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Science Technology

Cleaning the Environment with Iron Nanoparticles 41

Posted by michael from the clean-as-a-rusty-whistle dept.
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."
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Cleaning the Environment with Iron Nanoparticles More

Cleaning the Environment with Iron Nanoparticles

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  • Why doesn't this already occur? (Score:3, Interesting)

    by El ( 94934 ) on Friday September 05, 2003 @03:21PM (#6882562)
    Isn't there already lots of iron at these sites? Is the problem that we're not grinding it up finely first?
    • Surface area. Chunks of iron have less surface area than this nanoscale stuff. The story does mention that many companies already use a coarser form of this to help purify the wastes.

    • Re:Why doesn't this already occur? (Score:5, Informative)

      by fireduck ( 197000 ) on Friday September 05, 2003 @04:19PM (#6883135)
      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 [ogi.edu] has some diagrams of chemical pathways. Also try googling "zero valent iron".
  • There's no mention in the article of a downside. These things *always* have a downside. Anyone know what it is?

    Matthew

    • There's no mention in the article of a downside. These things *always* have a downside. Anyone know what it is?

      That's a good question. I don't know the answer, but maybe the catch is in finding a good way to grind up enough iron. I figure that it would take a whole lot of it to cover up the mistakes that people have made. Iron is a natural resource like trees. Trees take a long time to grow back. If we aren't careful with our iron management, then how will we gather up all this rust for new products?

      • Iron is one of the most common elements on the planet. There are *enourmous* resources of it - especially in north west Australia.

        The downside is, it takes energy to process and AFAIK results in in pollutants.

    • A simple chemical downside. (Score:4, Informative)

      by Bahumat ( 213955 ) on Friday September 05, 2003 @06:48PM (#6884333) Homepage Journal
      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.)

    • Everything is turned into a rust colour?

    • Iron is quite natural, however treatment with iron could make the soil slightly acidic.

      That and maybe the amount of base chemicals to create the dispersion and a possible neutralisation
      afterwards are the only things I can think of.

  • $5 per m^2 (Score:3, Funny)

    by pbox ( 146337 ) on Friday September 05, 2003 @03:37PM (#6882708) Homepage Journal
    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.
    • I didn't RTFA, but I would assume that when somebody refers to a land area in m^2, they're probably trying to say "of average depth".

      As in, "for the average depth of garbage at your average landfill, it will cost $5 per m^2, all the way down to the bottom"
      • You are probably right, however I do, regretfully, recall that the dump inext to the highway in north Palm Beach County, FL, where the average depth of the landfill was about 200-300 yards. I however seriously doubt that iron spread on top of that landfill would reach to bottom of it in the sunnier side of a thousand years. Maybe they meant to say for each layer (that should be about 2-3 yards). So it is still cheap if $5 takes care of 2-3 m^3...
    • They use injection wells. The nanoparticles then get carried from the injection site by groundwater. The method relies on the fact that the contaminants are generally soluble in water, and so the nanoparticles should get carried to wherever the contaminants are. They suggest one well and 11.2 kilograms of iron will treat 100 m^2. But they need to use a lot more iron then to just reduce the contaminants, as the soil naturally has plenty of reducible compounds. Presumably there is more or less a constan

  • Nanoscale titania works too. (Score:3, Informative)

    by auferstehung ( 150494 ) <tod.und.auferstehung bei gmail.com> on Friday September 05, 2003 @04:03PM (#6882964)

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

    See this Google search [google.com] and this page [unsw.edu.au]

  • Iron can be toxic (Score:2, Interesting)

    by kelleher ( 29528 )
    Iron Poisoning [calpoison.org] is one of the most frequent causes of poisoning death in children.

    • Re:Iron can be toxic (Score:4, Informative)

      by shamino0 ( 551710 ) on Friday September 05, 2003 @04:35PM (#6883282) Journal
      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 (Score:2, Informative)

        by dnahelix ( 598670 )
        ...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
        • ...and what if it gets into the water and a lake full of fish ingest all that iron?

          this will likely not happen. as someone who studies the transport of nano-sized particles in porous media, i can tell you the iron isn't going to migrate too far. (i research virus / bacteria filtration in subsurface environments.)

          the particles begin with a 0 net charge on them. however, they are quickly going to oxidize, likely to Fe(OH)2. This compound is itself ionizable depending on the solution pH (too early for
    • This is certainly true of the chewable children's vitamins with iron that are often in cartoon shapes with various colors and fruit flavors.
      More specifically than just iron poisoning, Flintstones Chewable Vitamins [amazon.com] are one of, if not the most common, causes of poisining in children.

  • Comment removed (Score:3, Informative)

    by account_deleted ( 4530225 ) on Friday September 05, 2003 @06:47PM (#6884326)
    Comment removed based on user account deletion

  • Is anyone else thinking thermite? (Score:1, Funny)

    by Anonymous Coward
    OK, so all we gotta do is take our nanoscale iron, let it rust into nanoscale rust.

    Mix in a percentage of nanoscale aluminium.

    Light a nanoscale match and WHOA!!! The quickest burning 7000 degree thermite I can think of.

    mmmmm..... thermite.....

  • High risk of heat and hydrogen (Score:3, Insightful)

    by G4from128k ( 686170 ) on Sunday September 07, 2003 @08:13AM (#6892365)
    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 [thermacare.com] 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.

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