(Beyond Pesticides, January 14, 2008) Researchers at the Indian Institute of Technology (IIT) Madras have developed nanoparticles that can remove organochlorine pesticides from drinking water. These chemicals are quite persistent in the environment and difficult to remove from water. Notorious organochlorines include DDT, endosulfan, HCH (hexacholorcyclohexane) and aldrin, all of which have known health and/or environmental hazards. Many of these chemical pesticides are used heavily in agriculture and taint India’s water. Though no comprehensive national survey has been done, isolated studies show contamination of groundwater and river systems that cannot be removed by standard water filters. “Even though some of these pesticides have been banned, they are very much present in the environment. For instance, endosulfan has an environmental lifetime of 100 years,” said Thalappil Pradeep, professor of chemistry at IIT Madras. He leads the research that has shown that nanoparticles, mostly from gold, silver, copper and several oxides, are effective at removing endosulfan even at very low concentration. “Efficient chemistry at low concentration is important so that even if one molecule of the pesticide passes by, it gets removed by the nanoparticle,” said Pradeep.
He holds a US and an Indian patent and has licensed part of the technology to Eureka Forbes, Ltd., makers of water purifiers and vacuum cleaners. In June 2007 Eureka released water filter that used nanosilver technology. “We wanted to productize and demonstrate our technology and create some excitement. So we took up initial industrial development at IIT,” said Pradeep. But any technology of this kind, he believes, needs to go the “real sufferers in rural areas”. His current nanoparticles are effective on four most common organochlorine pesticides (OPs) — DDT, endosulfan, malathion, and chlorpyrifos.
Eureka plans to make this technology available to rural populations in the future but the high cost of manufacturing could hold this effort back for some time. “We intend to take this up as a no-loss, no-profit venture but that will have to wait until production goes up (and cost comes down),” said Abhay Kumar, general manager of water technologies division at Eureka in Bangalore. A community water purifier prototype, using nanotechnology filter, is under construction. It is scheduled to be installed in Kasargod district, an area in Kerala affected by endosulfan, by March. “This effort has to multiply, through all possible channels — industry, non-governmental organization and most importantly, government machinery,” said Pradeep, whose interaction with the Central water resources ministry turned out to be a one-way affair. Under the US Clean Water Act of 1972, the extent of contaminants in a glass of water is decreasing, but the number of contaminants entering potable water is increasing, said Pradeep. While the technology to remove contaminants from water is improving, the agriculture industry continues to douse their crops with more and more chemical pesticides, which can end up in water supplies.
Experts believe that eventually nanomaterials could be used to purify not only water but also ambient air indoors. “Many of these organics are extremely stable in the environment. Hence, chemistry of novel materials is the need,” said Pradeep. His group has also developed a pesticide test kit, slated to enter the market this year. One of the early proponents of nanotechnology for water purification when he came to IIT Madras 14 years ago from Purdue University in Indiana, US, Pradeep now has a slew of new nanomaterials that could free water from heavy metals like lead and mercury and other OPs.
Nanotechnology has received considerable attention, but optimism in the new developments is tempered by caution about the unknown effects of manipulating particles at such a small scale. With more consumer products containing nanomaterials hitting the shelves every day, a broad international coalition of 40 consumer, public health, environmental, and labor organizations released Principles for the Oversight of Nanotechnologies and Nanomaterials in July 2007. The report calls for strong, comprehensive oversight of the new technology and its products, which is built on a precautionary foundation to prevent risks to the public, workers and the environment. In September 2007, EPA determined that devices that emit ions for pesticidal purposes will be regulated as pesticides. Washing machines that contain electrodes that emit silver, copper or zinc ions would likely be subject to this oversight.
Source: Live Mint