Introduction to nanotube desalination

Nanotube desalination is not yet commercially viable.  It is, however, an extremely promising technology.  Nanotubes are tubular structures at the atomic nanometer-scale.

One issue with conventional polymer membranes is that the pore-size distribution leads to inefficiency.  The use of nanotubes can increase pore uniformity, increasing permeability while simultaneously increasing salt and contaminant rejection.  Nanotube’s smooth hydrophobic walls can also reduce friction, increasing flux rate beyond the levels associated with the higher permeability.

While the word nanotube is often used as a synonym for carbon nanotube, they can be made out of many substances.  The most researched nanotubes are made from carbon and boron nitride.

Carbon nanotubes

Carbon nanotubes (CNT) are probably the most researched.

Boron nitride nanotubes

Boron nitride nanotubes (BNNT) are reported to get higher water flux rates than CNTs. Their high heat resistance, however, makes them more expensive to manufacture than CNTs.