Flow and mass transfer modelling of nanofiltration

Geraldes, Vı́tor

doi:10.1016/s0376-7388(01)00458-6

Cited by 141 publications

(79 citation statements)

References 24 publications

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“…For very dilute solutions (concentrations lower than 0.2 mol/l) of a single solute, the calculation of the osmotic pressure can be made by the van't Hoff equation [14]. For higher concentrations, the osmotic pressure, π, can be given by [10,15,16]:…”

Section: Theorymentioning

confidence: 99%

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The role of adsorption on nanofiltration of azo dyes

Gomes

Gonçalves

Pinho

2005

Journal of Membrane Science

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The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (NF) of a wool textile dye solution was investigated. Solutions of C.I. Acid Orange 7 with concentrations ranging from 2 to 2000 mg/l were subjected to nanofiltration with a NF 45 membrane. An increase of flux decline with dye concentration was observed. The resistance-in-series model gives evidence that the main factor causing this flux decline is the solute adsorption. This is reinforced by the increase in the apparent rejection with dye concentration. Although osmotic pressure was taken into account, its contribution to a decrease of the driving force seems not to be significant. Adsorption resistance was calculated from a correlation between the pure water fluxes, measured before and after the essays, and feed dye concentration. A Langmuir isotherm type curve agreed well with experimental data. From the solution-diffusion model, the intrinsic rejection coefficient can be predicted as function of feed dye concentration.

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Section: Theorymentioning

confidence: 99%

“…In this work, nanofiltration experimental data are used to obtain a correlation of the osmotic pressure with the feed solute concentration [15,16]. When apparent rejection is sufficiently high, Eq.…”

Section: Theorymentioning

confidence: 99%

The role of adsorption on nanofiltration of azo dyes

Gomes

Gonçalves

Pinho

2005

Journal of Membrane Science

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“…A comprehensive review about the CFD methods applied to membrane processes has been made by Ghidossi et al (2006) [13]. Most studies were made under laminar conditions since most of the membrane processes work under these conditions [14][15][16][17]. The slit-type configuration represents the basic model to characterize the flow in industrial membrane modules, thus restricting the flow to laminar conditions and causing severe problems of CP.…”

Section: Introductionmentioning

confidence: 99%

Visualization and modeling of the polarization layer in crossflow reverse osmosis in a slit-type channel

Salcedo‐Díaz

García-Algado

Garcia‐Rodriguez

et al. 2014

Journal of Membrane Science

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The evolution of the concentration polarization layer during crossflow reverse osmosis in a slit channel has been studied. Digital Holographic Interferometry allows visualizing the polarization layer as an interference fringe pattern. An especial module with four windows has been designed to see the development of the polarization layer along the membrane channel. Several experiments with a constant transmembrane pressure of 6 bar, three different feed concentrations (3, 6 and 9 kg/m 3 ) and three different Re (13, 38 and 111) had been carried out. The process has been modelled simulating the experimental conditions. The computed results were found to be consistent with the experimental ones. All the experiments show a continuous increase of the polarization layer along the channel, regardless of the crossflow velocity, except near the outlet of the cell due to an edge effect. This increase in the polarization layer is greater at lower Re, although it does not influence very much the permeate flux. In contrast, what substantially affects the permeate flux, much more than Re number, is the feed concentration due to its osmotic pressure.

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“…The increase in axial Reynolds number (Re) induced a raise in the permeate rate as illustrated in Figure 11, due to the decreasing concentration boundary layer and an increase in wall filtration velocity [8,14]. The particles are moved by convection to the membrane surface under the transmembrane pressure effect, causing an increase in the concentration in the membrane-fluid interface.…”

Section: Resultsmentioning

confidence: 99%

“…The conditions of use of correlation (14) are such that Sc = 600 ∼ 3200, Re = 300 ∼ 1000, Re = 0.02 ∼ 0.3, and / = 0 ∼ 100. According to [6], these parameters correspond to a separation membrane system for the liquid ultrafiltration, with low particles concentration and laminar flow in the porous tube wall.…”

Section: Advances In Mechanical Engineeringmentioning

confidence: 99%

Separation Process by Porous Membranes: A Numerical Investigation

Cunha

Souza

Neto

et al. 2014

Advances in Mechanical Engineering

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A major problem associated with the membrane separation processes is the permeate flux drop, limiting the widespread of industrial application of this process. This occurs due to the accumulation of solute concentration near the membrane surface. An exact quantification of the concentration polarization as a function of process conditions is essential to estimate the system performance satisfactorily. In this sense, this work aims to predict the behavior of the concentration polarization boundary layer along the length of a permeable tubular membrane, over various operation conditions. The numerical solution of the Navier-Stokes equation, coupled to Darcy's and mass transfer equations, is obtained by the commercial software ANSYS CFX 12, considering a twodimensional computational domain. The study evaluates the effects of axial Reynolds and Schmidt numbers on the concentration polarization boundary layer thickness during the cross-flow filtration process. Numerical results have shown that the mathematical model is able to predict the formation and growth of the concentration polarization boundary layer along the length of the tubular membrane.

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Flow and mass transfer modelling of nanofiltration

Cited by 141 publications

References 24 publications

The role of adsorption on nanofiltration of azo dyes

The role of adsorption on nanofiltration of azo dyes

Visualization and modeling of the polarization layer in crossflow reverse osmosis in a slit-type channel

Separation Process by Porous Membranes: A Numerical Investigation

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