Posted on 02/03/2011 5:34:32 PM PST by neverdem
An iron-rich, porous material can remove arsenic from drinking water in under two hours, say Chinese scientists.
Arsenic is notoriously toxic, proving fatal to the majority of living organisms in high doses. Elevated levels of arsenic in groundwater in countries such as Bangladesh pose a serious threat to human health. But traditional methods to remove the arsenic struggle to eliminate the more dominant arsenic ion, arsenite.
Now, Kang Li and colleagues from Harbin Medical University have removed arsenite from water samples using ferrihydrite - a low cost, natural mineral found on the Earth's surface. Already known to absorb arsenic, its efficiency is usually hindered by its low surface area. The team overcame this by combining two layers of ferrihydrite, increasing its surface area and loading capacity. Arsenite was selectively removed from water, even in the presence of other anions with similar molecular structures. Removal of the arsenite from the surface of the ferrihydrite material was easily achieved by washing it with an alkali solultion. After a heat treatment, the mesoporous material could be reused up to ten times.
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Elevated levels of arsenic in drinking water pose a serious threat to human health
© UNITED NATIONS
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Li believes that the recycling aspect holds the greatest challenge for future practical applications for the material. 'If magnetic nanoparticles could be loaded in the channels of the two-line ferrihydrite, recycling would become even easier,' he says.
'The next step should be related to the investigation of the mechanism and efficiency of arsenic removal by nanocrystalline iron oxides depending on their structure and crystallinity,' says Radek Zboril, an expert in nanocrystalline iron oxides from Palacky University in the Czech Republic.
'The incorporation of arsenic into the structure of the in situ formed iron oxide nanoparticles seems to be a more promising way from the viewpoint of real applications.'
One-step synthesis of mesoporous two-line ferrihydrite for effective elimination of arsenic contaminants from natural water
Zhenzi Li, Tao Zhang and Kang Li, Dalton Trans., 2011
DOI: 10.1039/c0dt01138j
You do a great job commenting thoughtfully and often with great insight, so I appreciate the compliment.
I learned about hormesis from Art Robinson who was a student researcher with Linus Pauling. It was a long time ago, but they had a falling out over vitamin C (Robinson said the results disproved Pauling’s contention that C was a cure-all and often worsened some diseases).
Pauling’s other sin, like a lot of liberal gurus they have so many and never apologize, was that radiation or any insult to the body was always bad (linearly, i.e. the more the worse). This lead to our modern Greens, Communists, and EPA calling for “zero” levels of any toxin.
Clearly, this is unscientific as dose makes every poison and oxygen and water are toxic at the proper level. But, Robinson went further proving that hormesis exists and as regards radiation too little radiation causes cancer.
Robinson contends that Australian life guards have the lowest incident of skin cancer, but the highest of sun exposure. Look him up it is interesting stuff.
I might be confusing stories, but he worked in a lab where Pauling was working on showing how dangerous DDT was. They fed lab rats DDT and the control group a “healthy” diet, including Linus’ darling vitamin C. The DDT rats thrived, grew larger than normal and were trim and muscular while the rats on the “healthy” diet didn’t.
Pauling pulled the plug when his RAs started calling DDT, Vitamin DDT. He was a jerk and a liar.
You’d like Art Robinson. Search around for him. He and his children are a remarkable bunch - Christians, Scientists and great thinkers - naturally they’re conservatives. ;-]
Spread the word. There’s nothing like the truth, eh?
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