Nanoscale iron particles are sub-micrometer particles of

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

metal. They are highly reactive because of their large surface area. In the presence of oxygen and water, they rapidly

oxidize Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...

to form free iron ions. They are widely used in medical and laboratory applications and have also been studied for remediation of industrial sites contaminated with chlorinated organic compounds.

Synthesis

Iron nanoparticles can be synthesized by the reduction of Fe(II) or Fe(III) salt with sodium borohydride in an aqueous medium.

Reactivity

When exposed to oxygen and water, iron oxidizes. This

redox Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...

process can occur under either

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...

ic or neutral/

basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

conditions: :2 Fe⁰(s) + 4 H⁺(aq) + O₂(aq) → 2 Fe²⁺(aq) + 2 H₂O(l) : Fe⁰(s) + 2 H₂O (aq) → Fe²⁺(aq) + H₂(g) + 2 OH⁻(aq)

Research

Research has shown that nanoscale iron particles can be effectively used to treat several forms of ground contamination, including grounds contaminated by

polychlorinated biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act of 1976, Toxic Substances Contro ...

s (PCBs), chlorinated organic solvents, and organochlorine pesticides. Nanoscale iron particle are easily transportable through ground water, allowing for

in situ ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...

treatment. Additionally, the nanoparticle-water slurry can be injected into the contaminated area and stay there for long periods of time. These factors combine to make this method cheaper than the most currently used alternative. Researchers have found that although metallic iron nanoparticles remediate contaminants well, they tend to agglomerate on the soil surfaces. In response,

carbon nanoparticles Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid ...

and water-soluble

polyelectrolyte Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are ...

s have been used as supports to the metallic iron nanoparticles. The

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, ...

contaminants adsorb to these supports, improving permeability in sand and soil. In field tests have generally confirmed lab findings. However, research is still ongoing and nanoscale iron particles are not yet commonly used for treating ground contamination.

References

2.http://www.chalcogen.infim.ro/1771_Yuvakkaur.pdf

External links

National Nanotechnology Initiative

Largescale production and applications of zero-valent iron nanoparticles (nZVI)
Nanoparticles by composition Environmental science Pollution control technologies Iron {{nano-tech-stub

Synthesis

Reactivity

Research

See also

References

External links