Water permeation in carbon nanotube membranes

•Ultra-high pure water flow rates observed in carbon nanotubes: are they real?•Can high selectivity, high permeability carbon nanotube membranes be manufactured?•Analysis of current fundamental and technological challenges toward CNT membranes.

Water treatment is one of the main battlegrounds in the world's effort to reduce greenhouse gas emission and global warming: ever greater amounts of energy are required in developed countries to treat water to ever increasing quality standards; wastewater treatment and sea-water desalination plants are often out of reach of those developing countries that need it the most, due to high energy and capital requirements. In this opinion paper we argue that nanotube membranes have the potential to change this dynamic by lowering overall costs of filtration processes. We discuss current limitations and the latest developments toward commercialization of this technology.