Sorption, diffusion and vapor permeation of various penetrants through dense poly(dimethylsiloxane) membranes: a transport analysis

Favre, Éric; Schaetzel, Pierre; Nguygen, Q.T.; Clément, Robert; Néel, Jean

doi:10.1016/0376-7388(94)00060-3

Cited by 177 publications

(116 citation statements)

References 36 publications

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“…When on, tracer velocities of order v 0 = 13 µm/s are observed, corresponding to τ e = h/v e ≃ 10 3 s and v e ≃ 22 nm/s. The velocity drops below 1 µm/s when the air flow is turned off, after a response time of a few seconds, compatible with that of the water flux through the thin PDMS layer, e 2 /D PDMS ∼ 0.5 s for e ≃ 20 µm and a diffusion coefficient for water in PDMS D PDMS ∼ 10 −9 m 2 /s [9,10]. Control of the flow field translates into that of the induced concentration process.…”

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confidence: 84%

Microevaporators for Kinetic Exploration of Phase Diagrams

et al. 2006

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We use pervaporation-based microfluidic devices to concentrate species in aqueous solutions with spatial and temporal control of the process. Using experiments and modelling, we quantitatively describe the advection-diffusion behavior of the concentration field of various solutions (electrolytes, colloids, etc) and demonstrate the potential of these devices as universal tools for the kinetic exploration of the phases and textures that form upon concentration.PACS numbers: 07.90.+c, 64.75.+g Determination of the phase diagram of multicomponent systems is of importance in many realms: industrial formulation, protein cristallization, bottom up material assembly from spontaneous ordering of surfactant, polymeric or colloidal systems [1,2,3]. Depending on the application, one may want to access only the equilibrium phase diagram or gain additional information as to the metastable phases that can appear for kinetic reasons. Methods to reach these goals often imply tedious and systematic measurements, requiring for screening purposes the use of robotic platforms. Two generic strategies consist in varying (in space or time) the temperature of samples of given concentrations on the one hand, and on the other hand isothermal concentration by either removal of the solvent (osmosis, drying), external action on the solutes (sedimentation or dielectrophoresis for colloids), or studies of spontaneous interdiffusion in contact experiments.In this Letter we introduce microfluidic tools for controlled isothermal concentration of a wide range of systems, covering solutions of ions, polymers, proteins, surfactants and colloidal suspensions. Our work is inspired by recent observations [4,5] that in standard microsystems built of PolyDiMethylSiloxane (PDMS), spontaneous water permeation through the PDMS matrix induces flows that can be used to concentrate colloids. Taking a step further, we have engineered specialized microgeometries that allow us to control spatially and temporally the evaporation process as well as the resulting concentration of solutes. Their parallel implementation in microfluidic format could open the way to fast screening methods.After a brief description of the micro-devices, we demonstrate first our control of the concentration process on dilute aqueous solutions of fluorescein and nanoparticles in a simple geometry. We then discuss how microfabrication permits to widen the range of possibili- ties and applications of such devices. As a study case, we report controlled nucleation and growth of crystals of potassium chloride (KCl), and show how such experiments provide quantitative information on various thermodynamic quantities (solubility, crystal density) as well as kinetic features (sensitive to the rate of concentration).The devices -The devices used in this paper are twolayer PDMS on glass microsystems (Fig. 1) (fabrication procedure detailed in [6]). The microchannels of the bottom layer are filled with the solution of interest, while air (at controlled humidity) is circulated through the microchan...

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confidence: 84%

Microevaporators for Kinetic Exploration of Phase Diagrams

et al. 2006

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“…Sorption of solvents in polymers is non-ideal [11,12], that is, Henry's Law does not apply. The 'Hildebrand Solubility Parameter' δ is one method of estimating the affinity of a solvent for a particular polymer [13].…”

Section: Chemical Transportmentioning

confidence: 99%

Nanofiltration of organic solvents

Robinson

Tarleton

Millington

et al. 2004

Membrane Technology

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This article provides an insight into the mechanisms affecting solvent flux through dense membranes, and forms a basis for rejection studies of organic solute compounds from organic solvents. ABSTRACTTransport mechanisms and process limitations are relatively well understood for aqueous nanofiltration systems. Much work has also been done on the use of membranes for the removal of suspended matter from organic solvents. The removal of organic solute compounds from organic solvents using membrane technology has been addressed by very few workers, and little is known of the fundamental transport and separation mechanisms.The work aims to enhance the understanding of non-aqueous nanofiltration by focusing on the flux performance of organic solvents through a dense 2 μm polydimethylsiloxane composite membrane. The flux of alcohols, n-alkanes, i-alkanes and cyclic compounds were studied in deadend mode, at pressures of 10-900 kPa. Fluxes of 10-80 l/m 2 h were obtained for alkanes and cyclic compounds, whereas alcohol flux was around two orders of magnitude lower. The results suggest that the solvent flux through polydimethylsiloxane takes place via two distinct mechanisms -namely hydraulic and chemical transport. Hydraulic transport appears to dominate at pressures above 300 kPa, whereas chemical transport becomes more apparent at lower pressures.Comparison of the hydraulic transport data with a Hagen-Poisuelle model gives good agreement for similar solvents. Swelling effects caused by solvent-membrane interactions are identified as playing a major role in solvent flux behaviour, and compressibility effects are also thought to account for deviations from the Hagen-Poisuelle model. Viscous flow was verified by a nonseparation of mixtures of n-alkane and cyclic compounds, which suggests that the polydimethylsiloxane layer cannot sustain a dense structure when used in organic solvent nanofiltration applications.

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“…The literature favoured concept for nonaqueous NF systems is the solution-diffusion model first proposed by Lonsdale et al 3 , where permeation takes place by a substance dissolving in the membrane material and subsequently diffusing through it. The selectivity of the membrane is governed by differences in the solubility and diffusivity of the permeating species, with the sorption behaviour being generally non-ideal 4,5 . An alternative approach is the pore flow model, where even a dense membrane is considered to behave as if it had an appreciable free volume and pores through which viscous permeation takes place.…”

Section: Introductionmentioning

confidence: 99%