Application of NZVI - Final

8/12/2019 Application of NZVI - Final

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APPLICATION OF NANOSCALE ZERO

VALENT IRON (nZVI) FOR GROUNDWATER

REMEDIATION

Presented by

Misnagama Gamage Aruna JayamanjulaS194373

Master of Petroleum Engineering


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OUTLINE OF PRESENTATION

1. Introduction

2. Implementation of Field Application of nZVI

3. Field Application of nZVI

4. Costs

5. Conclusion


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1. INTRODUCTION

1.1 Current Situation of Contaminant Remediation

In Europe polluted sites to be remediate - 20,000 + Identified potentially contaminated

sites 350,000 ----- European Environment Agency. In USApolluted sites to be remediate 235,000 to 355,000 ----- U.S. EPA 2005.

It is expected that ex situ remediation techniques will be

phased out over the coming decade. (Karn et al. 2009).

Passive in-situ treatment method using granularzero valent iron (ZVI)

Metallic iron very effective in transforming a wide

variety of common contaminants (chlorinated

methanes, brominated methanes, trihalomethanes,

chlorinated ethenes, chlorinates benzenes, other

polychlorinated hydrocarbon pesticides, and dyes)into less toxic compounds.

a) Pump and Treat Method An ex-situ treatment technology.

The predominant technology for addressing

groundwater contamination until 1992 (Karn et al.

2009; U.S. EPA 2005). Operates for about 18 years as very expensive and

slow

b) Permeable Reactive Barrier


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ZVI reduces inorganic anions also such as nitrate reduces to ammonia, perchlorate (plus

chlorate or chlorite) reduces to chloride, selenate, arsenate, arsenite, and chromate.

ZVI also efficient in removing dissolved metals from solution.

The major drawback: PRBs can only address contaminant plumes that flow through the

barrier and hence they do not contribute to the active removal of the source.This has a

direct impact on the duration of the remediation and the availability of the land for reuse.

1. INTRODUCTION (contd.)

c) Nanoscale Zero Valent Iron (nZVI)

Nanoscale iron particles arebased on the large specific

surface areasignificantly more reactive than conventional

ZVI and are to some extent able to migrate below ground,

which allows active remediation of the contaminated plume

and the source. These beneficial properties led to a rapid

increase of site remediationwith nZVI. Other types of nanoparticles have also been tested - zeolites,

calcium oxide, iron oxides, and (bi)metallic iron.

nZVI (nanoscale zero valent iron) is the most commonly used

nanomaterial for soil and groundwater remediation at the

present.


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Principle


Zero-valent iron reacts chemically as reductive agent (it is

oxidized = get rusty)

2eFeFe 2o

CHC are reduces with overall reaction

3ClHC5Fe5HHClC5Fe62

2

32

o

It was confirmed in laboratory that > 70 compounds can be reduced (Zhang, 2003):

o Chlorinated Hydrocarbons (CHC): TCE, PCE, DDT, PCB, PCM, PCP, lindane,

oHeavy Metals: Pb, Hg, Ni, Cd, Cr, As, U, etc.

o others:nitrates, TNT


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1.2 NZVI Modifications & Types used for Soil and Groundwater Remediation

Sources: Muller et al. (2010), Quinn et al. (2005), EPA

Abbrev. Description Characteristics

ZVI Zero valent iron MicroscaleNZVI Nanoscale zero valent iron (surface modified, e.g.,

with starch, carboxymethylene cellulose, polyacrylic

acid, cellulose, inhicor-T, Tween 60 or 80)Surface modification aims to increase

mobility in the ground

BNZVI Bimetallic NZVI(NZVI combined with a metal catalyst

such as Ni, Pd, Pt, Cu, Ag) BNZVI has high reaction rate than NZVI butconsequently a shorter lifetimec-NZVI NZVI on carbon support (NZVI combined with active

carbon platelets of 50200 nm diameter) c-NZVI may be used to enhance the NZVIdistribution in contaminated aquifers (nofield tests carried out yet)

ENZVI Emulsified NZVI [NZVI core in water coated by food-

grade surfactants and biodegradable vegetable oil

which form an oilliquid membrane (about 15 m in

diameter)]

ENZVI was designed for the in situ treatment

of dense non-aqueous phase liquids

(DNAPLs). Due to the hydrophobic coating,

ENZVI can mix with organic contaminants.Fe(B)

Amorphous type of NZVI made from borohydridereduction of dissolved Fe(III)

NANOFER NZVI produced from nanosized ferrihydrite by the

Czech company NANOIRONRNIP Reactive nanoscale iron particlea crystalline type

of nano-iron made by gas phase reduction of

FeOOHproduced by TODA Inc. Japan.


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1.3 Pilot Tests in Europe Comparison Table

Source: Muller et al. (2012)



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2. IMPLEMENTATION OF FIELD APPLICATION OF nZVI

Laboratory Experiments feasibility approval

Batch experiments: groundwater + soil + nZVI concentration

Concentration dependency (efficient concentration) in g/L

Kinetic (reaction rate)

Comparison of different products

Regulatory Approval

Subjected to decision of local authority

Field Pilot Study

Usually 100-500kg of nZVI

Before a full-scale application of nZVI, a precise site investigation and pilot tests are

needed, to evaluate the site hydrogeology as well as the geochemistry.

The hydrogeology influences the transportabilityof the particles.

The geochemistry indicates potential substances that nZVI could react with other thanthe target compounds and thus determines the lifetime of the reactive particles.

Pilot tests are conducted to provide information on the amount of nZVI needed and

possible unanticipated challenges.

Full Scale Remediation


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3. FIELD APPLICATION OF nZVI

3.1 Site Condition

Site Location: Kara Trutnov in Czech Republic

Source: Fur processing site

Contaminant: Chlorinated ethenes (PCE, TCE, DCE, VC) and chromium (Cr6+)

Previous treatment: pump & treat, venting, vapour deposition, potassium permanganate -

In Situ Chemical Oxidation (ISCO)

Nano-material applied : NanoFer 25S Average particle size : 50nm

Narrow particle size distribution : 20-100nm

Average surface area : 20-25m2/g

Surface Modification : by combining biodegradable organic

and inorganic stabilizers.

Due to the narrow size distribution of nanoparticles and

sophisticated stabilization process, the product exhibits a high

reactivity with a large scale of pollutants and very low degree of

agglomeration, which implies for excellent migration and

sedimentation properties.

3.2 Specification and Characteristics of the Nano-material

TEM images of nanoparticles of NANOFER

25S, stabilized by combination of organic

and inorganic phases


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Characteristics of Nanofer 25S

XRD pattern of zero-valent nanoparticles of -Fe

with weight content of 90 % and average

particle size of 50 nm (derived from the Scherrerformula); magnetite - Fe3O4(m) as a by-product

Primarily produced (non-stabilized) Fe(0) nanoparticles with recordly small size and

narrow size distribution by view of scanning electron microscopy (SEM).

BET adsorption-desorption isotherms of Fe(0)

nanoparticles with surface area of 25 m2/g.

X-ray diffraction (XRD) used to investigate the material

structure of iron nanoparticles. ZVI presence indicate the

narrow peaks at 52o, 78o& 100oand magnetite Fe3O4(m) as

a by product. Specific surface area of the nanoparticle was determined

with the classic BET method (the BrunauerEmmettTeller

isotherm).

3. FIELD APPLICATION OF nZVI (contd.)


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3.3 Laboratory Experiment

Samples: 100 samples using real ground water with the

addition of soil from the site

Three different test conditions:o Soil + 0 g/L nZVI

o Soil + Lactate + 0 g/L nZVI

o Soil + 1 g/L nZVI

Tests: Batch tests

Results of Laboratory Experiment for PCE and Cr(VI)



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3.4 Pilot Test

Applied 200kg of NANOFER 25S.

Target dosing concentration of 2g/L.

Pump into 2 injection wells ME-6 and ME-24.



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Chemical composition of ground water - well ME-24

parameter unit

September

8th

September

20th October 22nd

October 31st

pH - 6,94 8,58 7,98 7,87

Total chromium (Cr tot.) mg/L 42,5


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06/2012

02/2012

3.6 Full Scale Remediation First Injection: Winter/2011

o 2000kg of Nanofer was

injected using 12 injection

wells.

Second Injection: Spring/2012

o 1800kg of Nanofer was

injected.



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4. COSTS: nZVI COMPARING TO OTHER PRODUCTS

Application cost is important

Lower amount of nZVI is needed Better mobility of nanoparticles = less injection wells

Faster application

Higher efficiency

All parameters affect

remediation cost

Absolute cost of material

($/kg) is not representative


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Higher price of nanoiron is compensated by properties that are missing in other materials

and methods.

However, the site characteristics determine the optimum method.

Perspectives: For contaminants types where high reactivity is needed (for PCE)

For sites where presence of toxic intermediated (VC) is hazardous.

In the proximity of water sources since iron does not harm the quality of water

To enhance remediation processes started by other technologies.

In Europe, only regular nZVI is applied because of concerns regarding the toxicity of the

catalysts in BNZVI. The competitiveness of nZVI for source treatment is in general very limited in comparison

with ISCO (in situ chemical oxidation).

5. CONCLUSION


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REFERENCES

1) Muller N.C., Braun J, Bruns J, Cernik M, Rissing P, Rickerby D, Nowack B (2012), Application of

nanoscale zero valent iron (NZVI) for groundwater remediation in Europe, Environ Sci Pollut

Res (2012) 19:550558. (Main Article)

2) Slunsk J (2013), Utilization of Zero-Valent Iron nanoparticles (nZVI) for in-situ groundwater

remediation including recent field scale application and remediation experience,

Applications of Nanotechnology for Safe and Sustainable Environmental Remediation

technical session, USA.

3) Zhang W (2003), Nanoscale iron particles for environmental remediation: an overview, J

Nanopart Res 5:323-332.4) http://www.nanoiron.cz/en/characteristics-of-iron-nanoparticles
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Application of NZVI - Final