hybrid composites of nano-sized zero valent iron and covalent organic polymers for groundwater...

Hybrid composites of nano-sized zero valent iron and covalent organic polymers

for groundwater contaminant degradation

Paul Mines1,2, Jeehye Byun2, Y. Hwang1, H. Patel2, H. Andersen1, C. Yavuz2

<8TH Annual Meeting of DWRIP 2014, January 30>

1 Department of Environmental Engineering, DTU, Denmark2 Graduate School of Energy, Environment, Water and Sustainability, KAIST, Korea

8th Annual meeting of DWRIP 30/01/2014

Introduction – Nano-sized Zero Valent Iron (nZVI)

acetylene ethene ethane

TCE

Ref: Daniel Cha, U. of Delaware

Extremely effective at degradinga wide variety of contaminants inwater sources• Chlorinated organics, azo dyes, pesticides, inorganic ions• Compounds are often not amenable to biodegradationReaction scheme for nZVI with chlorinated organics:


Introduction – nZVI Stabilization

Conventional technology – permeable reactive barriers (PRBs)• Limited by stability of ZVI in groundwater

• Fe0 aggregates together, forms large particles, settles out, becomes inactive

Widespread application requires that nZVI remains stable and maintains its reactivity• Applicable for in situ PRBs or ex situ pump-n-treat operations

PRB

Ref: EnviroMetal, Inc. Ref: PNF Nano-Engineering & Manufacturing Co.


Introduction – Covalent Organic Polymers (COPs)• Hybrid materials improving on conventional covalent organic

framework (COF) technology at lower cost.• No post-processing or cross-linking necessary

• Offer extremely high surface areas• Up to 600 m2/g

• Proven adsorbent for CO2 capture applications• Up to 5600 mg-CO2/g-COP (@200bar/318K)

(Patel et al., 2012)


COP ChemistryPolymer Core Molecule Linker Molecule Solubility

COP1 Triazine trichloride Piperazine Miscible in water

Solvent used:H2O

COP6 Triazine trichloride 4,4’-thiobisbenzenethiol Immiscible in water

Solvent used:N,N-Dimethylformamide(DMF)

COP19 Terephthaldehyde Melamine Miscible in water

Solvent used:H2O

COP60/61 Benzene tricarbonyl trichloride Not yet published Immiscible in water

---Solvent used:N,N-Dimethylformamide(DMF)


Overall Objectives

• Stabilization• Prove feasibility of COP materials as effective supporting and

stabilizing agents for nZVI

• Remediation of azo dyes• Poses significant environmental risk due to toxicity and widespread

global application• Acts as model pollutant for degradation of other recalcitrant chemicals

• Prove a synergistic effect of the composite material• Show effective decolorization of azo dye with COPs

• Combining adsorption from COP material and degradation from impregnated nZVI

• Eventual target halogenated organics (TCE, PCE, etc.)


Materials and Methods

1. Synthesis of nZVI impregnated COPs FeCl3 0.05 mol/L

- quantity in 20mL 0.162g

COP 2% (w/v)


NaBH4 0.15 mol/L


Impregnation Time 24 hours

Solution Filtration Yes

Reduction Time 30 minutes

Vacuum Drying Time @ 120°C

12 hours


Materials and Methods

2. Characterization Transmission electron microscopy (TEM) Inductively coupled plasma – mass spectrometry (ICP-MS)

Total iron content within composites X-ray diffraction (XRD)

Confirmation of presence of Fe0

BET surface area

3. Stabilization Test Optical absorbance at 508nm using UV-Vis spectrometer (Phenrat et

al., 2007)

4. Reactivity Test Azo-dye decolorization

- Acid Black I (60µM) / HEPES buffered (10mM)- Reaction solution: 1.5g composite/L dye solution


TEM Imaging

COP6/nZVI COP19/nZVI


Iron Contained in Composites (ICP-MS)

nZVI COP1 COP6 COP19 COP60 COP610.0

0.2

0.4

0.6

0.8

1.0m

g-Fe

/mg-

com

posi

te


Presence of Fe0 (XRD)

Pure nZVI COP19/nZVI

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 800

50

100

150

200

250

300

350

400

Fe0 @ 44.9°

Inte

nsity

2 (deg)

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 800

50

100

150

200

250

300

350

400

Inte

nsity

2 (deg)

Fe0 @ 44.9°


Composite BET Surface Area Analysis

168

37

600

9.1 8.8

72.1

17.3

332.4

8.9 5.9

COP1 COP6 COP19 COP60 COP610

100

200

300

400

500

600S

urfa

ce A

rea

(m2/g

)

Bare Polymer Composite (COP + nZVI)


Composite Stability Testing

Sedimentation Test• Optical absorbance @ 508nm

COP/nZVI composites show increased stability vs. pure nZVI

0 5 10 15 20 25 30 35 40 45 50 55 600.0

0.2

0.4

0.6

0.8

1.0

A/A

o

Time (minutes)

nZVI COP1 COP6 COP19 COP60 COP61


Acid Black I Decolorization Images

Alias: Naphthol blue blackMolecular Formula: C22H14N6Na2O9S2

Molecular Weight: 616.499 g/molPeak Absorbance (λmax): 618nm

COP1/nZVI

COP19/nZVI

COP60/nZVI

D.I.

D.I.

D.I.

t=0

t=0

t=0

t=30

t=30

t=30

+

+

1,2,7-triamino-8-hydroxynaphthalene-3,6-disulfonate

aniline

p-nitro-aniline p-phenylene-diamine


Dye Decolorization UV-Vis Spectra

COP1/nZVI• Combination of dye adsorption and

degradationCOP19/nZVI• Primarily dye adsorptionCOP60/nZVI• Little to no adsorption or degradation

300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780

0

1

2

3

Abs

orba

nce

Wavelength (nm)

Initial 1 2.5 5 7.5 10 15 20 30

300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780

0

1

2

3

Abs

orba

nce

Wavelength (nm)

Initial 1 2.5 5 7.5 10 15 20 30

300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780

0

1

2

3

Abs

orba

nce

Wavelength (nm)

Initial 1 2.5 5 7.5 10 15 20 30

COP1

COP19 COP60


Acid Black I - Peak Absorbance vs. Time

0 5 10 15 20 25 300.0

0.2

0.4

0.6

0.8

1.0C

/C0

Reaction Time (minutes)

COP1 COP6 COP19 COP60 COP61 Act. C


COP6: Polymer vs. Composite Decolorization

0 5 10 15 20 25 300.0

0.2

0.4

0.6

0.8

1.0C

/C0

Reaction Time (minutes)

Bare Polymer Composite (COP6 + nZVI)


Surface Area vs. Decolorization

COP1 COP19 COP6 COP60 COP610

50

100

150

200

250

300

350Water Miscible

Sur

face

Are

a (m

2/g

)

nZVI/Polymer Composite

Surface Area

1 - (C/C0)

Water Immiscible

0.0

0.2

0.4

0.6

0.8

1.0

1 - (

C/C

0)


Conclusions

nZVI/COP Synthesis• Successfully impregnated nZVI within the COP matrices (~10%)

Effective Stabilization of nZVI• Loading nZVI into the COP matrix proves much more stable than bare nZVI

Successful Azo Dye Decolorization• Depending on the COP, achieved decolorization in the form of adsorption,

degradation, or a combination of both

Wettability of the Polymer• Decolorization is highly dependent on the wettability of the COP material• Migration of the azo dye in the aqueous phase must be possible and depends on the

nature of the composite material

Surface Area of the Composite Material• Decolorization is also dependent on the total surface area of the nZVI/COP material


Thank you for attention

Any questions & comments?

hybrid composites of nano-sized zero valent iron and covalent organic polymers for groundwater...

Documents

annual meeting of dwrip

water solvent

korea slide

delaware slide

ndimethylformamide dmf

feasibility of cop materials

introduction nano

g cop2