Nanorust Used To Purify Water

eldavojohn writes "How do you remove arsenic from water? Well, a research team has discovered that adding and removing nanorust works well. From the article, 'The team added nanoscale iron oxide to contaminated water, where it clumped together with the arsenic. They then magnetized the nanoparticles with an electromagnet and pulled them out. "We only needed a surprisingly weak magnetic field," says Colvin. "In fact, we could pull then out with just a hand-held magnet, making this a very practical method.' Big news for developing nations that are plagued with non-potable drinking water."

Comments

Some potential, but there are better options

[Salvance]

This method sounds like it could eventually have some potential, but it's not like you'll be able to take water directly from the Ganges, add some nanorust, and have fresh sparkling drinking water. In developing nations, the key is ensuring factories and agriculture do not dump their waste into the drinking supply (one of the big problems in India), that the sewage and drinking systems are separated, and that modern filtration units are used. Implementing all of these would be far cheaper than having people boil their water, and would ensure that bacteria, lead, and other impurities are removed.

The article itself admits that nanorust is still too expensive to be used widely, while filtration units already exist that cheaply remove arsenic plus many other things cheaply. In the U.S., home filters (and even cheap Britas) remove 99% of all arsenic, along with similar levels of other chemicals and heavy metals ... so why spend tons of money making nanorust if something else already exists that is cheaper and just as effective?

Re:Some potential, but there are better options

[slughead]

In developing nations, the key is ensuring factories and agriculture do not dump their waste into the drinking supply (one of the big problems in India), that the sewage and drinking systems are separated, and that modern filtration units are used.

The main source of arsenic poisoning is and has always been from naturally-occurring sources in soil.

I remember when the international community paid millions of dollars to supply Bangladesh with wells to give them water. The problem was, the earth in that area is naturally rich in arsenic and it caused the single largest occurrence of arsenic poisoning in the history of man. Better than dying of thirst, I guess... or not.

Re:Some potential, but there are better options

[Salvance]

Arsenic is present naturally in the ground, but not nearly in the levels found in Bangladesh and India. All hypotheses that the well water pollution is a natural source have been discounted over the past 5-10 years, and all evidence (mostly gathered by British researchers) points to manmade arsenic sources (fertizer primirily) leaching into the ground water.

India and other countries have proposed massively expensive projects to contend with the disaster (which India still contends is not manmade, but that's because it's in their best interest to do so), but most of these do not address the issue that contaminated water is depositing arsenic into ground water stores and aquifers.

Re:Some potential, but there are better options

[reverseengineer]

Much of the arsenic contamination in South Asian water is of natural origin- a fact that a lot of well-meaning developmental organizations learned when they dug wells in Bangladesh. The options for water without arsenic in the region are getting it from rivers, which are becoming a much less attractive option as they are forced to support ever greater populations and industrialization, and from wells deep enough to get below arsenic-bearing sediments, which are much more expensive.

The problem with filtration is that it requires a level of centralized distribution that does not exist in many parts of the world. Either you do it from a central water treatment plant, which requires building an infrastructure of pipes and sewers, or you have to distribute filters directly to people. This makes those people dependent on their government (bad choice) or western aid agencies (really bad choice)for drinking water. The idea here is that a village could make these themselves.

I definitely agree, though, that acceptable waste disposal will become a necessity for clean water in developing nations, particularly as they become more developed. Stories of industrial waste dumped into rivers used for drinking and bathing, and of human waste trickling through open trenches down city streets sound primitive, sound foolish- until you note that the great cities of the West operated like that for centuries, and indeed the part about keeping agriculture and industrial waste out of drinking water is still an problem.

Re:Some potential, but there are better options

[bmo]

"All hypotheses that the well water pollution is a natural source have been discounted over the past 5-10 years,"

Wrong.

Unless you've got a URL that disputes what this one says:

http://www.bgs.ac.uk/arsenic/bangladesh/reports.ht m

"13.1.4 Source of the arsenic

There is no doubt that the source of the As is natural, i.e., derived from 'ordinary' sediments by natural geochemical processes. The quantity of As present in groundwater (and adsorbed by the sediments) is simply too large to be derived from a discrete pollution source. Also its distribution across Bangladesh and West Bengal and with depth does not tally with a pollution source. There is also no need to postulate exceptional sources such as a particular mineralised area in the upstream catchment, as some workers have done for neighbouring West Bengal (Acharyya et al., 1999), although of course such areas may exist. This is one of the lessons that needs to be learned from the Bangladesh arsenic problem.

There is more than enough arsenic in most sediments to give rise to an As problem given the appropriate geochemical conditions for release and mobilisation. If all of the arsenic in a sediment containing 1mg As kg^-1 sediment dissolves in the groundwater, then the arsenic concentration would be 6000 micrograms/L or more, way above all drinking water standards. Both the average world and typical Bangladesh sediments contain several times this amount of arsenic. In other words, Bangladesh sediments do not appear to contain an exceptional amount of arsenic /in total/ yet give rise to exceptionally large groundwater arsenic concentrations. The high solid/solution ratio in aquifers and the great toxicity of arsenic mean that the contamination of groundwaters is sensitive to an imperceptible shift in the speciation of arsenic. A change of only a few percent in the partitioning of arsenic between sediment and water is sufficient to give rise to a significant groundwater arsenic problem."

So unless you've got some sort of documentation that trumps the British Geological Survey, I suggest you take a course in "rocks for jocks" (geology 101) instead of spewing your uninformed twaddle here.

--
BMO

Wonderful

[Anonymous Coward]

but you might get even more results with picorust.

Ounce of prevention?

[Mateo_LeFou]

question one should be How Did the Arsenic Get In There?

Is this a normal geological property or result of pollution?

Re:Ounce of prevention?

[k31bang]

ummmm perhaps it was there naturally? From http://www.nrdc.org/water/drinking/qarsenic.asp:

"5. How does arsenic get into water supplies?

Most arsenic enters water supplies either from natural deposits in the earth or from industrial and agricultural pollution. Arsenic is a natural element of the earth's crust. It is used in industry and agriculture, and for other purposes. It also is a byproduct of copper smelting, mining and coal burning. U.S. industries release thousands of pounds of arsenic into the environment every year."

*sigh*

[Ant P.]

So what's wrong with calling it something like "microscopically fine rust powder", or something else that doesn't reek of marketing buzzwords?

Re:*sigh*

[MBC1977]

Two reasons I can think of off the top of my head: (1) microscopically fine rust powder sounds geeky to the average reader, while nanorust sounds cool, and (2) who wants to actually spout microscopically fine rust powder, when it can be shortened to nanorust?

Granted it does sound like a buzzword, be even as a geek, I'd hate to have to say all of that, when ironically enough, nanorust actually would make sense to me. (disclaimer, I am a both a double major in business admin (marketing concentration) and computer science), so I can see both sides of the arguement here.

One other thing to think of, as it just came to mind... to capture (meaning get them interested) a venture capitalist or even the future generation of scientists (meaning the children), you gotta make it sound simple now days. A lot of smart people are turned off if it sounds too technical, (one of the reasons I believe a lot of children who are good at math -- I'm using my daughter for instance, is great at math, but gets frustrated because of the technical terminology (she always who came up with these stinking terms), whereas if its broken down to sound simple, then they understand it better and can do the work without complaint.

I didn't mean to go on diatribe, but I think that is the problem with a lot of professionals (be it computer geek, business geek, etc.) If its made simple, people will get interested enough to continue. Kinda like hammering a nail with w sledgehammer, its overkill.

Regards,

MBC1977,
(US Marine, College Student, and Proud Parent!)

Re:nanoscale

[Anonymous Coward]

wiki: "Iron(III) oxide is often used in magnetic storage, for example in the magnetic layer of floppy disks"
I should have known that. . .

Re:A case of "nano" for its own sake...

[Dilpo]

Read the article next time, no where in it does it say it requires nanorust, its just simply more efficient. From the article itself "One kilogram of nanorust has the same surface area as a football field," says Colvin. "Basically, you can treat a whole lot more arsenic with less material."

Is Hawaii a third world?

[Anonymous Coward]

Arsenic occurs naturally in volcanic rocks in Hawaii. However arsenic compound was used by white man as a herbicide on sugar plantations. Now Hawaii has a 10x more arsenic than naturally occurring in rocks. In fact some of the new hosing developments have to remove topsoil to be within (Hawaii relaxed) EPA standards.

Arsenic is insoluble so it just stays in ground or gets washed away. That's why coral-reef fish and algae's are usually contaminated the most.

Re:A case of "nano" for its own sake...

[the eric conspiracy]

It's still not a particularly wonderful idea. The best way of handling this sort of process is use of a microporous material like zeolites, ion exchange resins and so on. You still get an extremely high specific surface area - zeolites typically have areas on the order of 50 m^2 / g, which is about 10x the area claimed for the nanorust. Ion exchange resins can get up to 500 m^2 per gm (100x the nanorust). These materials because of their size can be separated using physcal processes (less capital intensive) and regenerated for reuse. In some cases they can be used in flow through systems so separation is not needed.

The question becomes...

[camperdave]

Where are you going to get all the nano-cars needed to generate this rust?

Re:first world is no better

[Dr. Smeegee]

All too true. For years I had planned on making a couple of "bug-out bags" for my spouse and I to keep in our cars and one for the house. The bags would contain light sleeping bags, batteries, crank lights and radios, "Iron Rations" several rolls of quarters, some spending cash, bottle of bleach, "dog antibiotics", phone numbers of all and sundry and brace of water purification tablets and hiker-style filtration systems. When the planes hit the towers I was forcibly reminded and resolved to gather the needed items ... and again when Katrina hit ... and I have about half of it. :-/

I live in a flood zone (my house was in up to the second story in 1937), and yet without the terror looming over on me, the sensible, simple preparations keep getting pushed to the back of the burner.

I paid $6.00 for breakfast at Hardees this morning. I could have bought almost a weeks worth of water purification tablets for that.