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Overcoming the challenges to desalination

The earth comprises of 97.5% water. Freshwater covers about 2.5% of the planet. Out of this freshwater, 31% is available for use and glaciers and ice caps cover 69%. Therefore, less than 1% of freshwater is available for drinking purposes. The vast percentage of water in the oceans and seas are subjected to the process of desalination to increase the scale of drinking water. Since water from seas and oceans are salty, the process of desalination separates salts and other minerals from the sea or brackish water to convert it into potable water. Methods of desalination include reverse osmosis, distillation, freezing, flash evaporation, hydrate formation, and electrodialysis.


However, the process of desalination is most often expensive and power-consuming. It is not feasible. The sources of freshwater are dwindling every day. Hence, it is becoming harder to supply potable water to the ever-growing population with such expensive processes. Research performed at Northeastern University has shown much promise to eradicate this problem. According to this research, nanotubes are the answer. The chemical nature of water makes it harder for the hydrogen (H) molecules to separate from each other for the filtering process. A carbon nanotube comes with the best approach. The diameter of a nanotube is 0.8nm, 50,000 times narrower than the width of a human hair, that is, 50 to 70 mm. The small and minuscule size of this tube forces the water molecules to separate. Therefore, they form a single file to enter the tubes for desalination.


In addition to its size, the carbon nanotubes possess negative electric charges. This charge makes them repel/reject other negative charges such as the negative ions in salt or other unwanted particles. The Northeastern University has also collaborated with scientists at the Lawrence Livermore National Laboratory in California for this research. The researchers believe that this method of desalination is better than any other existing natural or man-made methods. They also hope to start programs for students to learn this method to alleviate the drinking water crisis.


Dibyasha Das