Membrane-Based Nanostructured Metals for Reductive Degradation of Hazardous Organics at Room Temperature
D. Bhattacharyya (PI)*, D. Meyer, J. Xu, L. Bachas (Co-PI), Dept. of Chemical and Materials Engineering and Dept. of Chemistry, University of Kentucky, and S. Ritchie (Co-PI), L. Wu, Dept. of Chemical Engineering, Univ. of Alabama
* email: [email protected] * phone: 859-257-2794
Project Officer: Dr. Nora Savage, US EPAEPA Nanotechnology Grantees Workshop
August 17-20, 2004
Functionalized Materials andMembranes(Nano-domain Interactions)
Ultra-HighCapacity MetalSorption (Hg, Pb etc)
Reactions and Catalysis (nanosized metals, Vitamin B12, Enzymes)
Tunable Separations(with Polypeptides)Hollman and Bhattacharyya, LANGMUIR(2002,2004); JMS (2004) Smuleac, Butterfield, Bhattacharyya, Chem. of Materials (2004)
Bhattacharyya, Hestekin, et al, J. Memb. Sci. (1998)Ritchie, Bachas, Sikdar, and Bhattacharyya, LANGMUIR (1999)Ritchie, Bachas,Sikdar, and Bhattacharyya, ES&T (2001)
*Ahuja, Bachas, and Bhattacharyya, I&EC (2004)
Why Nanoparticles?
• High Surface Area
• Significant reduction in materials usage
• Reactivity (role of surface defects, role of dopants such as, Ni/Pd)
• Polymer surface coating to alter pollutant partitioning
• Alteration of reaction pathway (ex, TCE -- ethane)
• Bimetallic (role of catalysis and hydrogenation,minimizing surface passivation)
• Enhanced particle transport in groundwater
Synthesis of Metal Nanoparticles in Membranes and Polymers
• Chelation (use of polypeptides,poly(acids), and polyethyleneimine)
– Capture and borohydride reduction of metal ions using polymer films containing polyfunctional ligands.
• Mixed Matrix Cellulose Acetate Membranes
– Incorporation of metallic salts in membrane casting solutions for dense film preparation. Formation of particles within the membrane occurs after film formation.
– External Nanoparticle synthesis followed by membrane casting
• Thermolysis and Sonication
– Controlled growth of metal particles in polymeric matrices by decomposition of metal carbonyl compounds thermally or by sonication.
• Di-Block Copolymers
– The use of block copolymers containing metal-interacting hydrophilic and hydrophobic segments provide a novel approach for in-situ creation of nanostructured metals (4-5 nm) in the lamellar space of self-assembled thin films.
Preparation of supported iron nanoparticles
The weight content of iron is 6.6% by AA (Atomic Absorption).
Water in oil micelle
5 ml NaBH4 (5.4M) solution drop-wisely
N2 in
N2 out
Washed using methanol
CA acetone solution
Iron nanopartilces
Mixing
Iron naoparticles in Cellulose acetone solution
Ethanol bath
Casting
Synthesis reaction:
TEM Characterization of pre-produced iron particles
TEM bright field image of pre-produced iron particles
1 m
TEM bright field image of CA membrane-supported iron nanoparticles
Change of chloride ions in aqueous phase (TCE degradation to Cl-)
0
0.2
0.4
0.6
0.8
1
0 10 20 30 40 50
Time, hr
C/C
max
(C
max
= 1
.83m
mol
/l)
containing 27 mg pure iron per vial
containing 80 mg pure iron per vial
Cellulose Acetate/Nanoscale Fe-Ni Mixed-Matrix Membrane
Fe2+/ Ni2+ (aq)
Cellulose Acetate in Acetone
Cellulose Acetate/Fe2+/Ni2+ Mixed-Matrix Membrane
Mixed-Matrix Membrane Preparation
NaBH4 (aq
or ethanol)Reduction
Phase Inversion
Dry Process Wet Process (nonsolvent gelation bath)Water or ethanol
Meyer, Bachas, and Bhattacharyya, Env. Prog (2004)
Mo + PAA
Mo M2+ + 2e-
R-Cl + H+ + 2e- R-H + Cl-
Chlorinated organics in water R-Cl
Selective Sorption
In Membrane
Metal Reduction
(Borohydride or electrochemical)
M2+ Recapture with membrane-bound PAA Carboxylic Groups
(loss of metals and metal hydroxide pptn. On Mo surface prevented)
M2+ + PAA-Na+ M2+-PAA + Na+
Mo: Nanosized Mo in membrane phase
Nano-structured Metal Formation and Hazardous Organic Dechlorination with Functionalized Membranes (with simultaneous recapture/reuse of dissolved metals).
CO
O-
CO
O-
CO
O-
PAA:Poly-amino acidOr Poly-acrylic acid
Nanoparticle Synthesis in Membrane (use of PAA)
* O S
O
O
*
Polyether sulfone (PES)
H2C CH
C
**
OH
O
Polyacrylic acid (PAA)
* C C
H
H F
F
*
Polyvinylidenefluoride (PVDF)
Dip Coating
Membrane support
PAA+Fe2++EG
NaBH4 solution
Crosslinked PAA-Fe2+
110 °C 3 hour
Uncrosslinked PAA-Fe2+
Nano Fe/Ni or Fe/Pd particles immobilized in membrane
Cross-section
HOOH
Ethylene glycol(EG)
Post coating with Ni or Pd
10 20 30 40 500
5
10
15
20
25
30
35
40
Num
ber
of P
arti
cles
Diameter (nm)
B
(A) SEM surface image of nanoscale Fe/M particles immobilized in PAA/MF composite membrane (reducing Fe followed by metal deposition) (100,000); (B) Histogram from the left SEM image of 150 nanoparticles. The average particle size is 28 nm, with the size distribution standard deviation of 7 nm.
A
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.50
5
10
15
20
25
30
35
40
Num
ber
of P
arti
cles
Diameter (nm)
Image of Fe/Ni particles Prepared in a TEM Grid (Ni post-Coated)
50.8 nm
Fe Ni
Fe Ni
STEM-EDS Mapping (using JOEL 2010)
Reducing Fe followed by Ni deposition
Simultaneous reduction of Fe and Ni
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2 2.5
Time (h)
C/C
0
Blank control
PAA/PES Membrane(no particles)
Fe/Ni synthesized in solution
Fe/Ni on membrane(simultaneous reduction of Feand Ni) Fe/Ni on membrane(reducing Fe followed by Nideposition)
TCE Dechlorination by Fe/Ni and Fe/Pd Nanoparticles in Membrane
Metal loading:45mg/40mLInitial TCE: 10µg/mlFe: Ni= 4:1 (in PES support)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 0.2 0.4 0.6 0.8 1 1.2
Time (h)
-Ln(
C/C
0)
as
m
k SA=0.0813±0.002 L∙h-1
∙m2, R
2=0.989
k SA=0.1395±0.006 L∙h-1∙m
2, R
2=0.983
k SA=0.0378±0.003 L∙h-1
∙m2, R
2=0.962
k SA=0.948±0.05 L∙h-1∙m
2, R
2=0.969
Surface-Area-Normalized Dechlorination Rate (wide variation of kSA showing the importance of surface – active sites and role of hydrogenation)
()Fe/Ni (simultaneous reduction);()Fe/Ni (Ni deposition on Fe);()Fe/Ni (solution phase)() Fe/Pd
C: TCE concentration
kSA: surface-area-normalized reaction rate
as: specific surface area
m: mass concentration of metal
t: time
Cakdt
dCmsSA
Material KSA (L·h-
1·m2)
Nano Fe 2.010-3
Nano Fe/Ni (3:1)
0.098
Other source kSA*
* From B. Schrick, J.L. Blough, A.D. Jones, T.E. Mallouk, Hydrodechlorination of Trichloroethylene to Hydrocarbons Using Bimetallic Nickel-Iron Nanoparticles. Chem.Mater. 2002, 14, 5140-5147.
Fe/Pd
Fe/Ni
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.2 0.4 0.6 0.8 1
Weight percent Ni
kS
A (
L h
-1 m
-2)
Effect of Ni content in Fe/Ni particles on KSA
Fe Ni
Initial TCE: 20mg/LReaction volume: 110mLFe/Ni in PVDF support (Posting coating Ni)
All experiments were performed in batch systems using nanosized Fe/Ni particles (Post coating Ni) immobilized in PAA/PVDF membrane.
Reactions of 2,3,2’,5’-Tetrachlorobiphenyl (PCB)
with Fe/Pd (~30 nm) in PAA/PVDF membrane
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 20 40 60 80 100 120 140
Time (Min)
Co
ncen
trat
ion
(mM
)
Biphenyl
2,3,2',5' Tetracholorobiphenyl
Metal loading:22mg/20mLPd = 0.4 wt%Initial organic concentration:8.4mg/L in 50% ethanol/water
Main intermediates at short time: 2,5,2’-trichlorobiphenyl, 2,2’-dichlorobiphenyl, 2-chlorobiphenyl
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 0.5 1 1.5 2 2.5
1/Jw×10-4 (cm3/cm2·s)
Co
nce
ntr
atio
n (
mM
)
2,2'-ChloroBiphenyl2-ChloroBiphenylBiphenyl
Dechlorination Study under Convective Flow Mode(PVDF-MF membrane & Fe/Pd nanoparticles)
•22 mg Fe/Pd (Pd=0.4wt%) in PAA/PVDF membrane (4 samples of membranes in stack)•Membrane area = 13.5 cm2
•Membrane thickness = 125m 4•Membrane Permeability = 210-4 cm3cm-2bar-1s-1
•Pressure:0.3~4 bar
2,2’- Chlorobiphenyl Degradation
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