Journal of Korean Society on Water Environment, Vol. 28, No. 2, pp.292-299 (2012) ISSN 1229-4144 ᆞᆞᆞ Evaluation of Forward Osmosis (FO) Membrane Performances in a Non-Pressurized Membrane System Bongchul KimChanhee BooSangyoup LeeSeungkwan Hong School of Civil, Environmental & Architectural Engineering, Korea University (Received 16 January 2012, Revised 6 February 2012, Accepted 17 February 2012) Abstract The objective of this study is to develop a novel method for evaluating forward osmosis (FO) membrane performances using a non-pressurized FO system. Basic membrane performance parameters including water (A) and solute (B) permeability coefficients and unique parameter for FO membrane such as the support layer structural parameter (S) were determined in two FO modes (i.e., active layer faces feed solution (AL-FS) and active layer faces draw solution (AL-DS)). Futhermore, these parameters were compared with those determined in a pressurized reverse osmosis (RO) system. Theoretical water flux was calculated by employing these parameters to a model that accounts for the effects of both internal and external concentration polarization. Water flux from FO experiment was compared to theoretical water fluxes for assessing the reliability of those parameters determined in three different operation modes (i.e., AL-FS FO, AL-DS FO, and RO modes). It is demonstrated that FO membrane performance parameters can be accurately measured in non-pressurized FO mode. Specifically, membrane performance parameters determined in AL-DS FO mode most accurately predict FO water flux. This implies that the evaluation of FO membrane performances should be performed in non-pressurized FO mode, which can prevent membrane compaction and/or defect and more precisely reflect FO operation conditions. keywords : Forward osmosis, Membrane performance parameter, Solute permeability, Solute resistivity for diffusion, Water permeability. (RO/NF), (MBR), (MF/UF). (, 1999;, 2002).,. To whom correspondence should be addressed. skhong21@korea.ac.kr (Cath et al., 2006).. (McGinnis and Elimelech, 2007) (Lee et al., 2010).,, (Wang et al., 2010; Yip et al., 2010). (internal concentration polarization: ICP) (Yip et al., 2010)., (thickness) (tortuosity) (porosity). 282, 2012
.. (Phillip et al., 2010; Wang et al., 2010)... (Gray et al., 2006).,.. (active layer faces feed solution: AL-FS, active layer faces draw solution: AL-DS),.,. (water permeability: A)(solute permeability: B), (solute resistivity for diffusion: K).... (concentration polarization: CP) FO (McCutcheon and Elimelech, 2006). (, ) Fig. 1. Schematic illustration of osmotic pressure profile in FO (AL-FS) mode.. AL-FS. AL-FS ( (1)). (1) (1) A,,. ( ),,. exp (2) exp (3) (solute resistivity for diffusion: K), (mass transfer coefficient: k)., (1) ( (4)). exp exp (4) Hydration Technologies Innovations (Albany, Journal of Korean Society on Water Environment, Vol. 28, No. 2, 2012
ᆞᆞᆞ OR)., mesh. 50 μm,. (Sairam et al., 2011). 7.7 cm, 2.6 cm, 0.3 cm ( 20.02 cm 2 ) cell, cell. 21.4 cm/s, 20 C. 3. RO, FO Fig. 2(a) Fig. 2(b) (Lee et al., 2010). (a) RO (A), ( (5)). (B) (250 psi) (rejection) (6) (Baker, 2004; Mulder, 1996). (5) exp (6) (5),,, (6), R, k. (b) Fig. 2. Schematic configurations of (a) RO test unit and (b) FO test unit. FO (AL-FS) (A) Fig. 3(a). Conceptual illustration of method measuring (i) water permeability and (ii) solute permeability coefficients in RO mode. Deionized (DI) water and 50 mm of NaCl solution were used as a feed solution for measurements of water and solute permeability coefficients, respectively. 282, 2012
Fig. 3(b). Conceptual illustration of method measuring (i) water permeability and (ii) solute permeability coefficients in FO (AL-FS) mode. For water permeability measurement, DI water was used as a feed solution and 0.05 and 0.10 M of NaCl solutions were used as draw solutions. For solute permeability measurement, 50 mm of NaCl solution was used as a feed solution and 3 M of dextrose solution was used as a draw solution. Fig. 3(c). Conceptual illustration of method measuring (i) water permeability and (ii) solute permeability coefficients in FO (AL-DS) mode. For water permeability measurement, DI water was used as a feed solution and 0.2, 0.4, 0.6 and 1.0 M of dextrose solutions were used as draw solutions. For solute permeability measurement, 1.0 M of NaCl solution was used as a draw solution and DI water was used as a feed solution. NaCl.,. (NaCl: 0.05, 0.10 M) OLI program (Morris Plains, NJ). (B) 50 mm NaCl, 3 M dextrose. Dextrose. NaCl (R) RO (6). FO (AL-DS) (A) dextrose. Dextrose 0.2, 0.4, 0.6, 1.0 M. ( ) OLI program (Morris Plains, NJ), ( ).. (B) 1.0 M NaCl. ( (7)). (7) Journal of Korean Society on Water Environment, Vol. 28, No. 2, 2012
ᆞᆞᆞ NaCl,,,,. (8)(B). exp (8) (solute resistivity for diffusion: K) FO (AL-FS). 0.5, 1.0, 2.0 M NaCl, (A) (B) (9).. ln (9) (,, ) Table 1. (A) (B), (K) (9).., (9). Fig. 4(a), Fig. 4(b). Fig. 4. Variation of solute resistivity for diffusion depending on the (a) water permeability and (b) solute permeability..,.,.. NaCl (0.05, 0.1, 0.5, 1.0, 2.0 M), FO (AL-FS). RO Fig. 5. Fig. 5. Table 1. Performance parameters of FO membrane determined in three different operation modes Performance parameter RO FO (AL-FS) FO (AL-DS) Water permeability (A) (μm/s atm) 0.1143 ± 0.003 0.1098 ± 0.084 0.1192 ± 0.083 Solute permeability (B) (μm/s) 0.3499 ± 0.012 0.3693 ± 0.028 0.0919 ± 0.004 Solute resistivity (K) ( 10 5 s/m) 2.1291 1.9744 2.4398 282, 2012
Fig. 5. Flux data plotted against different NaCl draw solution concentrations (0.05, 0.1, 0.5, 1.0, 2.0 M). Circles indicate experimental data, dashed line indicates model as given in Eq. 4. Model prediction is based on FO membrane parameters determined in RO mode. RO.,. RO compaction. FO RO. FO (AL-FS),,,.. (diffusion) (convection) (Phillip et al., 2010). RO Fig. 3(a),. FO (AL-FS) Fig. 1. RO. RO., (Fig. 5). FO (AL-FS) Fig. 6. RO Fig. 6. Flux data plotted against different NaCl draw solution concentrations (0.05, 0.1, 0.5, 1.0, 2.0 M). Circles indicate experimental data, dashed line indicates model as given in Eq. 4. Model prediction is based on FO membrane parameters determined in FO (AL-FS) mode.,. FO (AL-FS),.,,. RO, FO (AL-DS).. FO (AL-FS),. RO,,, (Fig. 6). Fig. 7, FO (AL-DS). dextrose. Journal of Korean Society on Water Environment, Vol. 28, No. 2, 2012
ᆞᆞᆞ... Fig. 7. Flux data plotted against different NaCl draw solution concentrations (0.05, 0.1, 0.5, 1.0, 2.0 M). Circles indicate experimental data, dashed line indicates model as given in Eq. 4. Model prediction is based on FO membrane parameters determined in FO (AL-DS) mode. FO., (Fig. 7). RO, FO (AL-FS, AL-DS),. FO (AL-FS). RO compaction,.. FO (AL-FS) RO,.,, RO. FO (AL-DS), FO. FO (AL-DS). : (m/s atm) : (m 2 ) : (m/s) : NaCl (mol/l) : NaCl (mol/l) : (mol/m 2 s) : (m/s) : (s/m) : (m/s) : (atm) : : (s) : (L) : (atm) : (atm) : (atm) : (atm) : (atm) WPM(World Premier Materials)., (1999).,, 15(1), pp. 13-22.,,, (2002).,, 18(2), pp. 159-168. Baker, R. W. (2004). Membrane Technology and Applications, 2nd ed.; J. Wiley: Chichester, New York, pp. 210-278. Cath, T. Y., Childress, A. E., and Elimelech, M. (2006). Forward Osmosis: Principles, Applications, and Recent Developments, Journal of Membrane Science, 281, pp. 70-87. Gray, G. T., McCutcheon, J. R., and Elimelech, M. (2006). Internal Concentration Polarization in Forward Osmosis: Role of Membrane Orientation, Desalination, 197, pp. 1-8. Lee, S., Boo, C., Elimelech, M., and Hong, S. (2010). Comparison of Fouling Behavior in Forward Osmosis (FO) and Reverse Osmosis (RO), Journal of Membrane Science, 365, 282, 2012
pp. 34-39. McCutcheon, J. R. and Elimelech, M. (2006). Influence of Concentrative and Dilutive Internal Concentration Polarization on Flux Behavior in Forward Osmosis, Journal of Membrane Science, 284, pp. 237-247. McGinnis, R. L. and Elimelech, M. (2007). Energy Requirements of Ammonia-Carbon Dioxide Forward Osmosis Desalination, Desalination, 207, pp. 370-382. Mulder, M. (1996). Basic Principles of Membrane Technology, 2nd ed.; Kluwer Academic: Dordrecht, Boston, pp. 191-232. Phillip, W. A., Yong, J. S., and Elimelech, M. (2010). Reverse Draw Solute Permeation in Forward Osmosis: Modeling and Experiments, Environmental Science & Technology, 44, pp. 5170-5176. Sairam, M., Sereewatthanawut, E., Li, K., Bismarck, A., and Livingston, A. G. (2011). Method for the Preparation of Cellulose Acetate Flat Sheet Composite Membranes for Forward Osmosis-Desalination Using MgSO 4 Draw Solution, Desalination, 273, pp. 299-307. Wang, R., Shi, L., Tang, C. Y., Chou, S., Qiu, C., and Fane, A. G. (2010). Characterization of Novel Forward Osmosis Hollow Fiber Membranes, Journal of Membrane Science, 355, pp. 158-167. Yip, N. Y., Tiraferri, A., Phillip, W. A., Schiffman, J. D., and Elimelech, M. (2010). High Performance Thin-Film Composite Forward Osmosis Membrane, Environmental Science & Technology, 44, pp. 3812-3818. Journal of Korean Society on Water Environment, Vol. 28, No. 2, 2012