Desalination by Reverse Osmosis on Zeolite Membranes Junhang Dong and Robert Lee Petroleum Recovery Research Center (PRRC) Department of Petroleum and Chemical Engineering New Mexico Tech., Socorro, New Mexico 87801 Tina M. Nenoff Chemical and Biological Technologies, Sandia National Laboratories 1
THE MEMBRANE TECHNOLOGY GROUP Dr. J. Dong, Group leader Mr. L. Li, Ph.D student Mr. J. Monroe, MS student Dr. X. Gu, Postdoc associate Mr. A. Bourandas, MS student Mr. A. Kulkarni, MS student 2 Mr. J. Zhang, Ph.D. student
ACKNOWLEDGEMENT Financial Sponsors: DOE/NETL/NPTO (DE-FC26-00BC15326) The Sandia-University Research Program 3
Strategy for Effective Produced Water Management CBM & Oilfield Produced Water (TDS, CH ) SEPARATION Clean Water Irrigation, industrial, human consumption (Beneficial) Concentrated Prod. Water Disposal, e.g. deep well injection (costly) Challenge: Lacking of technology for efficient SEPARATION New Technology for High Concentration PW SEPARATION Maximized volume of Clean Water Minimized volume of Concentrated P.W. Effective PW Management 4
Zeolite Membranes Gas separation mechanisms: (1) Competitive adsorption-diffusion (2) Size exclusion Advantages: (1) High selectivity and flux (2) Thermal and chemical stability Desalination? Demonstrated by MD computer simulation Size exclusion of the large hydrated ions Objective of this study: Demonstrate desalination on zeolite membranes and investigate separation mechanisms MFI dp: 5.6Å 5
Contents MFI-type zeolite membrane synthesis Desalination of CBM and oilfield produced waters by reverse osmosis on MFI zeolite membranes Mechanism of water and ion transport through the zeolite membrane Conclusions/Discussions/Future Directions 6
Synthesis of Zeolite Membrane In-situ crystallization Synthesis solution 20g SiO 2 +100ml (1.0M) TPAOH+1.4g NaOH+3.2g H 2 O alpha-alumina substrate Substrate Nucleation Hydrothermal treatment Washing with DI water Crystal growth Template removal by firing at 450 C 7
Membrane Morphology and Crystal Phase Cross-section Surface Relative Intensity Zeolite Membrane α alumina substrate XRD of Zeolite on alumina support XRD of α-alumina support 0 10 20 30 40 50 2θ 8
The RO Desalination System N Regulator 2 High pressure N cylinder 2 Feed tank Pressure gauge Needle valve Ion concentration analyzed by Dionex dual-column I.C. (120) Cross-flow Cell O-ring Water bath Membrane O-ring Sample collector Evaporation controller 9
Chemical Compositions of Produced Waters Component Concentration Component Concentration Bicarbonate 790 ppm Bicarbonate 820 ppm Fluoride 222.7 ppm Chloride 106,560 ppm Chloride 9802 ppm Sulfate 3,720 ppm Sulfate 522 ppm Sodium 66,630ppm Sodium 6396 ppm Potassium 593 ppm Potassium 523 ppm Magnesium 654 ppm Magnesium 124 ppm Calcium 2511 ppm Calcium 185 ppm Bromide 93 ppm Organic (removed) Organic (removed) TDS 18,500 ppm TDS 181,600 ppm CBM produced water (Farmington, NM) Oilfield produced water (Hobbs, NM) 10
Effect of TDS on Ion rejection at 25 o C and applied pressure of 2.1 5.0 MPa Feed solution TDS (ppm) Ion Rejection Water flux kg/m 2 h NaCl solution 5.9 10 3 98% 0.126 CBM produced water (Farmington, NM) 18.5 10 3 85% 0.108 Solution of NaCl+KCl+CaCl 2 +MgCl 2 39.0 10 3 73.5% 0.084 Oilfield produced water (Hobbs, NM) 182 10 3 ~20% 0.092 Definition of ion rejection: r i = ( C i ) feed ( C ( C i ) feed i ) perm 100% 11
Salt Rejection of CBM Produced Water (TDS = 18,500 mg/l, Farmington, NM) Ion Rejection 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Na+ K+ Ca2+ Mg2+ 0 50 100 150 200 Operation time, h Ion R ejection 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% F- Cl- SO42-0 50 100 150 200 Operation Time, h Cation Anion 12
Salt Rejection of Oilfield Produced Water (TDS= 182,000 mg/l, Hobbs, NM) Cation rejection 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Na (ppm) K (ppm) Ca (ppm) Mg (ppm) 0 100 200 300 400 Operation time, h Anion rejection 100% 90% Cl- 80% SO42-70% 60% 50% 40% 30% 20% 10% 0% 0 50 100 150 200 250 300 350 400 Operation time, h Cation Anion 13
Effect of temperature on RO through MFI membrane under applied pressure of 2.75 MPa T ( o C) 0.1 M LiCl 0.1 M NaCl 0.1 M KCl 0.1 M RbCl 0.1 M CsCl R i F w R i Fw R i (%) (%) (%) (%) (%) 10 99.3 3.57 97.2 3.91 99.7 3.8 98.0 0.81 30 99.0 3.83 98.0 5.66 99.7 7.0 97.7 2.68 94.8 2.28 Fw R i Fw R i Fw 50 98.8 5.92 98.7 6.44 98.1 8.9 97.5 6.87 97.5 6.22 60 98.7 7.17 97.4 10.7 97.4 8.22 : not measured; F w : water flux with unit of mol/m 2 h. 14
Effect of Temperature on Water Transport 6 5 Ea=12.57 KJ/mol H 2 O ln(f H2 O ) 4 3 2 0.0028 0.003 0.0032 0.0034 0.0036 0.0038 1/T (1/K) K = K o e Ea RT 15
Effect of Temperature on Ion Transport -2-2 -3 Ca 2+ Ea=10.50 KJ/mol Mg2+ Ea=10.50 KJ/mol -3 ln(f Ca 2+) -4-4 ln(f 2+ ) Mg -5-5 -2-6 -3 Ea=8.81 KJ/mol Na+ K+ Ea=9.90 KJ/mol -2-6 -3 D = D e o Ea RT ln(f Na +) -4-4 ln(f K + ) -5-5 -6-6 0.0028 0.003 0.0032 0.0034 0.0028 0.0036 0.003 0.0032 0.0034 0.0036 1/T (1/K) 1/T (1/K) 16
Effect of Ion Size on the Flux Water flux, mol/m 2 h 12.0 10.0 8.0 6.0 4.0 2.0 0.020 0.016 0.012 0.008 0.004 Cation ion flux, mol/m 2 h 0.0 NaCl KCl MgCl2 CaCl2 0.000 Solution 1. Diffusion coefficient increase with increasing crystallographic ion size (Chowdhuri & Chandra, J. Chem. Phys. 2003). 2. Apparent dynamic hydration number (ADHN) (Kiriukhin and Collins. Biophys. Chem. 2002), charge density,. 17
Effect of Valence on Ion Rejection Water flux, mol/m 2 h 10.0 8.0 6.0 4.0 2.0 Water flux Ion flux 0.016 0.012 0.008 0.004 Cation flux, mol/m 2 h Water flux, mol/m 2 h 10.0 8.0 6.0 4.0 2.0 water flux ion flux 0.020 0.016 0.012 0.008 0.004 Cation flux, mol/m 2 h 0.0 0.1M NaCl 0.1M MgCl2 0.1M AlCl3 Solution 0.000 0.0 0.1M NaCl 0.1M Na2SO4 Solution 0.000 Na + Mg 2+ Al 3+ ADHN 0.30 5.85 8.68 Hydrated ion size (nm) 3 2+ + + + 0.366 Al Mg Ca Na 0.600 0.674 R + R R 2 > R > R K 18
Microstructure of The Zeolite Membrane Effective PS: 0.54 0.56nm Illustration of an intercrystal pore (Ave. Size <2 nm) Mass transport channels (1) Zeolite intracrystal pore (2) Intercrystal pores 19
2 Ion and Water Transport Through the Zeolite Membrane Ion rejection mechanism: 1. Size exclusion in the zeolitic pores ( 0.56 nm) providing very high rejection, (~100%?) 2. Overlapping double-layers relatively low rejection depending on operation conditions 20
Conclusion/Discussions/Future Directions 1. Zeolite membranes are capable for produced water treatment. 2. The ion separation mechanisms: (i) Highly selective size exclusion at zeolitic pores; (ii) Restricted ion transport in intercrystal pores by overlapping double layers does not work for high TDS. 3. Increasing temperature significantly increases water flux but does not affect ion rejection at zeolitic pores! 5. Future directions: (a) Fundamental studies to better understand the process necessary for technology development. (b) Thinner membranes for higher flux risk in more intercrystal pores. (c) Simple, efficient, and cost-effective healing methods to eliminate or minimize intercrystal pores. 21
Preliminary Results on Membrane Modification Original: R Na+ = 22%; F = 0.15 kg/m 2.h After healing: R Na+ = ~75%; F = 0.06 kg/m 2.h 22
THANK YOU! 23