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) 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

Acknowledgements US EPA- STAR Program Grant # R829621 NSF-IGERT Program NIEHS-SBRP Program Dow Chemical Co. Undergrads: UK--Melody Morris, Morgan

Campbell, Alabama--Cherqueta Claiborn