Groundwater PollutionGroundwater Pollution

NanotechnologyNanotechnology

Nanotechnology involves the manipulation and understanding of

matter at the molecular or atomic level. . Due to the small size of

the particles, they exhibit very unique properties and behaviors

when compared to lager scale particles of the same material.

Advantages of Nanoscale Iron Particles (NIP)

Injectable directly into contaminated areas

Nontoxic (compared to other nanomaterials, including

bimetallics)

High surface area

Well defined structure

Highly reactive-rapid degradation

Low NIP/contaminant ratios requirement

Both in-situ and ex-situ

Treatment is governed by iron corrosion reactions, lowers redox

potential, generates hydrogen

Friendly to subsurface biomass

Chlorinated contaminant degradation is followed by the following

mechanisms:

Fe(0) → Fe2+ + 2e-

2H2O → 2H+ + 2OH-

2H+ + 2e- → H2 (g)

R-Cl + H+ + 2e- → R-H + Cl-

C2HCl3 + 3H+ + 6e- → C2H4 + 3Cl-

NIP possess high reactivity with different contaminants (aqueous

and soil systems). Increased NIP concentration increases the

reactivity.

Importance of Field DeliveryImportance of Field Delivery

Batch tests with sand initially spiked with DNT=740 mg/Kg

High Hamaker constant-i.e. attractive van der Waals forces

Chemical bonding

Hydrophobicity

Magnetic attraction (Fe0)

Settling due to their higher density

Attachment (sorption) of particles to soil surfaces

The study investigated the reactivity during transport using

horizontal column. We injected NIP slurry from one end and

collected the effluent from the other end.

The results show that lactate enhances the transport of NIP

through the soil, but optimization of lactate and NIP

concentrations is essential in order to ensure both adequate

transport and reactivity of NIP.

T=0 min.

T=4 min.

T=8 min

T=13 min.

Reactivity During TransportReactivity During Transport

Test Conditions

1 g/L 1 g/L with Lactate 4 g/L 4 g/L with Lactate

PC

P M

as

s (

%)

0

20

40

60

80

% Remanied in Soil% Removed in Effluent% Degraded

Conclusions & RecommendationsConclusions & Recommendations

Lactate modification can minimize settlement and aggregation

of NIP

Reactivity of NIP reduces with lactate-modification, but

increases with time with or without lactate modification

Lactate modification is effective for maintaining the

permeability (particularly at higher NIP dosages) and better

transport of NIP in field sand

Lactate and NIP dosages and flow velocity should be optimized

for effective delivery as well as reactivity for specific

contaminant and soil type

Mathematical modeling and field pilot testing is in progress

Overall, our research has shown that nanotechnology has

emerged as a viable option to reduce the contaminant levels in

groundwater below the target risk-based levels.

Global Solutions

Prevent groundwater contamination

Reduce nonpoint runoff

Reuse treated wastewater for irrigation

Practice four R's of resource use (refuse, reduce, recycle, reuse)

Reduce resource waste and air pollution

Reduce poverty and high birth rates

Composition: α-Fe Core and Magnetite ShellAvg. Particle Size : 70 nmS.S.A. : 30Content m2/gSulfur : 5,000 mg/kg

70nm

Fe3O4

Fe070nm

Fe3O4

Fe070nm

Fe3O4

Fe0

NIP with 10%

Aluminum Lactate

Bare NIP

Initial After pore volume # 12

Overall reactivity shows that 1g/L aluminum lactate enhanced the

distribution of NIP, which resulted in the highest degradation of

PCP. This shows that NIP can be effectively used to

decontaminate polluted groundwater.

Decontamination of Polluted Groundwater Using Nanotechnology Kenneth Darko-Kagya

University of Illinois at Chicago (UIC)Department of Civil and Materials Engineering

Performance of NIP for in-situ remediation is highly dependant

upon its delivery to the point of need in the subsurface. Delivery

of NIP can be done by injecting the slurry through drilled

boreholes. The study investigated the transport of NIP using glass

columns mounted vertically. The study found out that most of the

bare NIP particles accumulated at the top of the soil after several

flushing of electrolyte under pressure. The limited transport of

the bare NIP was due to aggregation of the particles, which is a

result of the following factors;

World population has increased 3x

Global water withdrawal has increased 7x

Per capita water withdrawal has increased 4x

Half of the world’s 500 rivers are heavily polluted

Up to 80% of Europe, Russia, Middle East and North America

depend on Groundwater.

About 45% of the available fresh water is in a form of

groundwater

Groundwater pollution is on the rise due to increase use of

pesticides, fertilizers, synthetic organic compounds, solid

waste disposal site.

Pollution can be due to point and non-point sources

About one-sixth of the world’s people don’t have easy access

to safe water

80% of Diseases in developing countries are water related

Water pollution gets people sick and can kill

Chemistry

Despite the ability of the lactate to enhance the dispersivity of

the particles. Its reactivity was reduced due to the surface

coating. The difference in reactivity between NIP and LM-NIP was

large initially but diminished after seven days. This can be due to

the fact that aluminum lactate was protecting the NIP from easily

getting oxidized or passivated. This indicates that aluminum

lactate-modified NIP has a strong potential for remediation of

soils contaminated with DNT in addition to enhanced transport in

soils.