Carbon nanotubes may revolutionise the process of converting salt water to fresh water and provide an energy-saving solution to the increasing global demand for fresh drinking water, researchers say.
In a new report, computer modelling was used to study how fluid flows at the molecular level. One of their aims was to find the optimum design for a carbon nanotube (CNT) membrane that can be used in the desalination process.
Thee simulations suggest that this membrane may be 20 to 5,000 times more permeable to water than current commercial scale reverse osmosis membranes, depending on tube density.
“If a new material is found that can maximise water transport through the separating membrane, while at the same time rejecting dissolved ions and other particulates in seawater, reverse osmosis would be a much more efficient process,” said lead author Jason Reese, professor of thermodynamics and fluid mechanics at the University of Strathclyde, Glasgow, Scotland.
Demand for drinking water on the increase
With the global population predicted to reach 9.5 billion by the latter half of this century, the demand for drinking water is only going to increase. Already, more than a billion people are faced with insufficient fresh water resources.
This week, 20 former heads of state, including former U.S. president Bill Clinton and former Japanese prime minister Yasuo Fukuda, warned of an impending "water crisis", and will establish a panel to tackle a worldwide leadership gap on the issue.
Trends in climate change have been shown to predict a redistribution of rainfall globally, with dry regions of the planet only getting dryer.
Huge costs of desalination
Most desalination plants convert salt water to fresh water using reverse osmosis. Pressure is applied to the salt water solution forcing the water through a permeable membrane that separates the pure water from the salts.
There are huge costs associated with desalination plants, however, as they require expensive infrastructure and large amounts of energy. With current technology, it is five times more expensive to desalinate water than to extract groundwater, but CNTs may change this.
Carbon nanotubes are sheets of graphene – one-atom thick carbon – rolled into cylinders. Their versatility lies in the fact that they can be a nanometre in diameter, with a tube length many millions of times longer. They are highly efficient at repelling salt ions. In solution, salts are surrounded by hydrating water molecules, which must be shed in order to pass through the CNTs.
This process takes a lot of energy and as a result doesn’t happen very often. Therefore, the right sized nanotube will optimise water transport while minimising salt ion permeability.
41% of Americans Support Criminalizing "Hate Speech" 2015-05-23 7:31 The following are from a recent poll about what some are calling on for "hate speech"
1. Support for Hate Crimes Legislation
Do you support or oppose the federal law that requires increased penalties for hate crimes committed on the basis of the actual or perceived race, color, religion, national origin, ethnicity, or gender of any person?
2. Support for Expanding Hate Crimes
FBI Admits No Major Cases Cracked with Patriot Act Snooping Powers 2015-05-23 7:36
FBI agents canâ€™t point to any major terrorism cases theyâ€™ve cracked thanks to the key snooping powers in the Patriot Act, the Justice Departmentâ€™s inspector general said in a report Thursday that could complicate efforts to keep key parts of the law operating.
Inspector General Michael E. Horowitz said that between 2004 and 2009, the FBI tripled its use of bulk ...
Sweetener Stevia Was Once Hailed As An Anti-Fertility Agent for Population Reduction 2015-05-23 7:13
Maybe it's not so sweet now... If you've thought stevia, the natural alternative to sugar and artificial sweetners with aspartame, et al., is too good to be true, there may be a catch. Check out this textbook written in 1970 by Paul and Anne Ehrlich, the precursor to the textbook Ecoscience they wrote with Obama Science Czar John P. Holdren ...
TPP Aproved: Senate Republicans Give Obama New Powers - Details Remain 'Classified' 2015-05-23 6:43
President Obama won a big victory for his trade agenda Friday with the Senateâ€™s approval of fast-track legislation that could make it easier for him to complete a wide-ranging trade deal that would include 11 Pacific Rim nations.
A coalition of 48 Senate Republicans and 14 Democrats voted for Trade Promotion Authority late Friday, sending the legislation to a difficult fight ...
Circumcision battle: Mom seeks release from jail after federal lawsuit is dismissed 2015-05-23 3:22
West Boynton mother on Wednesday gave up trying to get a federal judge to stop her 4 1/2-year-old son from being circumcised as his father wishes â€” a battle that also led to her arrest May 14 on a state court warrant.
An attorney for Heather Hironimus, who lost similar legal challenges in two state courts, notified U.S. District Judge Kenneth ...