Given that current desalination technologies cost millions
of dollars and huge energy input to run it, will the newfangled graphene-based
desalination devices drastically cut costs and energy consumption?
By: Ringo Bones
According to the United Nations, it is expected by the year
2025 14-percent of the world’s population will encounter water scarcity. Given
that the current “most energy efficient” way to desalinate water – i.e. reverse
osmosis desalination plants – still costs hundreds of millions of dollars to
build and their energy requirements is beyond that of a remote small town in
sub-Saharan Africa to generate. Fortunately, a new wonder material, like graphene,
could drastically slash the energy and cost requirements to build a
desalination plant big enough to provide potable water to a typical out of the
way small town.
Graphene-oxide membranes have attracted considerable
attention as promising candidates for new filtration technologies, especially
ones that are less expensive and require lower energy to operate than existing
ones. Now the much sought-after development of making membranes capable of
sieving common salts has been achieved. New research demonstrates the
real-world potential of providing clean drinking water for millions of people who
struggle to access adequate clean water sources.
When common salts are dissolved in water, they always form a
“shell” of water molecules around the salt’s molecular structure. This allows
the tiny capillaries of the graphene-oxide membranes to block the salt from
flowing along with the water. Water molecules are able to pass through the
membrane barrier and flow anomalously fast which is ideal for application of
these membranes for desalination.
Professor Rahul Nair at the University of Manchester said “Realisation
of scalable membranes with uniform pore size down to atomic scale is a
significant step forward and will open new possibilities for improving the
efficiency of desalination technology”. Prof. Nair’s experimental desalination
device at the National Graphene Institute of Manchester uses a one-atom thick graphene
filter.
