Boffa, Vittorio

Christensen, Morten Lykkegaard

Farsi, Ali

English

    Aalborg UniversitetFiltration of several uncharged solutes on reverse osmosis membrane: theorymodification based on slip boundaryFarsi, Ali; Boffa, Vittorio; Christensen, Morten LykkegaardPublication date:2012Document VersionEarly version, also known as pre-printLink to publication from Aalborg UniversityCitation for published version (APA):Farsi, A., Boffa, V., & Christensen, M. L. (2012). Filtration of several uncharged solutes on reverse osmosismembrane: theory modification based on slip boundary. Poster presented at 14th Nordic Filtration Symposium,Aalborg, Denmark.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            ? You may not further distribute the material or use it for any profit-making activity or commercial gain            ? You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: December 25, 2020Filtration of several uncharged solutes on reverse osmosis membrane: Theory modification based on slip boundary         Ali Farsi*, Katja König, Vittorio Boffa, Morten Lykkegaard Christensen Department of Biotechnology, Chemistry and Environmental Engineering,  Aalborg University, 9000 Aalborg, Denmark Model procedure Introduction  Nanofiltration is a promising membrane technique with a large number of applications in treatment of process water, drinking water and wastewater.  More specifically, nanofiltration can be used to remove small organic molecules. Models for nanofiltration are usually based on non-slip condition which can be modified to slip condition as a rational  assumption.   In this paper, the effects of slip length on the rejection of uncharged solutes such as glycerol and glucose along the effective membrane thickness have been investigated. The Bowen nanofiltration transport model based on Hagen–Poiseuille equation for solvent velocity (no slip condition) has been modified by several slip conditions and a new model allowing calculation of uncharged solute rejection on the basis of a binary membrane parameter (slip length and pore radius) was developed. Input Parameters • Temperature • Trans membrane pressure • Pore size and Shape • Ionic or uncharged solute radius • Bulk feed concentration • Bulk solvent viscosity • Porosity • Tortuosity • Membrane thickness  Model Parameters calculation • Fluid Slip Length • Solvent viscosity in pore • Uncharged solute/ ion concentration within pore entrance •  Velocity • Effective pressure driving force • Uncharged solute/ ion steric partition coeffiient • Uncharged solute pore/ ion diffusion coefficient • Uncharged solute/ ion hindrance factor for convection • Solvent  permeability • Osmotic reflection coefficient. Output Result • Concentration of  solute/ ion i within pore • Concentration of solute/ ion i in concentration polarization layer • Bulk permeate concentration • Rejection • Membrane material properties • Model validation and errors • etc.  Model Input Parameter Value Description  u 1 [m h-1] solvent velocity H 1[nm] Pore height b* 0.1-0.005 [nm] Slip length Cf 10 [mol m-3] bulk feed concentration T 298.15 [K] absolute temperature η 0.001 [N s m-2] solvent viscosity within pores Z 2 [µm] Width of pore Np  10000000 The points number in pore Solute D∞ (10-9m2s-1) rs (nm) Vs (cm3mol-1) Ref Glycerol 0.95 0.26 70.8 Kiyosawa (1991) Glucose 0.69 0.365 110 Birch (1997) Results 1. Glycerol  Rej/ΔRej/ Conc. vs. Pore Length Z for various slip lengths b ((1-5): b= [0, 1e-10, 5e-11, 1e-11, 5e-12] m     Conclusion The obtained results show that by increasing the slip length which has been related to the pore size and membrane materials, the solute rejection can be increased up to approximately 5%. Concerning these results, the solute rejection can be increased by synthesis of a membrane layer with optimum conditions according to slip length. Acknowledgements The authors would like to thank Danish National Advanced Technology Foundation for project funding (Project # O59-2011-1).  *Corresponding Author: Address: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Room: D114,  Sohngaardsholmsvej 57, 9000 Aalborg, Denmark Telephone: +4599403663 , Email: alf@bio.aau.dk     2. Glucose Rej/ΔRej/ Conc. vs. Pore Length Z for various slip lengths b ((1-5): b= [0, 1e-10, 5e-11, 1e-11, 5e-12] m) Rej 1: b = 0  Rej 2: b = 0.1 nm Rej 3: b = 0.05 nm Rej 4: b = 0.01 nm Rej 5: b = 0.005 nm Comp1: b = 0  Comp2: b = 0.1 nm Comp3: b = 0.05 nm Comp4: b = 0.01 nm Comp5: b = 0.005 nm Z [m] Z [m] Z [m] Z [m] Comp1: b = 0  Comp2: b = 0.1 nm Comp3: b = 0.05 nm Comp4: b = 0.01 nm Comp5: b = 0.005 nm Z [m] Rej1: b = 0  Rej2: b = 0.1 nm Rej3: b = 0.05 nm Rej4: b = 0.01 nm Rej5: b = 0.005 nm 

Filtration of several uncharged solutes on reverse osmosis membrane: theory modification based on slip boundary

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Filtration of several uncharged solutes on reverse osmosis membrane: theory modification based on slip boundary

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