Interfacial forces, average pore size, and pore size distribution of ultrafiltration membranes

Chan, Kam; Matsuura, Takeshi; Sourirajan, S.

doi:10.1021/i300008a019

Cited by 62 publications

(42 citation statements)

References 5 publications

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“…(a) The size of the channels decreases; (b) the number of the channels increases. (2) There is a correlation between the parameters associated with the pervaporation transport of pure water and the channel diameter.…”

Section: Discussionmentioning

confidence: 99%

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements

Yamasaki

Tyagi

Fouda

et al. 1995

J of Applied Polymer Sci

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The pervaporation of pure water through homogeneous aromatic polyamide membranes was investigated. The structure of the prepared membranes was controlled by varying the solvent evaporation times before the gelation step from 5 min to 240 min. The permeation flux of pure water decreased rapidly when the solvent evaporation time increased from 5 min to 30 min, and the decrease was rather moderate at higher evaporation times. Vapor and liquid sorption measurements were used to characterize the membranes. The amount of vapor sorption at a given relative pressure increased with an increase in the solvent evaporation time. The specific surface area of the membranes, calculated from the vapor sorption isotherm, increased with evaporation time up to 30 min, and remained constant thereafter. Liquid sorption volume, on the other hand, decreased monotonically with an increase in evaporation time. The formation of channels in the membrane is used to explain the morphology change during the solvent evaporation. The increase in the solvent evaporation time gradually increases the number of the channels in the membrane and decreases their average size. Good correlation was observed between the average size of the channels (represented by the ratio of specific volume to the specific surface area) and the parameters associated with pervaporation transport. © 1995 John Wiley & Sons, Inc.

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Section: Discussionmentioning

confidence: 99%

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements

Yamasaki

Tyagi

Fouda

et al. 1995

J of Applied Polymer Sci

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“…These include adsorption of gases such as CO 2 and N 2 [4], liquid chromotography and ®ltration data correlated to pore size [5]. The results indicate that a normal or a log-normal distribution of pore sizes is a good assumption in most cases.…”

Section: Introductionmentioning

confidence: 90%

The effect of pore size distribution on the separation efficiency in surface force pore-flow model-system: isopropanol-water

Gupta

Hashim

Cui

1999

Bioprocess Engineering

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The surface force pore-¯ow (SFPF) model is based on solute-membrane material interactions at the membrane-solution interface. It has been used to model the transport of solute and solvent through membranes under the in¯uence of such forces and to determine separation ef®ciency based on the assumption of circular pores. It is evident from the model that the pore diameter has a strong bearing upon the separation ef®ciency and the mean separation ef®ciency can be determined from the pore size distribution. In this work a Monte Carlo simulation technique has been employed to generate a large number of sample pores from the mean and the standard deviation. The Gaussian distribution has been used to determine the separation ef®ciency in the SFPF model. The results have been compared with the available data for isopropanol/cellulose acetate/water system and the predicted values agree well with the published data. List of symbolsA constant characterizing electrostatic repulsive force, m B constant characterizing van der Waals attractive force, m 3 b frictional function, dimensionless C A dimensionless solute concentration at the pore outlet c A molar solute concentration, mol/m 3 D constant characterizing steric repulsion at the interface, m D w Stokes radius of water, m D AB diffusivity of solute in water, m 2 /s f solute separation based on the solute concentration in the bulk feed, dimensionless f H true value of solute separation by membrane pore, dimensionless f H areav as de®ned in Eq. (26) f H diav as de®ned in Eq. (27) k mass transfer coef®cient, m/s k H random variate R a radius of the water channel in the membrane pore, m R b membrane pore radius, m R blo pore radius, m as de®ned in Eq. (20) R bhi pore radius, m as de®ned in Eq. (21) R bmean average pore radius, m m s permeation velocity, m/sGreek letters aq dimensionless solution velocity pro®le in a cylindrical pore b 1 dimensionless solution velocity b 2 dimensionless operating pressure k f DaR b q solution density, kgam 3 , or dimensionless radial distance r standard deviation of the normal pore size distribution, m g viscosity of the solution in the pore, Pa s / potential in the interfacial force ®eld, J/mol

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“…Numerical values for the above parameters were obtained by the method described in Ref. 12 using transport equations based on the surface force-pore flow model.…”

Section: Methodsmentioning

confidence: 99%

The effect of hexane treatment on the permeation of silicone‐coated polyethersulfone membranes

Chen¹,

Miyano²,

Fouda³

et al. 1990

J of Applied Polymer Sci

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SynopsisThe polyethersulfone membranes were cast from casting solutions including poly (vinyl pyrrolidone) additive. The membranes were further dried, silicone-coated, and used for the permeation study with hydrogen and nitrogen gases. It has been found that solvent hexane which was included in the silicone rubber solution for surface coating increased the pore size on the membrane surface when poly(viny1 pyrrolidone) was present in the membrane. The above effect counteracted the pore size decrease by silicone coating, and, as a result, an H2/Nz permeability ratio of only 8.9 was achieved as compared with 28, which was obtained when the base polyethersulfone membrane was prepared from a casting solution without poly( vinyl pyrrolidone) additive. INTRODUCTIONIn contrast to most of the fundamental works on gas permeation, in which dense homogeneous membranes are used, all of commercially important membranes possess asymmetric structures. This is natural because the combination of high flux and sufficiently high separation factor for the components of gas mixtures can be achieved by the asymmetric membrane structure. It is well known that the performance of the membrane depends largely on the condition of the formation of such asymmetric structures. There is, however, only limited work in the literature in which the effect of membrane preparation variables on the membrane performance for the gas separation has been systematically studied.'-?The objective of this work is to cIarify the cause and etfect relationship between variables involved in the membrane preparation and the membrane performance. More specifically, this is one of a series of investigations which have been conducted to clarify the etfect of the pore size of the polyethersulfone base membrane and the number of the silicone coatings on t,he performance of the silicone rubber coated polyethersulfone membrane for gas separation. In our previous work,8 we have found that the maximum in the permeation rate ratio of hydrogen/ nitrogen gas system achieved by silicone-coated membranes increased with a decrease in the average pore size of the base polyethersulfone film. The natural consequence of the previous work, therefore, is to decrease the average pore size of the polyethersulfone membrane further to achieve an even higher maximum permeation rate ratio. It has to be noted that all poly-' T o whom correspondence should be addressed.,Journal of Applied Polymer Science, Vol. 41, 2169-2176 (1990) Published with permission by tJohn Wiley & Sons, Inc.Copyright owned by the Crown in right of Canada.CCC 002 1-8995/90/9-102 169-08$04.00 2170 CHEN ET AL.ethersulfone films used in the previous work were prepared from the casting solution including polyethersulfone polymer and dimethylsulfoxide solvent alone. From a separate investigation on the preparation of polyethersulfone ultrafiltration membranes, it has been known that the average pore radii of membranes prepared from casting solutions without any additives were larger than those of membranes prepared from...

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Interfacial forces, average pore size, and pore size distribution of ultrafiltration membranes

Cited by 62 publications

References 5 publications

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements

Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements

The effect of pore size distribution on the separation efficiency in surface force pore-flow model-system: isopropanol-water

The effect of hexane treatment on the permeation of silicone‐coated polyethersulfone membranes

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