Compared with reverse osmosis, capacitive deionisation reduces operating costs, energy consumption and CO2 emissions.
One of the most promising technologies for the desalination of seawater is capacitive deionisation. This enables all types of ionic species to be eliminated from water with different levels of salinity and competes with reverse osmosis, today’s most commonly implemented technology; reducing operating costs and energy consumption and, consequently, CO2 emissions.
The technology developed contemplates the application of electrical potential between the pairs of electrodes that make up the CDI cell, forcing the ions from the saline solution, which pass through them, to be absorbed on their surface. The electrochemical based process purifies saline and stores energy at the same time.
Saline water and capacitive deionisation
The capacitive deionisation concept dates back to the 1960s. However, treatment of saline water with concentrations in excess of 5 g/l has been a long way off its practical application due to the lack of appropriate material for the electrodes.
To address this need, a new hybrid material has been developed that has a combination of macropores, mesopores and micropores in a three-dimensional structure with reduced graphene oxide. This structure, combined with the hydrophilic and capacitive effect of the metal oxide nanoparticles, has proven to be highly efficient in the elimination of salt from water of different levels of salinity.
Capacitive deionisation using graphene-based electrodes is a promising, innovative and sustainable technology for the desalination of water of different levels of salinity with low energy consumption.