How Yo Make Sea Water Drinkable

Graphene-oxide membranes have attracted considerable attention as promising candidates for new filtration technologies. Now the much sought-after development of making membranes capable of sieving common salts has been achieved. New research demonstrates the real-world potential of providing clean drinking water for millions of people who struggle to access adequate clean water sources. Graphene-oxide membranes developed at the National Graphene Institute have already demonstrated the potential of filtering out small nanoparticles, organic molecules, and even large salts. Until now, however, they couldn’t be used for sieving common salts used in desalination technologies, which require even smaller sieves. Previous research at The University of Manchester found that if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, but larger ions or molecules are blocked.

The Manchester-based group have now further developed these graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water. The pore size in the membrane can be precisely controlled which can sieve common salts out of salty water and make it safe to drink.


Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology,” says Professor Rahul Raveendran Nair.

The new findings from a group of scientists at The University of Manchester have been published in the journal Nature Nanotechnology.


Nanotechnology Boosts Solar Panel Efficiency

Solar power, which is power drawn from the sun, is a familiar concept for most Americans. You set out some thick, flat arrays the color of blueberries in your lawn or on your roof, and they use the photovoltaic effect to generate a current. For many people, this means they can expect to spend less on energy from nonrenewable sources like oil and gas, with the added benefit of reducing carbon emissions in the long run. The benefits for developing nations are even greater. Take Africa, for example. As a continent, it is extremely sunny and flat so it seems like a natural place to deploy solar panels. The main barriers preventing this rollout are the cost of cell production and limitations on cell efficiency.

solar farm

Fortunately, research costs for solar energy are comparatively lower than other fields. This has led to scientists coming up with a number of inventive ways to improve solar cells through the use of nanotechnology.
Nanotechnology refers to manmade matter measuring between 1 and 100 nanometers (nm). For reference, a sheet of paper is 100,000 nm, while a strand of hair is 80,000 nm. Due to their size and extreme variety, nanotechnology allows scientists to create microscopic components and enhance the performance of existing technologies. For example, electroplating solar panels with nanometers-thin layers of silver helps the system absorb heat and makes it resistant to corrosion. Hinging on the size and versatility of nanotechnology, scientists have discovered several different ways to leverage it to improve solar cells.

The amount of energy solar cell panels can produce is limited in part by the sunlight it collects. If the array can collect more sunlight while still taking up the same amount of space, the energy produced per panel will increase. This would have a profound effect on arrays in places like Africa, where it is extremely sunny. The increase in surface area would mean a greater amount of energy collected and output over the lifetime of the cell. Using nanotechnology, scientists have developed a way to do just this.

The actual product is called a dye-sensitive solar cell. It uses a layer of porous nanoparticles coated in dye to increase the surface area on the solar cell on a microscopic level. This has the added benefit of making the cell more flexible, and increasing its ability to work in extreme conditions. If that seems difficult to imagine, think about it this way: Picture a long strip of candy dots. The paper is the solar array while the candy is the layer of nanoparticles. The candy increases the surface area of the paper without adding much bulk. Thus, the paper remains supple. Some of the greatest advances in flexible solar cells have been made by Alberta scientist Jillian Buriak. Using a spray gun and laminators, Buriak and her team developed a way to spray nanoparticles onto the plastic. This sheet is then run through the laminator, which spreads out the layer even further. The result is an extremely thin solar cell with innumerable practical applications.

Using nanotechnology, scientists have discovered that they can create cells that absorb 90 percent of the sunlight that hits it. This allows for more efficient concentrating solar power (CSP) plants. Unlike traditional solar arrays, CSP plants generate power by focusing the sun, generally through mirrors, on molten salt. The heated salt is used to create steam to turn a turbine and generate electricity. One limitation of these plants is that the materials used to collect the sunlight degrade after about a year, causing a dip in production while they are repaired.

This new technology can withstand extreme heat and last for many years outdoors, despite exposure to the elements.


Water To Drink From The Sea

University of Illinois (U. of I.) engineers have found an energy-efficient material for removing salt from seawater that could provide a rebuttal to poet Samuel Taylor Coleridge’s lament, “Water, water, every where, nor any drop to drink.” The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out, a process called desalination. In a study published in the journal Nature Communications, the Illinois team modeled various thin-film membranes and found that MoS2 showed the greatest efficiency, filtering through up to 70 percent more water than graphene membranes.


Even though we have a lot of water on this planet, there is very little that is drinkable,” said study leader Narayana Aluru, a U. of I. professor ofmechanical science and engineering. “If we could find a low-cost, efficient way to purify sea water, we would be making good strides in solving the water crisis”.
Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time,” said Aluru, who also is affiliated with the Beckman Institute for Advanced Science and Technology at the U. of I.

Most available desalination technologies rely on a process called reverse osmosis to push seawater through a thin plastic membrane to make fresh water. “Reverse osmosis is a very expensive process,” Aluru said. “It’s very energy intensive. A lot of power is required to do this process, and it’s not very efficient. In addition, the membranes fail because of clogging. So we’d like to make it cheaper and make the membranes more efficient so they don’t fail as often. We also don’t want to have to use a lot of pressure to get a high flow rate of water.


Cars: NanoMaterial Resists Under Extreme Conditions

Material researchers at the Leibniz Institute for New Materials (INM) – Germany – will be presenting a composite material which prevents metal corrosion in an environmentally friendly way, even under extreme conditions. It can be used wherever metals are exposed to severe weather conditions, aggressive gases, media containing salt, heavy wear or high pressures.
From 7 to 11 April 2014, the researchers of the INM will be presenting this and further results in Hall 2 at the stand C48 of the Hannover Messe in the context of the leading trade fair for R & D and Technology Transfer. This includes new developments of transparent and conducting coatings, CIGS solar cells, antimicrobial coatings as well as grease-free composites with corrosion-resistant properties and printed electronics.

This patented composite exhibits its action by spray application”, explains Carsten Becker-Willinger, Head of the Nanomers Program Division. “The key is the structuring of this layer – the protective particles arrange themselves like roof tiles. As in a wall, several layers of particles are placed on top of each other in an offset arrangement; the result is a self-organized, highly structured barrier”, says the chemical nanotechnology expert. The protective layer is just a few micrometers (1 thousandth of a millimeter) thick and prevents penetration by gases and electrolytes. It provides protection against corrosion caused by aggressive aqueous solutions, including for example salt solutions such as salt spray on roads and seawater, or aqueous acids such as acid rain. The protective layer is an effective barrier, even against corrosive gases or under pressure.


Salt, Key Element To Mass Production Of Nanostructures

Chemists at Oregon State University have identified that salt could significantly reduce the cost and potentially enable the mass commercial production of silicon nanostructures – materials that have huge potential in everything from electronics to biomedicine and energy storage. Simple sodium chloride, most frequently found in a salt shaker, has the ability to solve a key problem in the production of silicon nanostructures, researchers just announced in Scientific Reports, a professional journal. By melting and absorbing heat at a critical moment during a “magnesiothermic reaction,” the salt prevents the collapse of the valuable nanostructures that researchers are trying to create. The molten salt can then be washed away by dissolving it in water, and it can be recycled and used again.

silicon nanostructure 2

This could be what it takes to open up an important new industry,” said David Xiulei Ji, an assistant professor of chemistry in the OSU College of Science. “There are methods now to create silicon nanostructures, but they are very costly and can only produce tiny amounts“. “The use of salt as a heat scavenger in this process should allow the production of high-quality silicon nanostructures in large quantities at low cost,” he said. “If we can get the cost low enough many new applications may emerge.”