Steve, Are you aware of any methods to remove fluoride from city water?
Dan On Mon, Jul 19, 2010 at 10:40 PM, Norton, Steve <stephen.nor...@ngc.com> wrote: > This is interesting. A study has shown that silver nanoparticles completely > remove endosulfan, malathion and chlorpyrifos from water. The mechanism of > removal is adsorption followed by catalytic destruction. A household filter > that uses the technology to remove pesticides from water has been developed. > > - Steve N > > http://www.rsc.org/chemistryworld/News/2007/April/20040701.asp > > Pesticide filter debuts in India > > A domestic water filter that uses metal nanoparticles to remove dissolved > pesticide residues is about to enter the Indian market. Its developers at > the Indian Institute of Technology (IIT) in Chennai (formerly Madras) > believe it is the first product of its kind in the world to be > commercialised. > > Mumbai-based Eureka Forbes Limited, a company that sells water purification > systems, is collaborating with IIT and has tested the device in the field > for over six months. Jayachandra Reddy, a technical consultant to the > company, expects the first 1000 units to be sold door-to-door from late May. > > 'Our pesticide filter is an offshoot of basic research on the chemistry of > nanoparticles,' Thalappil Pradeep who led the team at IIT Chennai > told Chemistry World. He and his student Sreekumaran Nair discovered in 2003 > that halocarbons such as carbon tetrachloride (CCl4) completely break down > into metal halides and amorphous carbon upon reaction with gold and silver > nanoparticles1. > > Pradeep said this prompted them to extend their study to include > organochlorine and organophosphorous pesticides, whose presence in water is > posing a health risk in rural India. In research funded by the Department of > Science and Technology in New Delhi, his team found2,3 that gold and silver > nanoparticles loaded on alumina were indeed able to completely remove > endosulfan, malathion and chlorpyrifos - three pesticides that have been > found at elevated levels in Indian water supplies. > > Use and recycle > > The mechanism of removal is 'adsorption followed by catalytic destruction', > Pradeep explained. 'The chemistry occurs in a wide concentration range of > environmental significance.' He added that tests proved silver particles > from the filter are not released into the water. The IIT study found that > gold particles perform better in the case of endosulfan. However, for cost > reasons, the commercialised filters use only silver particles, which range > in size from 60 to 80 nanometres at a concentration (on their alumina > support) of 33 parts per million. > > 'Based on consumption patterns of a typical Indian household, the filter is > designed to have enough nanomaterials to provide 6000 litres of > pesticide-free water for one year,' Pradeep said. 'After that, the company > will recycle the filters to recover the silver.' > > Use of nanoparticles for environmental remediation is an emerging area of > research worldwide. Nanoscale iron powders had been shown to degrade other > pesticides, including DDT and lindane4, 'and there are reports about the use > of nanomaterials for removing arsenic, heavy metals and fluorides,' said > Pradeep. 'But ours is the first product to hit the market,' he said. -- The Silver List is a moderated forum for discussing Colloidal Silver. Rules and Instructions: http://www.silverlist.org Unsubscribe: <mailto:silver-list-requ...@eskimo.com?subject=unsubscribe> Archives: http://www.mail-archive.com/silver-list@eskimo.com/maillist.html Off-Topic discussions: <mailto:silver-off-topic-l...@eskimo.com> List Owner: Mike Devour <mailto:mdev...@eskimo.com>
