Loading...
Search for:
osmosis
0.006 seconds
Total 93 records
Improvement of performance of polyamide reverse osmosis membranes using dielectric barrier discharge plasma treatment as a novel surface modification method
, Article Polymer Engineering and Science ; Volume 59 , 2019 , Pages E468-E475 ; 00323888 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Farhadi, F ; Sharif University of Technology
John Wiley and Sons Inc
2019
Abstract
In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m-phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR),...
Improvement of performance of polyamide reverse osmosis membranes using dielectric barrier discharge plasma treatment as a novel surface modification method
, Article Polymer Engineering and Science ; Volume 59 , 2019 , Pages E468-E475 ; 00323888 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Farhadi, F ; Sharif University of Technology
John Wiley and Sons Inc
2019
Abstract
In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m-phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR),...
Techno-Economic Comparison between Reverse Osmosis and Multi-Effect Distillation for Desalination in Iran
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Feylizadeh, Mehrzad (Supervisor)
Abstract
The current work studies the economic investigation of reverse osmosis (RO) desalination unit and multi-effect distillation (MED) considering the average global and also Iran circumstances. Technical and operational parameters are taken into account for economic modeling of both methods to choose the proper and economic method for water desalination based on different operational conditions. The cost of the desalination plants is investigated in two different parts of capital cost and operating and maintenance cost. Capital cost is divided into direct and indirect cost subsections. Based on these calcifications, the effect of economic parameters on change of capital cost and operating and...
Preparation of Thin-Film Nanocomposite Membranes Based on Metal-Organic Frameworks (Mofs) and Study of their Performance in Forward Osmosis (Fo) Process
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The forward osmosis (FO) process is a high potential emerging membrane process in the seawater desalination and contaminated water treatment fields. One of the main challenges facing this process is the weak separation (high reverse solute flux, low water flux, and insufficient selectivity) and antifouling performances of its membranes. Various sections of this study focus on the development of FO membranes and their performance improvement. For this purpose, thin-film composite membranes with the same combination of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of metal-organic frameworks (MOFs) introduction on their performance. The support layer in all cases...
Thermodynamic properties of aqueous salt containing urea solutions
, Article Fluid Phase Equilibria ; Volume 325 , July , 2012 , Pages 71-79 ; 03783812 (ISSN) ; Held, C ; Samieenasab, A ; Ghotbi, C ; Abdekhodaie, M. J ; Taghikhani, V ; Sadowski, G ; Sharif University of Technology
2012
Abstract
Urea and inorganic ions are present in some of the physiological systems, e.g. urine. Understanding the interactions in urea/salt/water is a preliminary step to shed light on more complicated behavior of multi-component physiological systems. State-of-the-art models as well as thermophysical properties can be applied to understand the interactions in these systems. In order to determine such interactions densities, mean ionic activity coefficients (MIACs), osmotic coefficients, and solubility were measured in aqueous solutions of urea and different salts. Densities were determined at temperatures 293.15, 303.15, and 313.15K for urea concentrations up to 3molal and up to 1molal for NaCl....
Numerical simulation for efficient mixing of newtonian and non-Newtonian fluids in an electro-osmotic micro-mixer
, Article Chemical Engineering and Processing: Process Intensification ; Volume 107 , 2016 , Pages 11-20 ; 02552701 (ISSN) ; Mirzakhanloo, M ; Dabirzadeh, M. R ; Sharif University of Technology
Elsevier
2016
Abstract
The present study, deals with a new mixing technique using a two-phase electrode array, which is charged with alternating current (AC) signals, located in specific parts of the geometry. This significantly contributes to a chaotic mixing mechanism using a low amplitude AC voltage within a micro-channel. Study analysis demonstrates that the optimization of the effective parameters such as geometrical features, voltage amplitude, fluid inlet velocity, AC frequency and phase lag for a defined fluid can lead to an optimum and highly efficient mixer by considerably increasing disturbances in a primary highly ordered laminar flow. Three different geometries of micro mixer are studied; one-ring...
Pure axial flow of viscoelastic fluids in rectangular microchannels under combined effects of electro-osmosis and hydrodynamics
, Article Theoretical and Computational Fluid Dynamics ; 2017 , Pages 1-21 ; 09354964 (ISSN) ; Saidi, M. H ; Ebrahimi, A ; Sharif University of Technology
Abstract
This paper presents an analysis of the combined electro-osmotic and pressure-driven axial flows of viscoelastic fluids in a rectangular microchannel with arbitrary aspect ratios. The rheological behavior of the fluid is described by the complete form of Phan-Thien–Tanner (PTT) model with the Gordon–Schowalter convected derivative which covers the upper convected Maxwell, Johnson–Segalman and FENE-P models. Our numerical simulation is based on the computation of 2D Poisson–Boltzmann, Cauchy momentum and PTT constitutive equations. The solution of these governing nonlinear coupled set of equations is obtained by using the second-order central finite difference method in a non-uniform grid...
Modeling of aqueous biomolecules using a new free-volume group contribution model
, Article Industrial and Engineering Chemistry Research ; Volume 48, Issue 8 , 2009 , Pages 4109-4118 ; 08885885 (ISSN) ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
2009
Abstract
In this article, a new group contribution model is suggested for obtaining the thermodynamic properties of biomolecules in aqueous solutions. Accordingly, a Freed-FV model has been applied for the combinatorial free-volume term. The activity coefficients, solubilities, densities, and vapor pressures of amino acids and simple peptides in aqueous solutions were correlated, using the proposed group contribution model. Group interaction parameters of the proposed model were obtained by use of experimental data from amino acids available in the literature. The results demonstrate that the group contribution model can accurately correlate activity coefficient, solubility, density, and vapor...
Enhancing water desalination in graphene-based membranes via an oscillating electric field
, Article Desalination ; Volume 495 , December , 2020 ; Moosavi, A ; Nouri Borujerdi, A ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Water desalination methods on the basis of newly developed graphene-based membrane have been introduced as a more efficient alternative for the conventional water purification technologies such as classical thermal desalination and reverse osmosis (RO). However, the increase of water permeation rate and ion rejection are still the main subjects in this field. In this study, a new method based on using oscillating electric field is proposed to improve the performance of nanoporous graphene. The effects of the amplitude and oscillation frequency of the electric field and the pore size of the membrane on the water permeation and salt rejection are studied by conducting molecular dynamics...
Neural controller for a 5-link planar biped robot
, Article 16th IEEE International Conference on Robot and Human Interactive Communication, RO-MAN, Jeju, 26 August 2007 through 29 August 2007 ; 2007 , Pages 980-985 ; 1424416345 (ISBN); 9781424416349 (ISBN) ; Hamed, K ; Sharif University of Technology
2007
Abstract
The canonical problems in control of the biped robots arise from underactuation, impulsive nature of the impact with the environment and existence of the many degrees of freedom in their mechanism. Since biped walkers have fewer actuators than degrees of freedom, they are underactuated mechanical systems. In this paper according to the humans and animals locomotion algorithms, the stability of an underactuated biped walker with point feet is done by central pattern generator and feedback networks. For tuning the parameters of the CPG network, the control problem is defined as an optimization problem. This optimization problem is solved by using of Genetic algorithm. Also a new feedback...
On comparison of three multi-feed osmotic-mediation-based configurations for brine management: Techno-economic optimization and exergy analysis
, Article Desalination ; Volume 525 , 2022 ; 00119164 (ISSN) ; Ghofrani, I ; Moosavi, A ; Sharif University of Technology
Elsevier B.V
2022
Abstract
This study aims at analyzing the performance of three units known as low salt rejection reverse osmosis (LSRRO), split-feed counterflow reverse osmosis (SF-CFRO), and split-brine counterflow reverse osmosis (SB-CFRO) and implementing them in a modified multi-stage multi-feed counter-current membrane with cascade recycle for dewatering hypersaline streams to the salinity appropriate for crystallizers' feed. Exergy and primitive pinch analysis showed that dewatering is limited in SF-CFRO as the permeate inlet dictates the maximum salinity difference at the pinch point as well as high frictional pressure loss in the permeate channel. SB-CFRO and LSRRO units can reach high salinities by...
Three-dimensional simulation of urine concentrating mechanism in a functional unit of rat outer medulla. I. Model structure and base case results
, Article Mathematical Biosciences ; Vol. 258 , 2014 , pp. 44-56 ; ISSN: 00255564 ; Saidi, M. S ; Saadatmand, M ; Banazadeh, M. H ; Firoozabadi, B ; Sharif University of Technology
Abstract
The urine formation and excretion system have long been of interest for mathematicians and physiologists to elucidate the obscurities within the process happens in renal tissue. In this study, a novel three-dimensional approach is utilized for modeling the urine concentrating mechanism in rat renal outer medulla which is essentially focused on demonstrating the significance of tubule's architecture revealed in anatomic studies and physiological literature. Since nephrons and vasculatures work interdependently through a highly structured arrangement in outer medulla which is dominated by vascular bundles, a detailed functional unit is proposed based on this specific configuration....
The effect of fuel cell operational conditions on the water content distribution in the polymer electrolyte membrane
, Article Renewable Energy ; Volume 36, Issue 12 , December , 2011 , Pages 3319-3331 ; 09601481 (ISSN) ; Roshandel, R ; Sharif University of Technology
2011
Abstract
Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two-dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro-osmotic drag and convection. The effect of current density variation distribution on the water content (λ) in membrane/electrode assembly (MEA) was determined. In this work the membrane heat conductivity is considered as a...