preferentially sorbed into polyurethane over the entire rage of composition.

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۲Dielectrophoretic technique for separation of o\w nanoemulsion
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۹
Dielectrophoresis (DEP) is an efficient electro–kinetic technique with great potential for demulsification. We present an experimental study to the dynamic behavior of particles under DEP using AC–electric field. DEP is produced by polarization effects when particles are exposed to non uniform electric field. DEP is applied to remove of sunflower oil–particles in nanometer scale which have dispersed to the water [oil in water emulsion (o\w)]. In a DEP field the polarized particles experience a force that can cause them to move to regions of high or low electric field,depending on the particle polarizability (electrical conductivity) compared with the suspendingmedium. According to the low conductivity (using electrical conductivity measurement) ofdispersed phase (oil conductivity) in comparison to water as continuous phase, DEP–force will tend to move the particles towards the weakest or minimum region of the electric field (dd −dc = – 0.095), the negative number means, it is about a negative–dielectrophoretic process (n–DEP). The oil–particle size is shown using AFM (Atomic force microscope) between 25 nm to 250 nm. The largest part of particles is between 50 nm to 60 nm.<\div>
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