Cleaning the Environment with Iron Nanoparticles

Roland Piquepaille writes "In "Nanoscale Iron Could Help Cleanse the Environment," the National Science Foundation (NSF) reports that "nanoscale" powder made from iron could be used to clean contaminated soil and water. "Iron's cleansing power stems from the simple fact that it rusts. When metallic iron oxidizes in the presence of contaminants, these organic molecules get caught up in the reactions and broken down into simple carbon compounds that are far less toxic." Using this technology, cleaning landfills or industrial sites would cost about $5 per square meter. More details are available in this summary, including other links and a diagram showing how the method works."

Comments

Why doesn't this already occur?

[El]

Isn't there already lots of iron at these sites? Is the problem that we're not grinding it up finely first?

Re:Why doesn't this already occur?

[fireduck]

the size is part of the issue (smaller particles have more surface area). the more important point is that iron in the evironment is already in an oxidized state, e.g., Fe(OH)2. And it is the oxidation/reduction reaction that is driving the detoxification of the compounds. Specifically, Fe0 goes to Fe2+ or Fe3+, giving up 2 electrons which then are used to reduce the compound. (reduction also has the benefit that it usually makes the compound more amenable for microorganisms to chew up naturally).

This site has some diagrams of chemical pathways. Also try googling "zero valent iron".

Re:While this is a step in the right direction...

[El]

Iron oxide occurs naturally. People have been cooking with iron frying pans for years, and studies show it's actually good for you in trace amounts. Eating an entire frying pan in one sitting, however, is most likely bad for you.

$5 per m^2

[pbox]

That comes out to $INF per m^3. Too bad...

What kind of whacky measurement is this? Waste is (last time I checked) three (!!!) dimensional.

Nanoscale titania works too.

[auferstehung]

Nanoscale titania (esp. anatase) is also useful for pollution cleanup. Some researchers are even combining it with nanoscale iron oxed.

See this Google search and this page

Iron can be toxic

[kelleher]

Iron Poisoning is one of the most frequent causes of poisoning death in children.

Re:Iron can be toxic

[shamino0]

Iron Poisoning is one of the most frequent causes of poisoning death in children.

That article is talking about children overdosing on iron pills. You'd have to eat a lot of dirt to get that kind of iron into your system from the ground.

Re:Iron can be toxic

[dnahelix]

...and what if it gets into the water and a lake full of fish ingest all that iron? I think the point is valid and the original post should NOT be modded Troll. That is too harsh. The link that is provided does go into detail about how iron can be poisonous.

"What happens in an iron overdose?
When someone takes too much iron, the first effect is irritation and ulceration of the stomach lining. This results in nausea, abdominal pain and vomiting as early as 20 minutes after the ingestion. This can be followed by an apparent recovery, which is very deceptive because a few hours later the person can go into pro-found shock with a severe blood chemistry imbalance. When too much iron gets into the bloodstream, it goes to all the organs and can damage the stomach, liver, kidneys, lungs, blood vessels and brain. "

The completely valid question is could this happen to animals if a lot of nanoscale particles of iron were released into the ecosystem?

Will not work.

[DigiShaman]

If you spray water into a fine mist in sub-zero climate, then you will get instant snow. But if you spray an ultra fine powder of iron in a humid inviroment, chances are great that it will be rust by the time it lands on the ground. In fact, all you have to do is look at your own blood. It turns red the moment the hemogobin reacts with oxygen...which is made up if trace amounts of iron.

Re:Will not work.

[bitMonster]

LTFD (Look at The F* Diagram). They are injecting it into the ground using special wells.

A simple chemical downside.

[Bahumat]

Rusting iron consumes free oxygen. When used in water sources, this can be a very Bad Thing for most closed-system watersheds.

Powdered iron has been suggested as a means of controlling greenhouse buildup by scattering hundreds of tons of it across the surface of the pacific ocean; it creates dramatic blooms of algae in the water that suck up carbon dioxide and other pollutants.

The problem to this, of course, is that the ocean is a closed-system as well, albeit a far larger one. The iron rusts, consumes oxygen, leaving fish in oxygen-deprived waters and with little place else to go. (Fish aren't immune to pressure, quite the opposite, so no, going down isn't much of an option.)

High risk of heat and hydrogen

[G4from128k]

I noticed a product called ThermaCare that uses an air-iron exothermic reaction to create a single-use heating pad. The description of the ingredients at ThermaCare's FAQ suggests some interesting and bad consequences of iron oxidation reactions. These include:
- the potential for generating uncontrolled levels of heat depending on the mix of iron, air, and accelerants.
- the potential for generating explosive hydrogen gas (in forming iron oxide from iron and water, hydrogen is left over).

Nanoscale iron reactions may well detoxify many pollutants. But high heat generation could volatilize solvents and explosions in and around contaminated soil don't seem wise either. I assume that some test samples would ensure that the soil was not too aerobic so that heat and hydrogen generation would be sufficiently gradual to forestall a dangerous reaction, but testing will always be imperfect.