1. Chemical Security Program The Role of Chemistry and Materials Science in Advanced Water Treatment

2. The Role of Chemistry and Materials Science in Advanced Water Treatment

3. Materials Science is an Essential Part of Water Treatment Infrastructure
Introduction
Water treatment processes
Materials science for water infrastructure
Membrane technology- polymeric
Micro and ultrafiltration (MF and UF)
Nanofiltration and reverse osmosis (NF and RO)
Recent RO membrane advances

4. Materials Science has a Dramatic Effect on Water Treatment Infrastructure
Glass reinforced plastics - corrosion
Pump coatings - friction reduction
Pipe lining – trenchless technology
Composite pumps – corrosion resistant
Steel alloys (Duplex SS)- corrosion resistant
Polymers, resins, additives- treatment
Polymeric membranes- porous: water purification, nonporous: desalination- pressure driven
Source : U.S. Filter

5. Membranes have Revolutionized Water Treatment

6. Membrane Separation Spectrum
Dissolved salts Nonporous
Suspended solids/ DOM Porous
Virus
Bacteria
Porous: Filtration by size - molecular weight cutoff (MWCO).
Nonporous: Solution diffusion separation – hydrated ions.
Removal: Salinity can be reduced only by RO/NF membrane treatment.
The Future of Desalination in Texas:Texas Water Development Board 2,(2004)
Alyson Sagle and Benny D. Freeman,

7. Basic Water Treatment Removes Particles and Dissolved Organics
Coagulation
Flocculation
Sedimentation and or filtration
Coagulant
Removal of particles and natural organic matter (NOM), color, disinfection byproducts (DBP), iron, manganese, arsenic, taste, odor.
Granular activated carbon can be used as a filter and adsorber, but regeneration may be different than sand media.

8. Microfiltration (MF) and Ultrafiltration (UF) can be used Instead of Sand Filters
Coagulant
Microfiltration or Ultrafiltration
concentrate
Flocculation
Coagulation
Membrane filtration normally uses hollow fiber bundles that can be submerged or pressurized.
These membranes can be air scoured , backflushed and cleaned and are not usually sensitive to chlorine.

9. Hollow Fiber Units Consist of Tube Bundles (UF-MF)
Asymmetric membranes are formed by phase inversion and produces anisotropic material.
Membrane Polymers
Polysulfone (PSF),
Polyethersulfone,
Poly(vinylidene fluoride),
Polyacrylonitrile,
Polypropylene.
Pressurized in housing
Submerged in cassette
Source : Pall
Source: Zeeweed

10. UF and MF Membranes can be “Inside-out” or “Outside in”
Mean pore size ~ size rating of filter ( micron)
Lumen
Source:
Koch Membranes
Permeate
Feed
Porous membranes can be backflushed and cleaned.
Skin

11. Primary Difficulty with Membranes is Fouling
Dead-end membrane operation
Cross-flow membrane operation
feed permeate
feed ∆P ∆P
permeate
Crossflow operation scours the surface and reduces stagnation near membrane surface.

12. Non-porous Membranes: Nanofiltration, Reverse Osmosis-thin Film Composite (TFC)*
thin, dense polymer coating on porous support (composites)
Surface morphology
Journal of Membrane Science, 158 (1999) Seung-Yeop Kwak, Dae Woo Ihm
Thin ( nm) polyamide membrane
Porous support (polysulfone UF membrane)
Woven mechanical support
* Discussion will not focus on cellulose acetate asymmetric membranes

13. Spiral Wound Membrane has Multiple Flat Sheet “leafs”
2007 EDS Conference, Halkidiki, Greece
Craig Bartels*, Mashiko Hirose, Hiroki Fujioka
*Hydranautics

14. Reverse Osmosis Primarily Uses Polyamide TFC Membranes
saline feed
pre-treatment
high pressure pump
post-
treatment
fresh
water
concentrate disposal
membrane
RO Plant
concentration dependent,
membranes susceptible to fouling,
pre-treatment required,
polyamide membranes degraded by Cl2.
dense polyamide membrane
porous polymer
mechanical support
Thin film composite membrane
polyamide

15. Reverse Osmosis Membrane Performance Measured by Four Factors
Salt rejection,
Water permeability,
Fouling (multifaceted),
Chlorine tolerance.
Salt Rejection
Normalized water permeability m3/(m2 bar day)
Journal of Membrane Science, 370(2011) Kah Peng Lee, Tom C. Arnot, Davide Mattia

16. Active Research Topics in RO Membrane Science and Desalination
Modification of PSF substrate
Increase hydrophilicity
Control of interfacial polymerization
Crosslinking
Membrane thickness
Increased chlorine tolerance
Surface post treatment
Modify surface charge
Membrane morphology
Surface roughness
New thin film nanocomposite studies
Polymer with zeolite, Ag, TiO2
Journal of Membrane Science, 370 (2011) Kah Peng Lee, Tom C. Arnot, Davide Mattia
J. Mater. Chem., 20 (2010) 4551–4566. Dan Li and Huanting Wang

17. Materials Science has Provided Major Breakthroughs in Water Treatment
Energy consumption and membrane costs have been reduced by new membrane formulations.
Journal of Membrane Science, 370 (2011) Kah Peng Lee, Tom C. Arnot, Davide Mattia

18. Membrane Surface Hydrophilicity Enhanced by Surface Modification
Surface modification leads to decrease in contact angle;
Less fouling potential, somewhat reduced water permeability
Contact angle (°)
Coating solution (mg/L)
Journal of Membrane Science 371 (2001) Sanchuan Yu, Zhenhua Lu, Zhihai Chen, Xuesong Liu, Meihong Liu, Congje Gao

19. Membrane Smoothness has an Effect on Membrane Fouling
Smoother membrane surface leads to less fouling
Journal of Membrane Science188 (2001) Eric M. Vrijenhoek, Seungkwan Hong, Menachem Elimelech

20. Membrane Degradation by Chlorine
Thin film composite membrane
dense polyamide membrane
porous polymer
mechanical support
Membrane degradation proceeds by chlorination of the amide followed by ring chlorination
Journal of Membrane Science, 300 (2007) Guo-Dong Kang, Cong-Jie Gao, Wei-Dong Chen, Xing-Ming Jie, Yi-Ming Cao, Quan Yuan

21. Chlorine Tolerant Membranes Being Studied
A new polymer formulation holds promise as a chlorine tolerant RO membrane.
Angew. Chem. 120 (2008), 6108 –6113.
Ho Bum Park, Benny D. Freeman, Zhong-Bio Zhang, Mehmet Sankir, James E. McGrath

22. Conclusion
Polymer science and composite fabrication have lead to increased use of membranes and advanced materials in water treatment.
Microfiltration and Ultrafiltration membranes have provided compact, efficient means of removing suspended solids and wastewater contaminants.
Nanofiltration and RO membranes provide lower energy alternatives for water desalination.