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: db@engr.uky.edu* 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) i th l ll f lf bl d thi fil

Preparation of supported iron nanoparticlesSynthesis reaction:

5 ml NaBH4 (5.4M) solution drop-wisely

Water in oil micelle

N2in N2

out

Washed using methanol

CA acetone solution

Iron nanopartilces

Mixing

Iron naoparticles in Cellulose acetone solution

Ethanol bath

Casting

The weight content of iron is 6.6% by AA (Atomic Absorption).

TEM Characterization of pre-produced iron particles

1 µm

TEM bright field image of pre-produced iron particles

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

(Cm

ax =

1.8

3mm

ol/l)

containing 27 mg pure iron per vial

containing 80 mg pure iron per vial

Mixed-Matrix Membrane PreparationFe2+/

Ni2+ (aq)

Cellulose Acetate in Acetone

Phase Inversion

Dry Process Wet Process (nonsolvent gelation bath)Water or ethanol

Cellulose Acetate/Fe2+/Ni2+ Mixed-Matrix MembraneNaBH4 (aq

or ethanol)Reduction

Cellulose Acetate/Nanoscale Fe-Ni Mixed-Matrix Membrane

Meyer, Bachas, and Bhattacharyya, Env. Prog (2004)

M2+ + PAA-Na+ M2+-PAA + Na+

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)

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

Post coating with Ni or Pd

Ethylene glycol(EG)

A

10 20 30 40 500

5

10

15

20

25

30

35

40

Num

ber o

f Par

ticle

sDiameter (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.

Image of Fe/Ni particles Prepared in a TEM Grid(Ni post-Coated)

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 o

f Par

ticle

s

Diameter (nm)

5±0.8 nm

STEM-EDS Mapping (using JOEL 2010)

Fe Ni

Fe Ni

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)a

s ×ρ

m

k SA=0.0813±0.002 L·h-1·m2, R2=0.989

k SA=0.1395±0.006 L·h-1·m2, R2=0.983

k SA=0.0378±0.003 L·h-1·m2, R2=0.962

k SA=0.948±0.05 L·h-1·m2, R2=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 concentrationkSA: surface-area-normalized

reaction rate as: specific surface area ρm: mass concentration of

metalt: time

CakdtdC

msSA ρ−=

Material KSA (L·h-1·m2)

Nano Fe 2.0×10-3

Nano Fe/Ni (3:1)

0.098

Other source kSA*

Fe/Pd

Fe/Ni

* 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.

Effect of Ni content in Fe/Ni particles on KSA

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)

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)

Con

cent

ratio

n (m

M)

Biphenyl2,3,2',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

Dechlorination Study under Convective Flow Mode(PVDF-MF membrane & Fe/Pd nanoparticles)

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)

Con

cent

ratio

n (m

M)

2,2'-ChloroBiphenyl2-ChloroBiphenylBiphenyl

•22 mg Fe/Pd (Pd=0.4wt%) in PAA/PVDFmembrane (4 samples of membranes in stack)

•Membrane area = 13.5 cm2

•Membrane thickness = 125µm × 4•Membrane Permeability = 2×10-4 cm3cm-2bar-1s-1

•Pressure:0.3~4 bar

2,2’- Chlorobiphenyl Degradation

AcknowledgementsUS EPA- STAR Program Grant # R829621NSF-IGERT ProgramNIEHS-SBRP ProgramDow Chemical Co.Undergrads: UK--Melody Morris, Morgan

Campbell, Alabama--Cherqueta Claiborn