Nanotechnology for Treatment of Contaminated Water
D. Bhattacharyya (speaker)*, J. Xu, S. Lewis, L. Bachas, B. Hennig, and D. Meyer
UK NIEHS-SBRP ProgramUniversity of Kentucky
Lexington, Kentucky 40506 USA
* email: [email protected]* phone: 859-257-2794
Joint NIEHS SBRP-WETP Technical Workshop April 3-4, 2008
Natcher Conference Center, NIH CampusBethesda, MD
Detoxification of Chloro-Organics, such as TCE, PCB (At Room Temperature)
Reduction pathway for Chlorinated Compounds
PCB →
BiphenylTCE → Ethane
Systems:Zerovalent metals (Fe), Bimetallic system (Fe/Pd, Fe/Ni), Polymer Platform
Oxidation of Chlorinated Compounds
Products: CO2 , Organic Acids,Potential chloro-intermediates
Systems : Chelate Modified Fenton Reaction
On-site enzymatic H2 O2 generation
Nanosiz
ed M
etals Hydroxy-Radical
& Chelates
CombinedPathway
H2 O2
Fe2+ + nontoxic chelate
TCE, PCB, etc
Ground level
Groundwater Remediation Using Combined Strategies For Reduction and Oxidation
Fe, Fe/Pd, Fe/ Ni
Reduction Oxidation
Groundwater
Dechlorination Products and/or Intermediates
Ethane
Organic Acids and/or CO2
Non-dissolved CO2
Enhanced downstream bio- attenuation of products
because of biodegradable chelate (gluconic acid, citrate)
Detoxification of TCE and PCBMetal Nanoparticles
Solution Phase
Synthesis
Polymer Domain
Fe0 Phase Inversion
Ion- Exchange
Supported*
Fe0, Fe0/Ni, or Fe0/Pd
*eliminates worker exposure
(Bimetallic via Postcoating)
TCE
Ethane
Fe0/Ni, Fe0/Pd
NaBH4
NaBH4
PCB
Biphenyl
Background (membrane-based nanoparticle synthesis)
•Prevent particles agglomeration by polymer network
•Control particle size and assembly •Convective flow•Recapture of dissolved metal ions
Fe nanoparticles synthesized in solution phase. Wang et al., Environ. Sci. Technolo. 1997, 31, 2154
Ag nanoparticles in PAA/PAH multilayer films. Wang et al., Langmuir 2002, 18, 3370
Nanoparticle synthesis in aqueous phase
Nanoparticle synthesis in membrane phase
Particle agglomeration and growth in solution without stabilizing agent
+++
+
+++
++
++
++
++ +
+
+
+
reduction
++++
++
++
++
reduction growth agglomeration
NaBH4
Cu nanoparticles in COOH functionalized polyimide film. Thermal process with H2 Ikeda et al., J. Phys. Chem. B 2004, 108, 15599
Synthesis of Nanostructured Metals in Functionalized Polymers for Detoxification of Chlorinated Organics
Support Membrane (MF, UF): PVDF, PES
Dip-coating PAA or In- situ polymerization of acrylic acid
PAA functionalized membranes
FeCl2 , pH = 5
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+Element Atom%C (K) 64.21 F (K) 22.17Fe (K) 3.01 O (K) 10.62
CO
O
Fe2+
C O
O
SEM-EDX
Pd/Ni coating
TEM-EDXTEM image
Cou
nts
Energy (keV)108642
Pd
Fe
FeFe
O
C
Cu
Cu
Fe = 97.9 wt% Pd = 1.9 wt%
Core/Shell structure
50 nm
Fe Pd
STEM-EDS Mapping
NaBH4
Pore size: 50~500 nm
* C C
H
H F
F* H2C CH
C
**
OH
O
Polyvinylidenefluoride (PVDF)
Pd or Ni
Polyacrylic acid (PAA)
50 nm
EDS Mapping
HRTEM
Fe
Pd
Fe/Pd Nanoparticles Characterization
Electron diffraction pattern
Pd
Fe
{110}
{200}
{210}{222}
Pd
Fe/Pd (Pd = 2.3 wt%) nanoparticles
Body center cubic (BCC) crystal structure of Fe0
(Suslick, Fang, Hyeon, J. Am. Chem. Soc. 118, 11960-11961, 1996)
0.0 0.5 1.0 1.5 2.0 2.50.00
0.04
0.08
0.12 TCE
Con
cent
ratio
n (m
M)
Time (h)
Ethane Mass balance Cl-/3
0.0 0.2 0.4 0.6 0.80
2
4
6
8
10
-Ln(
C/C
0)/ρ
m
Time (h)
kobs = 11.2 l h-1 g-1
TCE Dechlorination by Nanoparticles
Fast and complete degradationto ethane, no toxic intermediates
0 1 2 3 50 510
2
4
6
8
10
12
TCE
con
cent
ratio
n (m
g/L)
Time (h)
TCE spiking
Longevity of Nanoparticle Reactivity
•Fe/Ni (Ni =25 wt%) in PAA/PVDF membranes •Metal loading: 0.08g/20ml•16 cycles of TCE dechlorination
Metal loading:4.5mg/20mLFe/Ni (Ni = 25 wt%)
:Pd/NiSecond metal
Catalytic hydrodechlorination
Fe2+
H*
EthaneTCE
Room temperature
?
Dechlorination of Polychlorinated Biphenyls (PCBs)
PCB 77 (3,3’,4,4’) dechlorination by Fe nanoparticles at room temperature (from Lowry, et al., Environ. Sci. Technol. 2004, 38, 5208)
Metal loading: 4 g/LkSA : 6.3×10-8 L h-1 m-2
t1/2 : 73 daysNegligible biphenyl formation
0.0 0.5 1.0 1.5 2.0 2.50.000
0.015
0.030
0.045
0.060
Con
cent
ratio
n (m
M)
Time (h)
PCB77 (3,3',4,4') PCB37 (3,4,4') PCB35 (3,3',4) PCB15 (4,4') PCB12and13 (3,4' and 3,4) PCB11 (3,3') PCB3 (4) PCB2 (3) Biphenyl Carbon Balance
Metal loading: 0.8 g/LPd = 2.3 wt%kSA : 0.11 L h-1 m-2
t1/2 : 20 minComplete biphenyl formation
PCB 77 (3,3’,4,4’) dechlorination by membrane based Fe/Pd (Pd=2.3 wt%) nanoparticles at room temperature
Cl Cl
Cl
Cl
PCB 77 (3,3’,4,4’)
Aspects to Address for Successful TCE Dechlorination Using Direct Injection of
Nanoparticle Systems• What composition and metal loading are necessary for
rapid and efficient TCE dechlorination? (batch data)• Will the presence of non-chlorinated chemical species
present in Paducah groundwater and soil alter the performance of Fe-based nanoparticle dechlorination systems? (batch and column experimental data)
• What impact, if any, will dissolved oxygen have on dechlorination kinetics? (batch data)
• What type of mobility will nanoparticles have while moving within plumes? (theoretical modeling)
Dechlorination of TCE in Deoxygenated Paducah Water Using Fe/Pd Nanoparticles with Variable Metal Conditions:
C0 = 20.5 mg/L; pH = 5
0.000.100.200.300.400.500.600.700.800.901.00
0 0.2 0.4 0.6 0.8 1 1.2
Time (h)
TCE,
C/C
0
1 wt% Pd; 1.0 g/L
1 wt% Pd; 0.24 g/L
0.5 wt% Pd; 1.0 g/L
1 wt% Pd ~ 0.5 monolayer
Packed Column Studies for Simulated Groundwater Injection
3-in ID Tube
4ft
1’
1.5’
2.0’
2.5’
3.0’
0.25”Sample
Port(PTFE)
0.25”Outlet
(PTFE)
0.5’
3.5’
3-in ID Tube
4ft
1’
1.5’
2.0’
2.5’
3.0’
0.25”Sample
Port(PTFE)
0.25”Outlet
(PTFE)
0.5’
3.5’
Preliminary Results
Column Depth (ft) C/Co0.5 0.1852 0.080
Column Flowrate = 260 ft/day
Fe/Pd (0.5 wt%) = 0.4 g/L
Initial TCE = 46 ppmCirculation Time = 4 h
Liquid Volume = 2.25 L
Paducah Gravel
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5
Column Depth, (ft)
TCE
(C/C
0), C
l- (C
/CM
ax)
24 h TCE48 h TCE24 h Cl-
Packed Column Studies: Flowrate = 82 ft/day; Metal Loading = 0.46 g/L Fe/Pd (0.5 wt%);
C0 = 25 ppm TCE; pH =7.0
Examination of Material Usuage for the Reduction of 400 ppb TCE Using Fe/Pd Nanoparticles
Time Basis 24 h kSA 1.30E-01 L.m-2.h-1 (Fe + 0.5 wt% Pd)Treatment Diameter 400 ft Fe/Pd loading 0.25 g/LTreatment Depth 20 ft mass Fe/Pd 9,433 g/h = 20.753 lbs/hAsssumed Porosity 0.4 Surface Area 30 m2 metal/gTreatment Area 125,664 ft2 Loading 7.5 m2 metal/LTreatment Volume 2,513,274 ft3
Treatment C.S. Area 3,200 ft2 TCE 400 ppbGroundwater Velocity 10 ft/day
0.42 ft/hr CTCE @ 1h 0.000 ppbVolume per hour 1,333 ft3/h TCE reacted 1.15E-01 moles/h
37,733 L/h
Fe:TCE ratio 4:1moles Fe consumed 4.59E-01
mass Fe consumed 25.66 g/h0.056 lbs/h
Fe remaining 9,407.67 g/h20.697 lbs/h unused
Note: one can treat 38000 liters of water with 26 g of nano Fe particles
Detoxification by Chelate-Based Modified Fenton Reaction
• Controlled release of Fe2+
• Prevent Fe(II) oxidation • At near neutral pH, prevent Fe(OH)3 precipitate by
complexing with Fe(III)• Have a better H2 O2 utilization during the reaction• Hydroxy radical and superoxide* radical formation near
neutral pH operation• Potential biodegradation enhancement• Chelate can also be immobilized in nano-particles
Why Chelate-Based Modified Fenton’s Reaction?
*Superoxide Radical Formation: •+→+• 2222 HOOHOHOH−+ •+→• 22 OHHO
Required Materials for Chelate-Based Modified Fenton Reaction
http://www.hort.purdue.edu/ext/senior/ fruits/orange1.htm
http://www.drugstore.com/popups/largerphoto/def ault.asp?pid=77653&catid=39521&size=300&trx
=29888&trxp1=77653&trxp2=1
http://pics.drugstore.com/prodimg/738 64/200.jpg
Citrate Ferrous Sulfate Hydrogen Peroxide
0
1
2
3
4
5
0 10 20 30 40 50H2O2 Consumed (mmol)
TCE
Deg
rade
d (m
mol
)
L/Fe = 3.0 pH = 5.2
L/Fe = 0.5 pH = 6.8
L/Fe = 0.0 pH = 7.4
TCE Degradation as a Function of Peroxide Consumed for Varying Citrate (L)-to-Fe Ratios Showing the Potential Reduction in Peroxide Needs for
Chelate-Based Systems
Increasing L
The Challenges of DNAPL1.) TCE droplets dispersed in the aqueous phase will act as a source of TCE and shrink as mass is lost to the aqueous phase. The mass transfer between phases may have substantial impact on the observed reaction time for both oxidation and reduction.
TCE Droplet
Saturated Aqueous Phase (Reaction Zone)
TCE Droplet
2.) If DNAPL droplets are dispersed within soil and rock, they may require much greater reaction times for direct treatment. To overcome this problem, surfactant addition can potentially be used to mobilize the DNAPL from the sediment. Laboratory packed columns operating under trickle-flow can be used to examine this phenomenon.
Oxidation or ReductionOxidation
or Reduction Products
Dispersed DNAPL Droplets
DNAPL Extraction using surfactant injections
Dispersed DNAPL Droplets
Chelate-Modified Fenton Reaction (initial pH=7.0, no further adjustments made) Using DIUF Water with DNAPL (2000ppm
TCE) and Varying Fe(II):H2 O2 Molar Ratio
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Time (hr)
TCE
/TC
E 0
0.0
0.2
0.4
0.6
0.8
1.0
Cl- /C
l- max
1:1:1:4 TCE 1:1:1:8 TCE TCE Control1:1:1:4 Cl- 1:1:1:8 Cl- Cl- Control
TCE droplets
Acknowledgements
• NIEHS-SBRP Program
• DOE-KRCEE Program
• UK Environmental Research and Training
Laboratory (ERTL) (John May & Tricia Coakley )
• UK Electron Microscopy Facility (Dr. Alan Dozier)
Extra slides
Background (reductive dechlorination at room temperature)
RCl + H* RH + Cl-
Fe0 Fe2+ + 2e-
Fe0 + 2H+ Fe2+ + H2
Reaction mechanism: electron transfer(Matheson et al., Environ. Sci. Technol. 28, 2045-2053, 1994)
(Meyer and Bhattacharyya, J. Phy. Chem, 2007;Xu et al, J.Nanopar.Res. 7, 449-467, 2005)
Fe2+
e-
RCl + H+
Fe0
RH + Cl-
RCl + 2e- + H+ RH + Cl-
RCl + Fe0 + H+ Fe2+ + RH + Cl-
Cl
ClCl Cl
Cl
ClClCl
Cl
ClCH2H2C
(Xu & Bhattacharyya, Environ. Prog., 24, 358, 2005)
Fe2+
e-H2 O
RH + Cl-
Fe0
Pd0
H2
H*
RCl
Bimetallic system
Single Fe0
system
Reaction mechanism: catalytic hydrodechlorination
H2 + Pd Pd-H + H*
Cl
ClCl
CH3H3C
Technology Enhancement: On-site Generation of Chelate and H2 O2
GOx (Oxidized)
FADGLUCOSE
GOx - GlucoseGOx
(Reduced)FADH2
H2 O2
GLUCONIC ACID
HYPOTHESISGluconic acid produced by enzymatic reaction would act as a chelate in Fenton
reaction, and thus allow degradation of TCE & PCBs near neutral pH
On-Site source of peroxideand chelate will eliminate
the need for concentrated chemical Storage by using simpleGlucose as a substrate
MOTIVATION
O2