New solar technology can mass produce drinking water

Called & other; Solar distillation apparatus & throughout; Tank equipment can use the sun evaporates water or salt water, and the steam condenses into safe drinking water. But large and expensive distiller can only provide enough water for a small family. Now, researchers have developed a kind of new material, can accelerate the evaporation process, make the small solar still, which can provide a family all the drinking water. If the technology is proved that cheap enough, it will be able to provide clean drinking water for millions of poor people.

the United Nations children's fund, according to data from today, there are 7 around the world. 8. 3 billion people, or nearly 1/10 of the population don't have access to the service. These people spent a total of two hundred million hours every day draw water from far away. Although there are sewage treatment and desalination technology, but these techniques generally require expensive infrastructure and a large amount of energy, which makes many community cannot afford.

recently, researchers have focused on solar distiller upgraded to substitute for a cheap, low technical content. The traditional distiller is just a black container filled with water, the top is transparent glass or plastic cover. Black at the bottom of the absorb sunlight, heating water, evaporation, and pollutants. Then the water vapor condensation on the transparent cover, finally slowly into a collector.

but, as the sun must before the start of the evaporation heat total volume of water, causing water output is very low. Commercially available version of every square metre coverage area is produced per hour is about 0. 3 litres of water ( L / h / m2) 。 A person needs about 3 liters of water every day. For a small family with enough drinking water area of about 5 square metre. In theory, under the best operation state of the device, can only have 1. 6 L/h/m2。

the university of Texas at Austin, a materials scientist Guihua Yu and his colleagues recently reported a new method of bypass this limit. It includes water gel, and form a network of three-dimensional porous absorbent polymer mixture.

Yu and his colleagues used two kinds of polymer & ndash; — Called a poly (vinyl alcohol) ( PVA） Water combined with polymers, another called polypyrrole ( PPy) The light absorption agent & ndash; — They produced a type of gel foam, and then put them in a solar energy on the surface of the distiller.

in the gel, a layer of water molecules bind to PVA and each layer of water molecules formed multiple bonds, known as the hydrogen bond. But because most of their bonding capacity are associated with PVA, loosely bound water molecules can combine with other water molecules near, finally formed Yu said & other; Throughout the middle water &; 。

the middle chemical bonding between water molecules and the adjacent water molecules is less, so they are more likely than plain water to evaporate. In this case, they would immediately replaced by other water molecules in the distillation apparatus.

use this technique, Yu's solar still, which can produce 3. 2 L/h/m2 of water, which is twice the theoretical limit value. Yu's team last year in nature & ndash; Nanotechnology journal reported the research results.

today, Yu and his colleagues have developed a better water gel. The hydrogel mixed with the third kind of polymer chitosan, which can strongly absorb water. To join in the mixture of chitosan can form a gel that can hold more water, thereby increasing the number of intermediate water.

on June 28, the researchers report in the journal science progress, the use of this new type water gel distilled water solar stills to 3. 6 L/h/m2 the speed of the work, this is the highest rate of reported so far, about 12 times of similar products on the market at present.

　　“ This is a very good starting point. ” Saudi Arabia figure Mr King abdullah university of science and technology, environmental engineer Peng, Wang said. Wang pointed out that under such a high water production rate, 1 square meters of solar still, which can produce about 30 litres of clean water every day, enough for a small family.

and he said, even better, all the three kinds of polymer in the hydrogel is commercial, and the price is cheap. This means that if you use these polymer distiller is strong enough, they can offer those most in need of clean drinking water.