A Nano-Solution to Global Water Problem: Nanomembranes Could Filter Bacteria

[OKIsItJustMe]

http://www.buffalo.edu/news/12288

News Release

A Nano-Solution to Global Water Problem: Nanomembranes Could Filter Bacteria

Release Date: February 21, 2011

BUFFALO, N.Y. -- New nanomaterials research from the University at Buffalo could lead to new solutions for an age-old public health problem: how to separate bacteria from drinking water.

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Working with a special kind of polymer called a block copolymer, a UB research team has synthesized a new kind of nanomembrane containing pores about 55 nanometers in diameter -- large enough for water to slip through easily, but too small for bacteria.

The pore size is the largest anyone has achieved to date using block copolymers, which possess special properties that ensure pores will be evenly spaced, said Javid Rzayev, the UB chemist who led the study. The findings were published online on Jan. 31 in Nano Letters and will appear in the journal's print edition later this year, with UB chemistry graduate student Justin Bolton as lead author.

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"There's a lot of research in this area, but what our research team was able to accomplish is to expand the range of available pores to 50 nanometers in diameter, which was previously unattainable by block-copolymer-based methods," Rzayev continued. "Making pores bigger increases the flow of water, which will translate into cost and time savings. At the same time, 50 to 100 nm diameter pores are small enough not to allow any bacteria through. So, that is a sweet spot for this kind of application."

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http://dx.doi.org/10.1021/nl103747m

[klook]

1. Fantastic

I love technology sometimes. B-)

There should be a "We Are the World" type music fest to raise $ for this, with everyone playing nanoguitars: http://www.aip.org/png/html/nanotar.htm

[OKIsItJustMe]

2. On a related note, use your spare computer time to help with developing better nanofilters

http://www.worldcommunitygrid.org/research/c4cw/overview.do

Computing for Clean Water

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Approach

Normally, the extremely small pore size of nanotubes, typically only a few water molecules in diameter, would require very large pressures and hence expensive equipment in order to filter useful amounts of water. However, in 2005 experiments showed that such arrays of nanotubes allow water to flow at much higher rates than expected. This surprising result has spurred many scientists to invest considerable effort in studying the underlying processes that facilitate water flow in nanotubes.

This project uses large-scale molecular dynamics calculations - where the motions of individual water molecules through the nanotubes are simulated - in order to get a deeper understanding of the mechanism of water flow in the nanotubes. For example, there has been speculation about whether the water molecules in direct contact with the nanotube might behave more like ice. This in turn might reduce the friction felt by the rest of the water, hence increasing the rate of flow. Realistic computer simulations are one way to test such hypotheses.

Ultimately, the scientists hope to use the insights they glean from the simulations in order to optimize the underlying process that is enabling water to flow much more rapidly through nanotubes and other nanoporous materials. This optimization process will allow water to flow even more easily, while retaining sources of contamination. The simulations may also reveal under what conditions such filters can best assist in a desalination process.

[kristopher]

3. Not sure what the benefit is of this particular approach

There exists a number of inexpensive, low energy, high volume water filtering systems that not only filter bacteria but also virus. Just off the top of my head there was one I became familiar with when researching algae fuel systems was by GE called "Zeeweed".

Your post number #2 reminded me of this, which I think you posted a little while back:
Physicists discover new quantum state of water
http://physicsworld.com/cws/article/news/45037

[OKIsItJustMe]

4. Nanoporous Membranes Derived from Block Copolymers: From Drug Delivery to Water Filtration

http://dx.doi.org/10.1021/nn1014006

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Block-Copolymer-Derived Water Purification Membranes

Providing access to clean water is a global challenge that will ultimately require improvements in the current state of water filtration systems.(13) Improvements in the technology of filtration systems could provide more affordable clean water for all through industrial, municipal, or small-scale filtrations. Ultrafiltration is just one of the current technologies that could realize significant improvements in separation efficacy from the incorporation of nanoporous membranes prepared using block copolymers.

Typical UF membranes are either quite permeable and not very selective, as in the case of phase-inversion-type membranes, or selective and not that permeable, as in the case of track-etched membranes.(14) To compete successfully in the UF arena, four main criteria are typically needed: high selectivity, high permeability, mechanical integrity, and resistance to fouling.(15) Nanoporous membranes derived from block copolymers have tremendous promise to fulfill all four of those requirements due to their narrow pore size distributions (high selectivity), high porosity (high permeability), and tunable chemical and physical properties, yet research in the science and engineering of such membranes is needed to combine all of these attributes into practical systems. Because flux is inversely proportional to thickness and costs are directly related to amount of material used, separation membranes containing thin, selective block copolymer layers are most desirable.(16) Creative strategies, such as that demonstrated by Yang et al., are needed to produce selective membranes that are mechanically stable and compatible with application-specific chemical, thermal, and biological environments. Furthermore, fabrication hurdles such as achieving proper pore alignment and scalable fabrication steps must also be overcome.(3) We highlight recent progress made toward other block-copolymer-derived nanoporous separation membranes and some of the obstacles that still remain.

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(Parenthesized numbers are footnote references, follow the link for context.)