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Biopolymer-reinforced synthetic granular nanocomposites for affordable point-of-use water purification
Edited by Eric Hoek, University of California, Los Angeles, CA and accepted by the Editorial Board April 4, 2013 (received for review November 21, 2012)

Abstract
Creation of affordable materials for constant release of silver ions in water is one of the most promising ways to provide microbially safe drinking water for all. Combining the capacity of diverse nanocomposites to scavenge toxic species such as arsenic, lead, and other contaminants along with the above capability can result in affordable, all-inclusive drinking water purifiers that can function without electricity. The critical problem in achieving this is the synthesis of stable materials that can release silver ions continuously in the presence of complex species usually present in drinking water that deposit and cause scaling on nanomaterial surfaces. Here we show that such constant release materials can be synthesized in a simple and effective fashion in water itself without the use of electrical power. The nanocomposite exhibits river sand-like properties, such as higher shear strength in loose and wet forms. These materials have been used to develop an affordable water purifier to deliver clean drinking water at US $2.5/y per family. The ability to prepare nanostructured compositions at near ambient temperature has wide relevance for adsorption-based water purification.
Footnotes
↵1M.U.S., S.A., and S.M.M. contributed equally to this work.
- ↵2To whom correspondence should be addressed. E-mail: pradeep{at}iitm.ac.in.
Author contributions: M.U.S., A.C., A., and T.P. designed research; M.U.S., S.A., S.M.M., A.C., A., A.A.K., and K.C. performed research; M.U.S., S.A., A., and T.P. analyzed data; and M.U.S., S.A., A.C., A., and T.P. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. E.H. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1220222110/-/DCSupplemental.