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Vatanpour V.,Petrochemical Research and Technology Company | Vatanpour V.,Kharazmi University | Esmaeili M.,Petrochemical Research and Technology Company | Esmaeili M.,Research Institute of Petroleum Industry RIPI | Farahani M.H.D.A.,Petrochemical Research and Technology Company
Journal of Membrane Science | Year: 2014

Flat sheet asymmetric amine-functionalized multiwalled carbon nanotubes (NH2-MWCNTs)/polyethersulfone (PES) nanocomposite nanofiltration membranes with different nanofiller contents were prepared by the phase inversion method. The characteristics of the mixed matrix membranes were analyzed by SEM, AFM, contact angle and zeta potential measurements. The performance of the membranes was evaluated in terms of pure water flux (PWF), static protein adsorption and bovine serum albumin (BSA) filtration. Results showed that the hydrophilicity and PWF of the nanocomposite membranes were enhanced with increase of NH2-MWCNTs dosages. Increasing the nanotube dosages from 0wt% to 0.045wt% led to increase of PWF from 13.6 to 23.7L/m2h. The SEM images illustrated that the fabricated membranes possessed a typical asymmetric finger-like structure. The salt rejection experiments and zeta potential measurements evidenced that the surface charge of the NH2-MWCNT embedded membranes was negative and the retention mechanism of the solutes was mainly the Donnan exclusion mechanism. The salt retention sequence for 0.045wt% NH2-MWCNT was Na2SO4 (65%)>MgSO4 (45%)>NaCl (20%) after 180min filtration. The increase of the salt solution pH caused more negative surface charge and higher retention. The addition of the modified MWCNTs, in BSA filtration analysis, led to significant improvement of the fouling recovery ratio (FRR) due to lower roughness, more negatively charged surface and higher hydrophilicity of the membrane surface. © 2014 Elsevier B.V. Source

Khorasani M.M.,Amirkabir University of Technology | Khorasani M.M.,Petrochemical Research and Technology Company | Ghaffarian S.R.,Amirkabir University of Technology | Goldansaz S.H.,Amirkabir University of Technology | And 2 more authors.
Composites Science and Technology | Year: 2010

This novel research aims to develop, for the first time, microcellular polyethylene fiber-reinforced polyethylene (PE/PE) clay containing nano-composites during a solid-state microcellular foaming process using supercritical nitrogen (scN2) as a foaming agent. Results show that by employing clay nanoparticles in the matrix, expansion ratio of the microcellular processed composites enhance, because of the nucleating effect of nanoparticles. Microcellular nano-homocomposite has an average cell size of 0.5μm. Trans-crystalline layer of composites with a length of about 3μm; remain intact during the foaming process but the bulk matrix crystalline structure alters to a more oriented " quasi-fibrillar" structure after foaming. Microcell growth in the amorphous interlamellar regions exerts a tension on the neighboring lamellas which cause some orientation on them. The DSC studies show the emerging of new crystalline sectors with a lower melting point which affirms the creation of a less perfect crystalline morphology due to cell wall movements during cell growth step and subsequent stabilization period of the cells. © 2010 Elsevier Ltd. Source

Esmaeili M.,Razi University | Madaeni S.S.,Razi University | Barzin J.,Iran Polymer And Petrochemical Institute | Yousefimehr N.,Petrochemical Research and Technology Company
Separation and Purification Technology | Year: 2011

Structural and permeation properties of PES/PVP electrolyte composite membranes including association and dissociation behavior of silver nitrate salt within the polymer structure, structural situation of electron donor groups of membranes, surface and structural charge of membranes, crystalline variation of membrane active layer before and after salt addition and permeation properties of these membranes at different pressures including low pressures were evaluated. Structural evaluation through FTIR analysis revealed that the distributional condition of carrier agents is affected by increasing the AgNO 3 concentration. The efficiency of carriers for ethylene transportation is decreased by salt addition at molar concentrations more than 25%. However, according to the results obtained from zeta potential experiment, increasing the salt concentration enhances the surface and structure charge of membranes. Due to the salt crystals formation, the ascending trend of active layer crystallinity stopped at a salt molar concentration more than 25%. These physical and chemical reactions in the active layer structure caused the ethylene selectivity of final membranes to decrease at a salt molar concentration being more than 25%. The separation efficiency of a membrane with the AgNO 3 concentration of 25% was the most efficient situation. Adding a very thin and flexible PDMS layer on the surface of PES/PVP membrane in order to increase the real and ideal ethylene selectivity in the separation process was effective. Moreover, blending AgBF 4 and AgNO 3 salts was a new method for selectivity increament, which was applied in this research. © 2011 Elsevier B.V. All rights reserved. Source

Dehnavi M.A.,Iran University of Science and Technology | Shahhosseini S.,Iran University of Science and Technology | Hashemabadi S.H.,Iran University of Science and Technology | Ghafelebashi S.M.,Petrochemical Research and Technology Company
International Communications in Heat and Mass Transfer | Year: 2010

The hydrodynamics and temperature of a two-dimensional gas-solid fluidized bed of gas phase olefin polymerization reactor had been studied. A two-fluid Eularian Computational Fluid Dynamics (CFD) model with closure relationships according to the kinetic theory of granular flow has been applied in order to simulate the gas-solid flow. Fluidization regime and gas-solid flow pattern were investigated using three different drag models. Model predictions of bed pressure drop were compared with corresponding experimental data reported in the literature to validate the model. The predicted values were in reasonable agreement with the experimental data. The temperature behavior of fluidized bed with various drag models was investigated. The temperature gradient in the primary section of the bed was much larger than the gradient in other sections and the effect of all drag models on temperature gradient along the bed was approximately similar. © 2010 Elsevier Ltd. All rights reserved. Source

Torabi S.R.,Islamic Azad University at Tehran | Torabi S.R.,University of Yazd | Fazeli N.,Islamic Azad University at Tehran | Zarand M.G.,Petrochemical Research and Technology Company
Journal of Applied Polymer Science | Year: 2012

In this research work, effect of dimethyl formamide (DMF) as an external electron donor in gas phase ethylene/1-butene copolymerization process in the presence of Ziegler-Natta catalyst has been investigated. Different experiments were performed using TiCl4/MgCl2 as catalyst, triethyl aluminum as cocatalyst and in the presence of various amounts of DMF as an external electron donor. Then, effect of DMF on various parameters such as catalyst activity, molecular weight, and short chain branching content of the samples has been studied. The results showed that the more the ratio of DMF/Ti, the lower the catalyst activity. Moreover, the curves relating molecular weight and short chain branching content of the samples to the ratio of DMF/Ti passed through an extremum point at about DMF/Ti = 0.25. A justification for the occurrence of the extremum point has been proposed in this research work, and some analysis methods are adopted to confirm the suggested justification. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1267-1272, 2012 Copyright © 2011 Wiley Periodicals, Inc. Source

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