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The Impact of Surface Heterogeneity on Particle Deposition

The Impact of Surface Heterogeneity on Particle Deposition. Melissa Sy Department of Chemical Engineering California State Polytechnic University, Pomona Presentation for Bioengineering Research In Technical Excellence (BRITE program) 2008. Outline. Background Research Objective

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The Impact of Surface Heterogeneity on Particle Deposition

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  1. The Impact of Surface Heterogeneity on Particle Deposition Melissa Sy Department of Chemical Engineering California State Polytechnic University, Pomona Presentation for Bioengineering Research In Technical Excellence (BRITE program) 2008

  2. Outline • Background • Research Objective • Experimental Approach • Results & Discussion • Conclusion

  3. Background Biofouling is a problem… • An undesired attachment and accumulation of organisms on surfaces in an aqueous environment • Universal problem • High costs

  4. Target Biofilm Developmental Process

  5. Governing forces: DLVO type: Van der Waals attraction Electrostatic interaction Specific interactions: Electrosteric interaction and hydrophobic interaction, etc. Microorganism Adhesion = Functionof solution chemistry, microorganism heterogeneity, substratum heterogeneity, growth phase, hydrodynamic condition, etc. Why Colloids?

  6. Objectives How does surface roughness influence the attachment behavior (physical heterogeneity)? What effects do zeolite coatings have on deposition (chemical heterogeneity)?

  7. Experimental Setup

  8. Quantifying Colloid Deposition Total flow rate = 2 Co = 2x107 * microscope viewing area (204.7 mm × 152.6 mm)

  9. Results & Discussion

  10. Mirror finish 600-grit polished unpolished Stainless Steel Comparison

  11. unpolished 600-grit polished 1200-grit polished Aluminum Alloy Comparison

  12. SEM of ZSM-5 coated Al & SS top side side Aluminum Alloy Stainless Steel

  13. Zeta Potential (mV) 1 mM 10 mM 100 mM Aluminum 4.39 ± 0.16 43.21 ± 1.99 * Stainless Steel 4.40 ± 0.69 45.40 ± 1.45 * ZSM-5 coating -12.57 ± 0.25 25.38 ± 5.54 * CML colloids -85.66 ± 0.49 -91.99 ±2.65 -54.10 ± 1.54 * Not available due to the Electro Kinetic Analyzer limitation

  14. Colloid Deposition Results in KNO3

  15. Zeta Potential (mV) 1 mM 10 mM 100 mM Aluminum 4.39 ± 0.16 43.21 ± 1.99 * Stainless Steel 4.40 ± 0.69 45.40 ± 1.45 * ZSM-5 coating -12.57 ± 0.25 25.38 ± 5.54 * CML colloids -85.66 ± 0.49 -91.99 ±2.65 -54.10 ± 1.54 * Not available due to the Electro Kinetic Analyzer limitation

  16. Colloid Deposition Results in KNO3

  17. Conclusions Surface roughness is a controlling factor on particle deposition at low ionic strength in which system entails a weak electric double layer. The electric double layer dominates the deposition rate at higher ionic strengths and similar surface charges. ZSM-5 coatings decrease deposition rate when compared to bare metal surface counterparts at low ionic strength.

  18. Acknowledgements • Dr Sharon Walker • Gexin Chen • Jun Wang • National Science Foundation • UCR Bacterial Adhesion Research Laboratory members (Amy, James) • Rajwant S. Bedi • Thanks to Dr. Yushan Yan for provision of zeolite coated surfaces

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