New desalination process uses carbon nanotubes

March 15, 2011

A new desalination process enhanced by carbon nanotubes has been developed by New Jersey Institute of Technology researchers.

Membrane distillation is a water purification process in which heated salt water passes through a tube-like membrane, called a hollow fiber. It allows only water vapor to pass through the walls of the hollow tube, but not the liquid, says Professor Somenath Mitra.

Conventional approaches to desalination are thermal distillation and reverse osmosis. Mitra’s new method creates a better membrane by immobilizing carbon nanotubes in the pores. It increases vapor permeation but also prevents liquid water from clogging the membrane pores. Test outcomes show dramatic increases in both reductions in salt and water production.

The new process can facilitate membrane distillation at a relatively lower temperature, higher flow rate, and higher salt concentration, according to Mitra. Compared to a plain membrane, this new distillation process demonstrates the same level of salt reduction at a 20°C lower temperature, and at a flow rate six times greater.

Their work appears in the American Chemistry Society journal Applied Materials & Interfaces.