Ultra-Thin Nanotubes Desalinate Seawater

Scientists developed new carbon nanotubes that are more than 50,000 times thinner that human hair and can quickly as well as effectively separate the salt from seawater. This is an advance that might help to solve the world’s water crisis.

The increasing demand for more fresh water is posing a worldwide threat to sustainable development, which results in water being a scarcity for more than 4 billion people around the world, said researchers.

Current technologies for water purification can benefit from this type of membrane development with specialized pores, which mimic water selective and highly efficient biological proteins.

Scientists from Northeastern University in Boston amongst others developed the carbon nanotube pores which can exclude the salt in seawater.

The team of researchers found that the water permeability in the carbon nanotubes or CNTs, that have a diameter of 0.8 nanometers exceeds that of carbon nanotubes that are wider by a significant proportion.

The nanotubes, which are hollow structures made out of carbon atoms that are arrangement in a unique order, are over 50,000 times thinner than a single human hair follicle.

The inner surface is super smooth inside the nanotube making for remarkable permeability of water, while the tiny size of the pores block the larger ions of salt.

One researcher said that his research team has found that nanotubes that have a diameter less than a nanometer have an important structural feature enabling enhanced transport.

The very narrow hydrophobic channel is able to force water into a single-file lineup, a phenomenon that is similar to that which is found in the most efficient water transporters said the researcher.

Computer experimental studies and simulations of water transport via the CNTs that have diameters of more than one nanometer indicated more water flow, but did not match transport efficiency of the biological proteins as well as did not make an efficient separation of salt from seawater, especially when the water had higher salinities.

The important breakthrough that the research time achieved was to use nanotubes of a smaller diameter that gave the required performance boost in salt separation.

Researchers said that carbon nanotubes contain unique platforms for studying Nano fluidics and molecular transport. Their size being sub-nanometer, surface being atomically smooth, and similar to cellular channels for water transport make them very well suited for the purpose of salt separation and even better than nature’s method.

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