Directions...
-Charged PS layer -Fully aromatic -Glut. X-link MPD
Directions...
Incorporation of catalyts in membranes
To Increase the Hydrophilicity of TFC Surfaces...
(independent variables)
Bacterial Adhesion
(dependent variable)
Material Matrices...
Hydrophobicity & Pore Aspect Ratio
A
Flux Thickness Charge
B
C
D G
E H
F I
Hydrophobic Roughness
Thrust 2 - Desalination
"Advanced Membrane Materials for Water Treatment"
Harry Ridgway, Res. Director Orange County Water District Fountain Valley, California & Robert L. Riley, President Separation Systems Technology San Diego, California
Correlation of Membrane Surface Properties with Bacterial Attachment
Multivariate Models
MLR Analysis PC Analysis Cluster Analysis ANN Analysis
Membrane Properties
Popular Membrane Materials...
Asymmetric Cellulose Acetate General Properties...
•random, helical, non-X-linked •dense, smooth, neutral surface •low flux/high salt rejection •poor organics rejection •chlorine tolerant •low fouling tendency •can be biodegraded
(Polyamide Layer)
How are modern TFC membrane materials made?
Organic Phase (Heptane, etc.)
+ Acid Chloride
Cross-Link or Extension
Cross-Link or Extension
-new materials (e.g., CPTC)
•Enhanced flux & solute rejection
-increased cross-linking; catalytic membranes
-More X-linking -Tri-amines, etc. -Stereochemistry -Other polymers?
Advanced Materials for Water Purification
Background...
Modern water treatment is rapidly becoming dependent on membranes.
Bio-organic fouling is the major problem with the current generation of membrane separations (Example = biofouling). Opportunities exist for innovation in the design of improved membrane materials for water purification.
Re-Assembly
a marine gliding bacterium (Ridgway et al. 1977. J. Bacteriol.)
Pore-Like Structure
•Transport? •Stability?
Self-assembled crystalline protein-lipid arrays
PA Layer Porous PS Polyester Support
Kishore Rajagopalan [kishore@]
Self-Assembling Renewable Surfaces...
Isolation & Purification
Flexibacter polymorphus
Surface Modifications... -smooth, hydrophilic, neutral, mobile, renewable Anti-fouling Surfaces
Directions...
Chemical Directions... Resistance Catalytic Structural Surfaces Integrity
Stanford
Catalysis Catalytic Membranes TFCs
UIUC
ACFs, Macrocycle Gates, Hyperbranched PEIs, etc.
Clark-Atlanta
SST Synergies & Collaborations...
Surface-Modified TFC Membranes
2. Greater physico-chemical integrity 3. Improved flux and solute rejections
The Approach...
Bacteria and organics respond to a host of membrane surface properties. A multi-variate approach is needed to identify which properties of membranes contribute to bio-organics adsorption.
Biofilms & Oxidation Studies
Surface-Active Materials for Disinfection
Novel Materials & Processes for Water Purification
Pilot-Scale Studies & Demonstrations Applications R&D & Evaluations
X X X X X
.
Catalyst(s)
(Pd, PEIs, etc.)
PA Layer
Porous PS Polyester Support
Pure water
Mobile Membrane Surfaces...
+
Magnetic Particles
Popular Membrane Materials...
Polyamide Thin-Film Composites (TFCs) General Properties...
•random, X-linked •rough, charged surface •high flux/salt rejection •good organics rejection •chlorine sensitive •high fouling tendency •not biodegradable
2. PhysicoChemical 1 Integrity
De-lamination PA PS Chlorine Attack
2
3
Swelling
The Challenge...
...is to design a new generation of advanced membrane materials having... 1. Low-fouling surfaces
PS Support
AFM Image of PA Surface
AFM Image of PA Surface
The Issues...
1. Bio-organic Fouling
Molecular Adsorption
-Flux loss -Solute passage
Flux & Organics Rejection
Potential applications
• • Molecular ‘fly-paper’ for bacteria Spontaneous entrapment of bacteria in tubules
Gerard C. L. Wong et al., Science 288, 2035-2039 (2000)
Flux & Pore Diameter
SPEES-PES...
Polymer A
SO3H CH3 C CH3
polysulfone (PS)
Polymer B
O O n O O 1 = S =
O O S O =
+
O
O
=
= S O =
O
5
sulfonated polyether-ethersulfone/polyethersulfone (SPEES/PES) (sulfonation number = SPEES/PES = 1/5)