Charge and separation characteristics of nanofiltration membrane embracing dissociated functional groups

Abstract

The current work focused on the investigation of charge and separation characteristics of nanofiltration (NF) membrane embracing dissociated functional groups under different electrolyte solutions. The electro-kinetic method was carried out to assess the membrane volume charge density (X) with different salt concentrations ranging from 0.1 to 10 mol·m^-3 and different electrolyte species, such as type 1–1, type 2–1 and type 3–1. The Donnan steric pore model-dielectric exclusion (DSPM-DE) model was employed to evaluate the separation characteristics of the NF membrane for wide range of electrolyte concentration (from 25.7 to 598.9 mol·m^-3). The results indicated that the dissociation of the hydrophilic functional groups and the specific adsorption contributed to charge formation on membrane surface. The former played a dominant role in type 1–1 and type 2–1 electrolytes at dilute aqueous solutions (0.1–0.5 mol·m^-3). However, for type 3–1 electrolyte, specific adsorption should contribute to the charge effect to a large extent. Moreover, the correlation between the volume charge density and feed concentration was in accordance with Freundlich isotherm. Furthermore, it was found that the separation characteristic of NF membrane could be evaluated well by DSPM-DE model coupling with electro-kinetic method in a whole concentration range.

Keywords

Sulfonated polyethersulfone nanofiltration membrane / charge characteristics / electro-kinetic method / volume charge density / separation behavior

References

[1] BowenW R, MohammadA W. A theoretical basis for specifying nanofiltration membrane–dye/salt/water stream. Desalination, 1998, 117(1-3): 257-264

[2] WangM, AnQ F, WuL, MoJ X, GaoC J. Recent Developments in the measurement of zeta-potential of membrane. Chinese Journal of Analytical Chemistry, 2007, 35(4): 605-610

[3] PeetersJ M M, MulderM H V, StrathmannH. Streaming potential measurements as a characterization method for nanofiltration membranes. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999, 150(1-3): 247-259

[4] AfonsoM D, HagmeyerG, GimbelR. Streaming potential measurements to assess the variation of nanofiltration membranes surface charge with the concentration of salt solutions. Separation and Purification Technology, 2001, 22-23(1-2): 529-541

[5] ArizaM J, BenaventeJ. Streaming potential along the surface of polysulfone membranes: a comparative study between two different experimental systems and determination of electrokinetic and adsorption parameters. Journal of Membrane Science, 2001, 190(1): 119-132

[6] BandiniS. Modelling the mechanism of charge formation in NF membranes: theory and application. Journal of Membrane Science, 2005, 264(1-2): 75-86

[7] SzymczykA, FievetP, BandiniS. On the amphoteric behavior of Desal DK nanofiltration membranes at low salt concentrations. Journal of Membrane Science, 2010, 355(1-2): 60-68

[8] TakagiR, NakagakiM. Membrane potential of separation membranes as affected by ion adsorption. Journal of Membrane Science, 1992, 71(3): 189-200

[9] TakagiR, NakagakiM. Ionic dialysis through amphoteric membranes. Separation and Purification Technology, 2003, 32(1-3): 65-71

[10] SchaepJ, VandecasteeleC. Evaluating the charge of nanofiltration membranes. Journal of Membrane Science, 2001, 188(1): 129-136

[11] SchaepJ, VandecasteeleC, MohammadA W, BowenW R. Modelling the retention of ionic components for different nanofiltration membranes. Separation and Purification Technology, 2001, 22-23(1-2): 169-179

[12] FievetP, SbaïM, SzymczykA, VidonneA. Determining the ζ-potential of plane membranes from tangential streaming potential measurements: effect of the membrane body conductance. Journal of Membrane Science, 2003, 226(1-2): 227-236

[13] SbaïM, SzymczykA, FievetP, SorinA, VidonneA, Pellet-RostaingS, Favre-ReguillonA, LemaireM. Influence of the membrane pore conductance on tangential streaming potential. Langmuir, 2003, 19(21): 8867-8871

[14] YaroshchukA, RibitschV.Role of channel wall conductance in the determination of ζ-potential from electrokinetic measurements. Langmuir, 2002, 18: 2036-2038.

[15] SzymczykA, Fatin-RougeN, FievetP. Tangential streaming potential as a tool in modeling of ion transport through nanoporous membranes. Journal of Colloid and Interface Science, 2007, 309(2): 245-252

[16] VezzaniD, BandiniS. Donnan equilibrium and dielectric exclusion for characterization of nanofiltration membranes. Desalination, 2002, 149(1-3): 477-483

[17] BowenW R, MohammadA W, HilalN. Characterisation of nanofiltration membranes for predictive purposes-use of salts, uncharged solutes and atomic force microscopy. Journal of Membrane Science, 1997, 126(1): 91-105

[18] BowenW R, MukhtarH. Characterisation and prediction of separation performance of nanofiltration membranes. Journal of Membrane Science, 1996, 112(2): 263-274

[19] BowenW R, WelfootJ S. Modelling the performance of membrane nanofiltration-critical assessment and model development. Chemical Engineering Science, 2002, 57(7): 1121-1137

[20] BowenW R, WelfootJ S. Predictive modelling of nanofiltration: membrane specification and process optimization. Desalination, 2002, 147(1-3): 197-203

[21] LabbezC, FievetP, SzymczykA, VidonneA, FoissyA, PagettiJ. Retention of mineral salts by a polyamide nanofiltration membrane. Separation and Purification Technology, 2003, 30(1): 47-55

[22] SzymczykA, FievetP. Investigating transport properties of nanofiltration membranes by means of a steric, electric and dielectric exclusion model. Journal of Membrane Science, 2005, 252(1-2): 77-88

[23] GeraldesV, AlvesA M B. Computer program for simulation of mass transport in nanofiltration membranes. Journal of Membrane Science, 2008, 321(2): 172-182

[24] MohammadA W, HilalN, Al-ZoubiH, DarwishN A. Prediction of permeate fluxes and rejections of highly concentrated salts in nanofiltration membranes. Journal of Membrane Science, 2007, 289(1-2): 40-50

[25] BandiniS, VezzaniD. Nanofiltration modeling: the role of dielectric exclusion in membrane characterization. Chemical Engineering Science, 2003, 58(15): 3303-3326

[26] FregerV, ArnotT C, HowellJ A. Separation of concentrated organic/inorganic salt mixtures by nanofiltration. Journal of Membrane Science, 2000, 178(1-2): 185-193

[27] MaZ, WangM, WangD, SuB W, GaoC J. The study on interficial electrical phenomena of polyamide nanofiltration membrane through electrokinetic method. Chinese Journal of Analytical Chemistry, 2008, 36(12): 1707-1710

[28] MulderM. Basic Principles of Membrane Technology. Kluwer: Dordrecht, 1991, 149-159

[29] BouraneneS, FievetP, SzymczykA, El-Hadi SamarM, VidonneA. Influence of operating conditions on the rejection of cobalt and lead ions in aqueous solutions by a nanofiltration polyamide membrane. Journal of Membrane Science, 2008, 325(1): 150-157

[30] AfonsoM D, PinhoM N. Transport of MgSO₄, MgCl₂, and Na₂SO₄ across an amphoteric nanofiltration membrane. Journal of Membrane Science, 2000, 179(1-2): 137-154

[31] TeixeiraM R, RosaM J, NystromM. The role of membrane charge in nanofiltration performance. Journal of Membrane Science, 2005, 265(1-2): 160-166

[32] BowenW R, CaoX W. Electrokinetic effects in membrane pores and the determination of zeta-potential. Journal of Membrane Science, 1998, 140(2): 267-273

[33] AfonsoM D, PinhoM N. Mass transfer modeling for salt transport in amphoteric nanofiltration membranes. Industrial & Engineering Chemistry Research, 1998, 37(10): 4118-4127

Acknowledgements

This research was supported by the National Natural Science Foundation of China (Grant No. 20706050).

Tab.1

Nomenclature:

0-	feed/membrane interface, feed side
0+	feed/membrane interface, membrane side
δ-	membrane/permeate interface, membrane side
δ+	membrane/permeate interface, permeate side
Ak	porosity of the membrane
ci	concentration of component i in the membrane (mol·m-3)
Ci,f	concentration of component i in the retentate (mol·m-3)
d	thickness of oriented solvent layer (0.28 nm)
Di,p	pore diffusion coefficient of component i (m2·s-1)
Di,∞	bulk diffusion coefficient of component i (m2·s-1)
Ji	flux of component i (mol·m-2·s-1)
κ-1	Debye length, m
Ki,c	hindrance factor for convection
Ki,d	hindrance factor for diffusion
ri	Stokes radius of component i (m)
∆W	dimensionless excess solvation energy
x	distance normal to membrane (m)
∆x	effective membrane thickness (m)
X	effective membrane volume charge (mol·m-3)
ϵb	bulk dielectric constant, C2·J-1·m-1
ϵp	pore dielectric constant, C2·J-1·m-1
ϵM	membrane dielectric constant, C2·J-1·m-1
ϵ*	dielectric constant of oriented water layer (ϵ* = 6)
ϕi	steric partition term
σ	the electrical charge density on the membrane/electrolyte interface (C·m-2)
λi	Stokes radius of component i to pore radius ratio
ψ	electric potential in axial direction (V)
∆ψD	Donnan potential

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