nanoscale zero-valent iron: a new technology for groundwater remediation? richard crane school of...

Nanoscale zero-valent iron: a new technology for groundwater remediation?

Richard Crane School of Civil and Environmental Engineering, University of New South Wales

[email protected]

Richard Crane, International Association of Hydrogeologists Presentation, 07/05/13

Richard Crane, Interface Analysis Centre. IOM3 Young Persons Lecture Competition, 3/02/10

Contents

My background and research interests

Why study environmental engineering?

Why research engineered nanoparticles?

Why zero-valent iron?

Hydro-geochemical characterisation of a contaminated mine site, SW Romania

Batch sorption experiments using the mine water

Improving the physio-chemical composition of nano-Fe0

Industrial implications

My concurrent and future work at UNSW



My background

Grew up in Dorset, England

BSc Geoscience, University of Bristol, 2004 – 2008PhD Geochemistry, University of Bristol, 2008 – 2012 Postdoctoral Research Fellow, University of Bristol, 2012 – 2013 Research Fellow, University of New South Wales, 2013 – present

Research interests:

Geochemistry and hydrology of groundwater systems

Applications include: environmental engineering; water quality and resource protection; mining and mine site management; waste management; and the use of engineered nanomaterials for environmental applications


Why study environmental engineering?


A side effect of our industrial success, the majority of which has occurred since the industrial revolution in the 1800’s.

The type of emissions has changed in the last 50-60 years with pollution from complex chemicals, dense non-aqueous liquid phases (DNAPLs) and radioactive metals.UNICEF/WHO. 2008. www.who.int/water_sanitation_health/monitoring/jmp_report_7_10_lores.pdf

Pollution by definition is toxic! WHO estimate that is contributes to 88% of the global burden of disease


Why study engineered nanoparticles – its all about their size!


Nanomaterial is defined as a material with at least one dimension <100nm

• A pin head: 2 mm = 2,000,000 nm• A human hair: 100 µm = 100,000 nm• A red blood cell: 10 µm = 10,000 nm• An E. Coli bacteria cell: 0.2 µm = 200 nm• A Rhinovirus (common cold): 25 nm• A DNA strand (width): 2 nm• A Glucose molecule: 1 nm

High surface area to volume ratioQuantum size effectsPore network penetration even for low k systemsSubsurface deployment as a colloidal suspension

Unique deployment mechanism for a sorption agent

Conventional PRB Nanoparticle injection

Crane, R A, Scott, T B. (2012) Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology. J Haz.Mat.. 211, 112–125.



Why zero-valent iron?

Strong reducing agent

High sorption capacity

Non toxic

Cheap

Proven as effective for the reductive transformation of a wide variety of heavy metals, radionuclides, chlorinated organics, inorganic anions, and other harmful chemicals….




Deployment mechanism depends on the type of contaminant

Metal and metalloid contaminant remediation – immobilisation via sorption (adsorption, complexation, co-precipitation) and/or chemical reduction

Organic contaminant remediation – reductive transformation



Remediation type Remediation Technology Limitation

Ex-situ Pump-and-treat A, B, D

Excavation and disposal D, E

In-situ physical In-situ flushing N/A

Hydraulic fracturing N/A

In-situ chemical Permeable reactive barriers A, B, D, E

Chemical oxidation C

Nanoscale zero-valent iron injection

In-situ electrical Solidification, Stabilization and vitrification A, B, D, E

Electrokinetic processes A, B, D, E, F

In-situ biological Enzymatic remediation A, B, C, F

Phytoremediation A, B, C, F

Mycoremediation A, B, C, F

Microbial remediation A, B, C, F

Limitations

A= Lack in emplacement versatility

B= Long time lag

C= Only appropriate for specific contaminants

D= Expensive

E= Invasive

F= Low yield

Environmental engineering techniques


Thesis title: Sorption of uranium onto nanoscale zero-valent iron particles


Research goals:

Characterise the mechanisms and kinetics of uranium uptake onto nanoscale zero-valent iron

Application:

Determine the suitability of iron-based nanomaterials for the treatment of uranium contaminated waters and waste effluents

1. Hydro-geochemical characterisation of a contaminated site in SW Romania

2. Sorption experiments using natural and synthetic groundwater

3. Linking the recorded corrosion and contaminant uptake mechanisms to potential physico-chemical improvements for the different iron-based nanomaterials

NATO and Royal Society funded fieldwork in SW Romania


200 miles

50 miles


Chemical species Concentration (mg L-1)

Metals

Cu 0.023

Fe 0.043

Mo 0.045

U 0 - 10

Ligands

Cl- 35.01

HCO3 - 1041.10

F- 0.19

NO3- 30.80

PO43- 0.35

SO42- 0.25

Organics 12.72

Richard Crane, Interface Analysis Centre, 19/11/10

Geochemical analysis of the contaminated groundwater

K. V. Ragnarsdottir and L. Charlet. Uranium behaviour in natural environments. ISBN: 0-903-05620-8. Environmental mineralogy – Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management. Mineralogical Society Series. 9 (2000) 245-289.

U(IV) = insoluble

U(VI) = soluble


Batch sorption experiments in vadose and phreatic zone conditions

Scott, T B, Popescu, I C, Crane R A, Noubactep C. (2011). Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants. J Haz.Mat. 186(1):280-287.Crane, R A., Dickinson, M., Popescu, I C., Scott, T B. (2011) Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water. Wat. Res. 45(9), 2931-2942.Crane, R A, Scott, T B. (2012) Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology. J Haz.Mat.. 211, 112–125.Crane, R A., Scott, T B. (In Press) The removal of uranium onto nanoscale zero-valent iron particles in anoxic batch systems. J Haz.Mat.


Scott, T B, Popescu, I C, Crane R A, Noubactep C. (2011). Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants. J Haz.Mat. 186(1):280-287.Crane, R A., Dickinson, M., Popescu, I C., Scott, T B. (2011) Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water. Wat. Res. 45(9), 2931-2942.Crane, R A, Scott, T B. (2012) Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology. J Haz.Mat.. 211, 112–125.Crane, R A., Scott, T B. (In Press) The removal of uranium onto nanoscale zero-valent iron particles in anoxic batch systems. J Haz.Mat.


Scott, T B, Popescu, I C, Crane R A, Noubactep C. (2011). Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants. J Haz.Mat. 186(1):280-287.Crane, R A., Dickinson, M., Popescu, I C., Scott, T B. (2011) Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water. Wat. Res. 45(9), 2931-2942.Crane, R A, Scott, T B. (2012) Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology. J Haz.Mat.. 211, 112–125.Crane, R A., Scott, T B. (In Press) The removal of uranium onto nanoscale zero-valent iron particles in anoxic batch systems. Env. Sci. Tech.


Crane, R A., Dickinson, M., Popescu, I C., Scott, T B. (2011) Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water. Water Research. 45(9), 2931-2942.Crane, R A., Scott, T B. (In Press) The removal of uranium onto nanoscale zero-valent iron particles in anoxic batch systems. J Haz.Mat.

What is causing the re-release?


U(IV) = insoluble

U(VI) = soluble


What is causing the re-release?

U4f XPS spectra for nano-Fe0 after 24h reaction


By what mechanism is U6+ remobilised?


Chemical reduction or complexation?


Industrial/environmental implications

With ligands such as carbonate ubiquitous within the environment………

Previous studies using chemically simple systems have largely overestimated the performance of nanoscale iron for the treatment of environmental waters.

Contaminant re-release after a period of “apparent remediation” is a significant issue which may limit the development of zero-valent iron nanoparticles as a new technology for in-situ water treatment.

Zero-valent iron nanoparticles are only appropriate for the treatment of uranium in oxygen bearing waters if secondary methods (geotextile, bentonite, etc.) are applied to prevent oxygen ingress.

With sorption and/or chemical reduction a reversible process it is likely that the results from the current work is applicable to all heavy metals and radionuclides.

Methods are sought to improve the performance of nanoscale zerovalent iron for the remediation of chemically complex and/or oxygenated waters


TEM, XRD and XPS provide insight into the required improvements!



Improvement options:

•Size

•Modify nanoparticle structure (crystallinity, grain size, oxide thickness, etc.) and/or surface chemistry (oxide phase and stoichiometry, oxide conductance, abundance of impurities, etc.)

•Add dopent material that would act to improve the corrosion properties of the nanoparticles – noble metals (Ni, Pd, Pt, Ag, etc.)


Standard and vacuum annealed nanoparticle were analysed using BET, SEM, TEM, XPS, XRD, SIMS, STEM.

Option 1: Vacuum annealing

Scott, T. B., Dickinson, M., Crane, R,A., Riba, O., Hughes, G., Allen, G. (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles. Journal of Nanoparticle Research. 12(5), 1765-1775.Dickinson, M., Scott, T. B., Crane, R,A., Riba, O., Barnes, R.J., Hughes, G., (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nickel nanoparticles. Journal of Nanoparticle Research. 12(6), 2081-2092.


Results: TEM, XRD and XPS

Scott, T. B., Dickinson, M., Crane, R,A., Riba, O., Hughes, G., Allen, G. (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles. Journal of Nanoparticle Research. 12(5), 1765-1775.Dickinson, M., Scott, T. B., Crane, R,A., Riba, O., Barnes, R.J., Hughes, G., (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nickel nanoparticles. Journal of Nanoparticle Research. 12(6), 2081-2092.


Results: in-situ XPS

19.0 m2 g-1 4.8 m2 g-1

As-formed Vacuum annealed

Scott, T. B., Dickinson, M., Crane, R,A., Riba, O., Hughes, G., Allen, G. (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles. Journal of Nanoparticle Research. 12(5), 1765-1775.


an increase in the Fe0+Fe2+/Fe3+

and the Fe2+/Fe3+ content of the bulk metallic core and oxide respectively;

migration and/or volatilisation of impurities;

improvement in the crystallinity of the bulk metallic core and oxide;

thinning and dehydration of the oxide

Fe0 + 2Fe3+ → 3Fe2+ E0 = 1.21 V

Comparative performance of the nanomaterials

Crane, R A., Scott, T B. (In Review). Vacuum annealing, a new method to improve the reactivity of nanoscale zerovalent iron particles. J. Haz. Mat.


Significantly improved reactivity despite a 75% decrease in nanoparticle surface area

Option 2: Addition of a noble (cathodic) metal to improve galvanic properties



Comparative performance of the nanomaterials

Dickinson, M., Scott, T. B., Crane, R,A., Riba, O., Barnes, R.J., Hughes, G., (2009). The effects of vacuum annealing on the structure and surface chemistry of iron nickel nanoparticles. Journal of Nanoparticle Research. 12(6), 2081-2092.

Eh manipulation: 64.5 mV m-2 (nano-FeNi) 46.1 mV m-2 (nano-Fe0)

200 miles

50 miles

5000 L batch sorption experiments – is nano-Fe0 a viable ex-situ technology?


Implications for nanoparticle manufacture, storage and application

Nanoscale iron is highly effective for the rapid removal of uranium from groundwater despite the high carbonate concentrations.

For the removal of uranium from oxygenated (vadose zone) groundwater either “reactive” nano-iron is required or a secondary method to prevent DO ingress (geotextile, betonite, etc.)

Vacuum heat treatments and alloying of a noble metal have both been demonstrated as effective methods to improve the reactivity of nanoscale iron



Advantages:

• Highly effective for a large range of organic and inorganic contaminants in laboratory test systems• Rapid, easy and versatile to deploy• Clean up is rapidly achieved• Limited environmental disruption• Lower cost than classic alternatives

Disadvantages (or areas for future research):

• Destroys organic contaminants BUT only immobilises heavy metals and radionuclides •Nano-Fe0 cannot be easily recovered• Nano-toxicology issues

Advantages and disadvantages of the in-situ deployment of Nano-Fe0


Why am I at UNSW? Solute transport experiments using the NCGRT centrifuge facility


Thank you for your time

Crane, R.A. and Scott, T.B. (2012). Nanoscale zero-valent iron: future prospects for an emerging water treatment technology. J. Haz. Mater. 211, 112-125.

Noubactep, C., Care, S. and Crane, R.A. (2012). Nanoscale metallic iron for environmental remediation: prospects and limitations. Water Air Soil Pollut. 223, 1363-1382.

Scott, T.B., Popescu, I.C., Crane, R.A. and Noubactep, C. (2011). Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants. J. Hazard. Mat. 186, 280-287.

Crane, R.A., Dickinson, M., Popescu, I.C. and Scott, T.B. (2011). Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water. Water. Res. 45, 2931-2942.

Crane R.A. and Noubactep, C. (2012): Elemental metals for environmental remediation: learning from hydrometallurgy. Fresenius Environ. Bull. 21, 1192-1196.

Scott, T. B., Dickinson, M., Crane, R., Riba, O., Hughes, G. and Allen, G. (2010). The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles. J. Nano. Res. 12, 2081-2092.

Dickinson, M., Scott, T. B., Crane, R., Riba, O., Barnes, R., Hughes, G. (2010). The effects of vacuum annealing on the structure and surface chemistry of iron:nickel alloy nanoparticles. J. Nano. Res. 12, 2081-2092.

Crane, R A., Scott, T B. (In Press) The removal of uranium onto nanoscale zero-valent iron particles in anoxic batch systems. J Haz.Mater.

Crane, R A., Scott, T B. (Submitted for publication) Vacuum annealing, a new method to improve the reactivity of nanoscale zerovalent iron particles. J. Haz. Mater.

nanoscale zero-valent iron: a new technology for groundwater remediation? richard crane school of...

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