DOCSLIB.ORG

Overview of Main Techniques Used for Membrane Characterization

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Overview of Main Techniques Used for Membrane Characterization Journal of ChemicalBartosz Technology Tylkowski, and Iren Metallurgy, Tsibranska 50, 1, 2015, 3-12 OVERVIEW OF MAIN TECHNIQUES USED FOR MEMBRANE CHARACTERIZATION Bartosz Tylkowski 1,2, Iren Tsibranska 2 1Universitat Rovira i Virgili, Received 01 October 2014 Departament de Enginyeria Química, Accepted 04 December 2014 Av. Països Catalans, 26 - 43007 Tarragona, Spain E-mail: [email protected] 2Institute of Chemical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ABSTRACT The main force of membrane technology is the fact that it works without the addition of chemicals, with relatively low energy consumption and easy and well-arranged process conductions in a compact module design. Although a good num- ber of articles and books are available on membrane separation processes, many of which are of excellent quality within their scope, most of them present research-oriented approaches of higher levels, thus making them good references in the specific field of recent membrane processes applications. This publication is focused particularly on the main techniques used for membrane characterization with supporting review of the literature and comparative discussion. Keywords: porous membrane characterization, active pore size, pore size distribution, charaterization techniques. INTRODUCTION mainly give information on membrane morphology and structure, chemical and physical properties. The dynamic Membrane technologies have been established as techniques are of fundamental importance when inves- an effective and commercially attractive option for tigating membrane performance. Some characterisation separation and purification processes in the chemical techniques are destructive for the membrane, while the and its allied industries dealing with fuel cell [1, 2], non-destructive ones are applied also to monitor the gas separation [3], food chemistry [4], pharmaceutical membrane performance during its use. Except for bub- industry and medicine [5, 6], water treatment [7], con- ble pressure all other reported techniques have not yet centration/separation of extracts [8 - 10] , etc. No doubts, been standardized or harmonized. This fact often causes the membranes are now competitive for conventional confusion and can be misleading. Publications, aimed techniques, with a wide variety of applications, both to classify and comparatively discuss the advances in industrial and scientific. membrane characterization techniques have appeared The aim of this article is to provide a comprehen- recently [11]. Table 1 shows the main characterization sive yet concise overview of main techniques used for tests. membrane characterization. Bubble pressure Characterisation techniques can be classified into This method was initiated by Bechhold in 1908 [12] static and dynamic techniques. The static techniques and is based on the fact that the pressure (P) necessary to 3 Journal of Chemical Technology and Metallurgy, 50, 1, 2015 Table 1. Main characterization test. Method Characteristic Typology M P dynamic Bubble pressure Maximum pore size non x x destructive dynamic Gas and liquid displacement Pore size distribution non x x methods (GLDP-LLDP destructive statistic Mercury porosimetry (MP) Pore size distribution x destructive Top layer thickness Scanning Electron Microscopy Surface porosity (SEM), statistic Pore size distribution x Transmission Electron destructive Qualitative structure Microscopy (TEM) analysis static Atomic force microscopy Surface porosity non (AFM) destructive dynamic Flux and retention Permeability, non x measurements Selectivity, MWCO destructive static Gas adsorption/desorption Pore size distribution non x (GAD) destructive dynamic Permporometry Pore size distribution non x x destructive SEM + X-Ray microanalysis Chemical analysis static (EDS) Surface studies destructive X-Ray photoelectron Chemical analysis static spectroscopy Surface studies destructive Functional group Infrared Spectroscopy (FT-IR, static analysis ATR, Photoacustic) destructive Surface studies non Contact angle measurement Surface studies destructive Stress-Strain measurements distructive blow a gas through a liquid-filled capillary is inversely wetting (the contact angle is equal zero) the pore size proportional to the capillary radius (r). The pore size can has to be calculated from the equation (2): be calculated using the Cantor equation (1): 1.44 r(µm) = (2) 2⋅g P(bar) P = ⋅ cos θ (1) r The main advantages of this test are: where q is a contact angle and g is a surface tension. ● non-destructive method, The bubble point test is a measure of the radius of ● very simple procedure and apparatus, the largest pore, since, according to Cantor equation, ● very useful for integrity test. the gas will pass through it first. For air-water system Unfortunately the test does not give information where the surface tension (g) is 72 mN/m and complete on the membrane pore size distribution and because of 4 Bartosz Tylkowski, Iren Tsibranska the very high air-water surface tension high pressure closed or bottle ended ones, (which can cause membrane compression) is needed for ● it does not use too high pressures, thus avoiding gas permeation through small pores (in fact the lower mechanical over-stress of the membrane during the limit of the measurable pore diameter is about 13 nm) test that could result in membrane damage or structure [13]. For instance, the bubble points method was used collapse; for three hollow fiber polyphenylsulfone membranes ● it operates quickly which makes analysis simple in iso-propanol to determine the maximum pore size and easily manageable. [13], ranging from 53 to 237 nm at pressures between A pair of immiscible liquids with low interfacial 9 and 2 bar. Close to the lower limit of detection of the tension are used which means that pore sizes can be method are the results with semi-crystalline poly(ether measured at relatively low pressures. The procedure ether ketone) hollow fiber membrane in water, where consists in filling the membrane with the wetting liquid, the largest pore was about 15 nm at applied pressure and then displacing it with the other one. By monitoring 4792 kPa [14]. the pressure and the flow through the membrane, the corresponding pore radius opened at a given applied Liquid-liquid displacement porosimetry pressure can be calculated using the Cantor equation, The liquid-liquid porosimetry (LLDP) is a method provided that contact angle between the liquid-liquid that can be used to provide information on the pore interface and the membrane material can be assumed size distribution of membranes with small pores. The to be zero: procedure is based on the same principles of the air- 2g liquid displacement or extended bubble point technique, ∆p = (4) both methods using the correlation between the applied r pressure and the pore radius rp open to flux as given by By increasing the applied trans-membrane pressure Washburn [15]: stepwise, corresponding pore radius and flow values, 2g cosθ represented as the permeability of the membrane, are ∆p = (3) obtained. Thus a pore size distribution of permeability rp contributions can be evaluated. Assuming cylindrical g being the surface tension and q the contact angle pores, the Hagen-Poiseuille equation can be used to between the permeating interface and the pore material. correlate the volume flow, VJ , and the number of pores The high potentiality of this technique in order to per surface unit, N, having a given pore radius, r. For evaluate the active pores in the nano- and subnanometer each pressure step, Δpi, the corresponding volume flow range (usually dp > 1 nm) makes it a very promising measured is correlated with the number of pores thus technique to study the pore size distribution of ultra- opened by [6]: filtration (UF) and nanofiltration (NF) membranes i Nrpπ 4∆ = kk i because of the relatively low applied pressures which JVi ∑ (5) k =1 8ηδ do not cause membrane compaction. Results with polymer membranes with pore sizes from 0.4 μm to 8 where η is the dynamic viscosity of the displacing th nm have proved the usefulness of the LLDP method for fluid, Nk is the number of pores in the class k per optimizing membrane making conditions and accurate unit membrane surface and δ is the pore length. This estimation of performance related capabilities [16]. The could be used to estimate size distributions in num- advantages of LLDP can be viewed in several directions: ber of pores. It should be remembered that Hagen- ● it tests the membrane in the wet state, so can give Poiseuille´s law in that simple form only holds for information very close to the normal operating condi- flow through cylindrically shaped straight pores. Thus, tions of the membrane, the so obtained pore size distributions should be more ● it also evaluates only the open pores, not any model-dependent. 5 Journal of Chemical Technology and Metallurgy, 50, 1, 2015 Liquid and air permeability found application in structures like glassy polymers Permeability of a membrane for a certain liquid (examples are known in the study of PIOFG polymers can be considered as a characteristic parameter; often [20], characterization of the support membrane in case the so-called hydraulic radius is calculated from the of thin film composite OSN membranes [21],as well as measured fluxes. In such an analysis, the permeability in the characterization of micro- and mesopore materials is determined, the porosity E, the tortuosity z and the as composite amorphous (ex. TiO2–ZrO2–organic) [23] membrane thickness 1 are estimated (or preferably deter- or semi-crystalline polymer (ex. poly(ether ether ketone) mined) and subsequently the pore size can be calculated PEEK [22] membranes. from the Hagen-Poiseuille equation (5). Permporometry (pore size distribution) It is obvious that such an approach depends largely This technique was initiated by Eyraud and modified on the model as well as on the estimated values used. by Katz et al. [24, 25]. The method is based on the fact Also, the model cannot discriminate between a system that the vapour pressure at the surface of a liquid depends with few large pores and one with a large number of on its curvature. The vapour is capillary-condensed in small pores.
Load more

Recommended publications
  • Capillary Condensation in Confined Media
    Capillary Condensation in Confined Media Elisabeth Charlaix1 and Matteo Ciccotti2,∗ Handbook of Nanophysics - Volume 1 Edited by Klaus Sattler CRC Press (To appear in June 2010) 1Laboratoire de Physique de la Mati`ere Condens´ee et Nanostructures, UMR5586, CNRS, Universit´eClaude Bernard Lyon 1, Domaine Scientifique de la Doua, Bˆatiment L´eon Bril- louin, 43 Boulevard du 11 novembre 1918, 69622, Villeurbanne, France 2Laboratoire des Collo¨ıdes, Verres et Nanomat´eriaux, UMR 5587, CNRS, Universit´e Montpellier 2, Place Bataillon, cc26, 34095, Montpellier, France Keywords : capillary condensation, confined fluids, wetting, SFA, AFM ∗ e-mail: [email protected] phone: +33-(0)4-67143529 Abstract We review here the physics of capillary condensation of liquids in confined media, with a special regard to the application in nanotechnologies. The thermodynamics of capillary condensation and thin film adsorption are first exposed along with all the relevant notions. The focus is then shifted to the modelling of capillary forces, to their measurements techniques (including SFA, AFM and crack tips) and to their influence on AFM imaging techniques as well as on the static and dynamic friction properties of solids (including granular heaps and sliding nanocontacts). A great attention is spent in investigating the delicate role of the surface roughness and all the difficulties involved in the reduction of the probe size to nanometric dimensions. Another major consequence of capillary condensation in nanosystems is the activation of several chemical and corrosive processes that can significantly alter the surface properties, such as dissolution/redeposition of solid materials and stress-corrosion arXiv:0910.4626v1 [physics.flu-dyn] 24 Oct 2009 crack propagation.
    [Show full text]
  • Surface Area and Pore Size Determination 19/10/2007 A
    Modern Methods in Heterogeneous Catalysis Research Surface area and pore size determination 19/10/2007 A. Trunschke Further reading S. Lowell, J.E. Shields, M.A. Thomas, M. Thommes, Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density, Kluwer Academic Publisher, Dordrecht, 2004. R. Brdička, Grundlagen der physikalischen Chemie, Deutscher Verlag der Wissenschaften, Berlin 1982. F. Schüth, K.S.W. Sing, J. Weitkamp (Eds.), Handbook of Porous Solids, Vol. 1, Wiley-VCH, Weinheim 2002. G. Ertl, H. Knözinger, J. Weitkamp (Eds.), Handbook of Heterogeneous Catalysis, VCH, Weinheim, 1997. Outline 1. Introduction 2. Adsorption 3. Surface area measurements 4. Adsorption in micropores 5. Capillary condensation in mesopores 6. Experimental Modern Methods in Heterogeneous Catalysis Research; 19/10/2007; Surface Area and Pore Size Determination; A. Trunschke 2 Heterogeneous catalysis 1 600-800°C (NH4)2[PtCl6] → Pt with high surface area 2 H2 + O2 → 2 H2O Johann Wolfgang Döbereiner‘s lighter (1823) adsorbent surface area [m2/g] Some catalysts and support charcoal 300 - 2500 materials in heterogeneous silica gel 300 -350 catalysis γ-alumina 200 - 500 zeolites 500 - 1100 Modern Methods in Heterogeneous Catalysis Research; 19/10/2007; Surface Area and Pore Size Determination; A. Trunschke 3 Factors affecting surface area 1 1 particle of edge 1018 particles of edge lenght = 1 m lenght = 10-6 m size 2 -12 2 S=6 m Si=6x10 m 6 2 Stotal=6x10 m shape MoVTeNbOx porosity Aerosil 300 S = 300 m2/g www.aerosil com Structure of ZSM-5 Modern Methods in Heterogeneous Catalysis Research; 19/10/2007; Surface Area and Pore Size Determination; A.
    [Show full text]
  • Theoretical Models for Surface Forces and Adhesion and Their Measurement Using Atomic Force Microscopy
    Int. J. Mol. Sci. 2012, 13, 12773-12856; doi:10.3390/ijms131012773 OPEN ACCESS International Journal of Molecular Sciences ISSN 1422-0067 www.mdpi.com/journal/ijms Review Theoretical Models for Surface Forces and Adhesion and Their Measurement Using Atomic Force Microscopy Fabio L. Leite 1,*, Carolina C. Bueno 1, Alessandra L. Da Róz 1, Ervino C. Ziemath 2 and Osvaldo N. Oliveira Jr. 3 1 Nanoneurobiophysics Research Group, Department of Physics, Chemistry and Mathematics, Federal University of São Carlos (UFSCar), P.O. Box 3031, CEP 18052-780, Sorocaba, São Paulo, Brazil; E-Mails:[email protected] (C.C.B.); [email protected] (A.L.D.R.) 2 Institute of Geosciences and Exact Sciences, São Paulo State University (UNESP), P.O. Box 178, CEP 13550-970, Rio Claro, São Paulo, Brazil; E-Mail: [email protected] 3 Institute of Physics of São Carlos, University of São Paulo (USP), P.O. Box 369, CEP 13560-970, São Carlos, São Paulo, Brazil; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +55-015-3229-6014; Fax: +55-015-3229-5902. Received: 2 July 2012; in revised form: 7 September 2012 / Accepted: 17 September 2012 / Published: 8 October 2012 Abstract: The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS), it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion.
    [Show full text]
  • Studies of Nano-Structured Liquids in Confined Geometries and At
    CORE Metadata, citation and similar papers at core.ac.uk Provided by Kent Academic Repository Studies of nano-structured liquids in confined geometries and at surfaces. J. Beau W. Webber∗,a,b aInstitute of Petroleum Engineering, Heriot-Watt University, Edinburgh. EH14 4AS bSchool of Physical Sciences, University of Kent, Canterbury, Kent. CT2 7NH Key words: liquids, water, ice, confined geometry, pores, NMR relaxation, neutron scattering, cryoporometry PACS: 64.60.-i, 65.60.+a, 81.07.-b, 03.75.Hh, 05.70.Fh, 64.60.Qb, 64.70.Dv, 68.03.Cd, 68.08.-p, 82.56.Na, 82.56.Ub, 61.43.Fs, 61.43.Gt, 61.46.+w, 82.60.Qr Contents 1 Introduction. 3 1.1 Samples............................... 5 1.2 Methods............................... 6 2 The thermodynamics of liquids in nano-pores. 6 2.1 The geometry term in the Gibbs-Thomson equation. 9 2.2 Second order (linearity) terms in the Gibbs-Thomson equation. 10 ∗Correspondence address: Beau Webber, Lab-Tools Ltd., Canterbury Enterprise Hub, University of Kent, Canterbury, Kent. CT2 7NJ. +44 (0) 1227 82 4675 Email address: [email protected] (J. Beau W. Webber) URL: http://www.Lab-Tools.com (J. Beau W. Webber) Preprint submitted to Progress in Nuclear Magnetic Resonance SpectroscopyAugust 23, 2009 3 The application of NMR relaxation, diffusion and cryoporom- etry techniques to the study of the properties of liquids in pores. 11 4 NMR Cryoporometry : experimental. 13 4.1 NMR Cryoporometry : experimental calibration of kGT for the meltingtransition. 16 4.2 NMR Cryoporometry : experimental effect of measuring time on the measured melting transition.
    [Show full text]
  • 2 Liquid Surfaces 2.1 Microscopic Picture of the Liquid Surface
    2 Liquid surfaces 2.1 Microscopic picture of the liquid surface A surface is not an infinitesimal sharp boundary in the direction of its normal, but it has a certain thickness. For example, if we consider the density p normal to the'surface (Fig. 2.1), we can observe that, within a few molecules, the density decreases from that of the bulk liquid to that of its vapor [11]. k (a) (b) Interfacial bulk density region , - - , A IN, k Liquid 1 V f Gas phase \ phase >^ 0.4- 0.2- 1.0 1.5 2.0 3.0 Distance Distance (nm) Figure 2.1: Density of a liquid versus the coordinate normal to its surface: (a) is a schematic plot; (b) results from molecular dynamics simulations of a n-tridecane (Ci3H28) at 27°C adapted from Ref. [12]. Tridecane is practically not volatile. For this reason the density in the vapor phase is negligible. The density is only one criterion to define the thickness of an interface. Another possible parameter is the orientation of the molecules. For example, water molecules at the surface prefer to be oriented with their negative sides "out" towards the vapor phase. This orientation fades with increasing distance from the surface. At a distance of 1-2 nm the molecules are again randomly oriented. Which thickness do we have to use? This depends on the relevant parameter. If we are for instance, interested in the density of a water surface, a realistic thickness is in the order of 1 nm. Let us assume that a salt is dissolved in the water.
    [Show full text]
  • Porométrie Liquide-Liquide, Évaporométrie Et Simulations Sur Réseau De Pores
    En vue de l'obtention du DOCTORAT DE L'UNIVERSITÉ DE TOULOUSE Délivré par : Institut National Polytechnique de Toulouse (Toulouse INP) Discipline ou spécialité : Dynamique des fluides Présentée et soutenue par : M. OTMAN MAALAL le mercredi 7 octobre 2020 Titre : Porométrie liquide-liquide, évaporométrie et simulations sur réseau de pores. Ecole doctorale : Mécanique, Energétique, Génie civil, Procédés (MEGeP) Unité de recherche : Institut de Mécanique des Fluides de Toulouse ( IMFT) Directeur(s) de Thèse : M. MARC PRAT M. DIDIER LASSEUX Rapporteurs : M. DENIS BOUYER, UNIVERSITE MONTPELLIER 2 M. PASCAL ROYER, Laboratoire de Mécanique et Génie Civil Membre(s) du jury : Mme CORINNE CABASSUD, INSA TOULOUSE, Président M. ANTHONY SZYMCZYK, UNIVERSITE RENNES 1, Membre M. DIDIER LASSEUX, CNRS AQUITAINE, Membre M. MARC PRAT, CNRS TOULOUSE, Membre Remerciements Je tiens à remercier chaleureusement toutes les personnes qui ont contribué de prés ou de loin à l’élaboration et la réussite de ce travail de thèse. Je remercie d’emblée mes directeurs de thèse Marc Prat et Didier Lasseux pour leurs conseils ainsi que leur grande disponibilité qui a permis à ce travail de se dérouleur dans les meilleures conditions. Ce travail n’aurait pas pu aboutir sans le soutien de l’Institut de la Filtration et des Techniques Séparatives (IFTS) qui s’est amplement investi dans ce projet. Dans ce sens, je tiens à remercier M. Vincent Edery, directeur général de l’IFTS, pour sa confiance et son engagement dans ce projet. Je remercie également René Peinador, ingénieur de recherche à l’IFTS, pour son encadrement et son implication dans l’aspect expérimental de la thèse.
    [Show full text]