Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



WATER WORLD
Active sieving could improve dialysis and water purification filters
by Staff Writers
Washington DC (SPX) Oct 18, 2017


To separate molecules usually a "colander" type of filter is used (Left side). A new type of filter, where the holes of the sieve can be activated is explored. (Right side) Thanks to an external power input, the holes of the sieve (here doors) can be opened and closed. This power input plays the role of a crazy Maxwell Demon -- similar to a bouncer.

Physicists from Ecole Normale Superieure and Paris Science and Letters University in France have proven theoretically that active sieving, as opposed to its passive counterpart, can improve the separation abilities of filtration systems.

These new views on how active sieving could improve systems such as those used in water purification and dialysis were reported this week in The Journal of Chemical Physics, from AIP Publishing. Active sieving also has the potential to filter molecules based on movement dynamics, opening up a whole new avenue in the field of membrane science based on the ability to tune osmotic pressure.

Sieves, from kitchen colanders to complex dialysis machines, all have "passive" pores to filter out unwanted molecules from the desired product. While straining spaghetti is a simple example, the filtering of specific molecules on the nanoscale level for biomedical applications and for production of clean water is a complex and costly process. Any improvements to this process are the subject of much investigation.

Active sieving replaces the passive holes in a sieve with doorlike openings that open and close according to external commands. These active pores can precisely discriminate between molecules and be switched on and off depending on the exact sieving conditions. Therefore, active sieving gives a level of dynamic control that we do not possess in current filtration systems.

The researchers investigated a few types of external commands to control the doors of a sieve's pores, including a mechanical 'shake' and an electrical signal to change the charge guarding the doorways.

"We put together a general framework to describe holes in the membrane that have some kind of dynamic aspect to them that you could externally modify," said Sophie Marbach at the Ecole Normale Superieure. "It's an exciting proposition because it is a new concept and we don't know what it is going to lead to."

One of the possibilities is that molecules could be actively sorted, i.e., sort the fast-moving molecules separately from the slow based on their dynamic properties. This would be helpful in making fine distinctions between very similar molecules and is already known to occur in nature. For instance, the KscA pore, a potassium channel found in soil bacteria, is thought to select potassium using its speed to distinguish it from the very similar sized and charged sodium.

The "osmotic pressure" of a filter is critical for molecules to move through the nanopores, but actively changing pores alters the osmotic pressure and changes the status quo. This suggests that the tuning of the osmotic pressure could be harnessed to further evolve sieving techniques.

"Because the theoretical framework is at an early stage it is not obvious to know the consequences of what will happen," Marbach said. "There are a lot of theoretical questions lingering around."

Research Report: "Active sieving across driven nanopores for tunable selectivity"

WATER WORLD
Wither heavy storms
Santa Barbara CA (SPX) Oct 18, 2017
The Colorado River tumbles through varied landscapes, draining watersheds from seven western states. This 1,450-mile-long system is a critical water supply for agriculture, industry and municipalities from Denver to Tijuana. In the drylands of the Colorado's lower basin, formed by Nevada, Arizona and California, thunderstorms - known in meteorological parlance as convective precipitation - ... read more

Related Links
American Institute of Physics
Water News - Science, Technology and Politics


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

WATER WORLD
Mexico quake hit rich and poor alike, but tragedies differ

ESA takes the reins of the Disasters Charter

Thousands still without power in Ireland after freak storm

Risking lives, Mexicans try to salvage belongings after quake

WATER WORLD
Understanding rare earth emulsions

Missing link between new topological phases of matter discovered

Space radiation won't stop NASA's human exploration

Saab upgrading Norwegian radars under NATO contract

WATER WORLD
Wither heavy storms

Toward efficient high-pressure desalination

Huge spike in global carbon emissions linked to El Nino

'Thirsty protests' hit Morocco over water shortages

WATER WORLD
As ice sheet melts, Greenland's fjords become less salty

Thousands of penguin chicks starve in Antarctica

The melting ice makes the sea around Greenland less saline

Formation of coal almost turned our planet into a snowball

WATER WORLD
Little growth observed in India's methane emissions

India to close colonial-era military farms

Smallscale farmers try to solve Amazon's big problems

Genetically boosting the nutritional value of corn could benefit millions

WATER WORLD
Lake waves penetrate, disturb the surrounding earth

Vietnam braces for more downpours as flood toll hits 72

Climate-disrupting volcanoes helped topple ancient Egypt: study

Scientists determine source of world's largest mud eruption

WATER WORLD
Chad extends key conservation area in national park

Rwanda military uses torture to force confessions: HRW

New witness emerges over Rwandan genocide: French legal source

Nigeria: Cooperation 'key' to defeating jihadists

WATER WORLD
New study suggests that last common ancestor of humans and apes was smaller than thought

World Bank: 1.1 bn people 'invisible', lacking official identity

DNA proves Newfoundland was populated by distinct groups three different times

Scientists identify genes critical for hearing




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement