From: Robina Suwol
Date: 28 Aug 2006
Time: 17:36:45
Remote Name: 69.149.54.226
Using Gold to Trap Pesticides in Water
Karthik Subramanian
IIT-M Scientists Patent Technology To Use Nanoparticles To Trap Pesticide Residue
a.. Gold and silver nanoparticles can adsorb pesticides
a.. Endosulfan, malathion, chlorpyrifos can be filtered
a.. Scientists see great possibilities for application of technology
CHENNAI: The most precious role yet for gold and silver could be in the field of water purification.
Two scientists from the Indian Institute of Technology, Madras, T. Pradeep and A. Sreekumaran Nair, have patented technology to use gold and silver nanoparticles to filter endosulfan, malathion and chlorpyrifos pesticides from water. The technology exploits the ability of the nanoparticles to bind residual pesticides from flowing water through adsorption.
Eureka Forbes, manufacturers of the Aquaguard range of water filters, have acquired a licence to use the technology. It is set to roll out products featuring the technology soon. P.J. Reddy, Director of Aquamall Water Solutions Limited, a subsidiary of Eureka Forbes, said initially they would integrate the technology into their high-end products.
The scientists hope that the technology would address the growing concern over access to safe drinking water. In his paper on `Societal implications of nanoscience and nanotechnology in developing countries,' co-authored with IIT colleague Birgit R. Burgi and published in the journal Current Science, Dr. Pradeep notes, "Water purification systems equipped with nanomaterials and using new kinds of membrane technologies with variable pore sizes as filters could provide people in any area with safe drinking water."
In their lab experiments conducted during 2003 and 2004, Dr. Pradeep and his team of scientists at IIT discovered that gold particles of diameter 10 to 20 nanometres and silver particles of diameter 60 to 80 nanometres had the tendency to adsorb pesticides. They found out that the nanoparticle solutions changed colour while interacting with water that had residual pesticides.
There was one hitch though - they had no apparatus to observe results to the resolution of parts per billion (ppb). This was necessary because the Bureau of Indian Standards prescribed acceptable level of residual pesticide at 0.5 parts per billion (ppb).
The crucial test was possible at the internationally-certified Aqua Diagnostic Labs of Eureka Forbes in Bommasandra near Bangalore. Results from gas chromatography equipment with electron capture detector showed that the nanoparticles physically entrapped the pesticide residues. The presence of residual pesticides was below the accepted levels.
Dr. Pradeep said it would be possible to use the technology on a bigger scale than in home water purifiers. "If any village panchayat approaches us with a demand to fabricate a filter for the community we can even waive the royalty."