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The Surfactant CTAB At Interfaces Studied By Broadband Vibrational Sum Frequency Generation

The Surfactant CTAB At Interfaces Studied By Broadband Vibrational Sum Frequency Generation. Patrick L. Hayes and Franz M. Geiger Northwestern University Department of Chemistry Evanston, IL International Symposium on Molecular Spectroscopy 62nd Meeting June 20th, 2007.

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The Surfactant CTAB At Interfaces Studied By Broadband Vibrational Sum Frequency Generation

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  1. The Surfactant CTAB At Interfaces Studied By Broadband Vibrational Sum Frequency Generation Patrick L. Hayes and Franz M. Geiger Northwestern University Department of Chemistry Evanston, IL International Symposium on Molecular Spectroscopy 62nd Meeting June 20th, 2007

  2. U.S. Crude Oil Production: Kern River Oil Field near Bakersfield, California. Taken from: Jad Mouawad, “Oil Innovations Pump New Life Into Old Wells” The New York Times, March 5th, 2007. Arctic National Wildlife Refuge Application of surfactants to oil recovery Average oil recovery rates are 20 to 40%of field’s total oil! Adapted from: Energy Information Administration http://www.eia.doe.gov/ U.S. Department of Energy http://www.fossil.energy.gov/programs/oilgas/eor/index.html (Accessed June 2007)

  3. U.S. Crude Oil Production: Crude flows through pores in well wall into fractures. Unfractured Fractured Well Bore Well Bore Sand- stone Sandstone Taken from: Armstrong, K. et al. “Advanced Fracturing Fluids Improve Well Economics” Oilfield Review, Autumn 1995. Application of surfactants to oil recovery Surfactant containing fracturing fluids can improve recovery rates to 30 to 60%. Adapted from: Energy Information Administration http://www.eia.doe.gov/ U.S. Department of Energy http://www.fossil.energy.gov/programs/oilgas/eor/index.html (Accessed June 2007)

  4. Quartz Grain Pore http://www.geos.ed.ac.uk/research/subsurface/diagenesis/quartz.html Chemical Questions Regarding Fracturing Fluids Scanning electron microscope image of oilfield sandstone: Are surfactants retained in the pores of the sandstone matrix? Under what conditions do monolayers form? Bilayers? Multilayers? (Potential experimental parameters: ionic strength, pH, [surfactant], etc.)

  5. Cetyltrimethylammonium Bromide (CTAB) + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Fused Quartz Fused Quartz Fused Quartz Fused Quartz AFM images of adsorbed CTAB layers. Taken from: Velegol et al. Langmuir2000, 16, 2548. CTAB at the fused quartz/water interface • 1) Real-time monitoring of CTAB • adsorption at the fused quartz/water • interface using Second Harmonic • Generation (SHG). 2) Characterization of adsorbed surfactant structure through sum frequency generation (SFG).

  6. SiO2 I fsec Laser time PMT Aqueous Phase Inject CTAB Teflon Reservoir SHG -- Experimental setup Hayes, P. L. et al. J. Phys. Chem.2007, ACS ASAP. Gibbs-Davis, J. M.; Hayes, P. L.; Scheidt, K. A.; Geiger, F. M. J. Am. Chem. Soc.2007,129, 7175.

  7. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Fused Quartz Fused Quartz Fused Quartz Fused Quartz More negative surface charge Less negative surface charge SHG -- The (3) technique Gouy-Chapman Model: Salafsky, J. S.; Eisenthal, K. B. J. Phys. Chem. B2000, 108, 3376. Xiao, X. D.; Vogel, V.; Shen, Y. R. Chem. Phys. Lett.1989, 163, 555. Zhao, X.; Ong, S.; Wang, H.; Eisenthal, K. B. Chem. Phys. Lett.1993, 214, 203.

  8. Adsorption Trace (pH =6.5) Adsorption Isotherm (pH=6) 400 mM NaCl 0.5 mM CTAB 400 mM NaCl 400 mM NaCl SHG -- CTAB adsorption experiments CTAB CMC Surface saturation occurs at ~1.5 mM CTAB

  9. IR: 3-10 m Delay Stage Visible: 800 nm Mono/ CCD SFG -- Experimental setup Sample Preparation: (1) Exposed glass slide to 5-mM solution of CTAB for 2-hours. (2) Removed and dried under N2 gas. Following similar procedure, adsorbed layer thickness of 1.4(2)-nm determined for silica/air interface. (From Eskilsson et al. Langmuir1998, 14, 2444.) Stokes, G. Y. et al. J. Am. Chem. Soc.2007,ACS ASAP. Voges, A. B. et al. J. Phys. Chem. B 2004,108, 18675. Voges, A. B. et al. J. Phys. Chem. C 2007,111, 1567.

  10. SSP SFG Spectra + Assignments based on literature assignments for IR and Raman spectra. 2858 cm-1: Symmetric CH2 stretching mode 2880 cm-1: Symmetric hydrocarbon CH3 stretching mode 2937 cm-1: Symmetric CH3-(N+) stretching mode 2958 cm-1: Anti-symmetric hydrocarbon CH3 stetching mode Sau, T. K.; Murphy, C. J. Langmuir2005, 21, 2923. Campbell, R. A.; Parker, S. R. W.; Day, J. P. R.; Bain, C. D. Langmuir 2004,20, 8740. Wang, W.; Gu, B.; Liang, L.; Hamilton, W. A. J. Phys. Chem. B 2004,108, 17477. Kung, K. S.; Hayes, K. F. Langmuir 1993,9, 263.

  11. SSP SFG Spectra PPP + PPP Spectrum: 2890 cm-1: Fermi resonance of the symmetric CH2 stretch 2956 cm-1: Anti-symmetric hydrocarbon CH3 stetching mode (Present in both SSP and PPP) 2967 cm-1: Combination of anti-symmetric CH3 hydrocarbon stretch and symmetric CH3-(N+) stretch. Sau, T. K.; Murphy, C. J. Langmuir2005, 21, 2923. Campbell, R. A.; Parker, S. R. W.; Day, J. P. R.; Bain, C. D. Langmuir 2004,20, 8740. Wang, W.; Gu, B.; Liang, L.; Hamilton, W. A. J. Phys. Chem. B 2004,108, 17477. Kung, K. S.; Hayes, K. F. Langmuir 1993,9, 263.

  12. + + + + + + + + 2967 cm-1 mode consistent with interdigitated CTA+ bilayer (observed previously in literature.) SFG Spectra PPP Fused Quartz 2967 cm-1: Combination of anti-symmetric hydrocarbon stretch and symmetric CH3-(N+) stretch. Sau, T. K.; Murphy, C. J. Langmuir2005, 21, 2923. Campbell, R. A.; Parker, S. R. W.; Day, J. P. R.; Bain, C. D. Langmuir 2004,20, 8740. Wang, W.; Gu, B.; Liang, L.; Hamilton, W. A. J. Phys. Chem. B 2004,108, 17477. Kung, K. S.; Hayes, K. F. Langmuir 1993,9, 263.

  13. + Water Fused Quartz Conclusions & Future Work Use deuterated CTAB to verify assignments in SFG spectra. 2) Further SFG studies of CTAB at quartz/water interface to compliment current work at quartz/air interface. In particular, probe for further evidence of interdigitated bilayer structures (or other surface structures) at these interfaces.

  14. 400 mM NaCl 0.5 mM CTAB 400 mM NaCl Well Bore Sandstone Conclusions & Future Work 3) Proof-of-concept: (3) technique can be used to track surfactant adsorption to the fused quartz/water interface, and will be used to determine conditions under which adsorption is reversible. Optimizing conditions for surfactant removal (desorption) in oil wells allows for improving recovery rates up to and beyond 60%!

  15. Funding Schlumberger Oilfield Chemical Products Northwestern University The Alfred P. Sloan Foundation Acknowledgements The Geiger Group http://www.chem.northwestern.edu/faculty

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