IIT Bombay scientists develop lotus leaf-like solar evaporat
IIT Bombay scientists develop lotus leaf-like solar evaporators for saltwater treatment
Scientists at the Indian Institute of Technology (IIT) Bombay have developed a new hydrophobic graphene-based material that could support efforts to address the freshwater crisis
NEW DELHI — Scientists at the Indian Institute of Technology (IIT) Bombay
have developed a new hydrophobic graphene-based material that could support
efforts to address the freshwater crisis.
Freshwater scarcity is a significant issue in various
parts of the world and is expected to intensify in the coming years.
While water is abundant on Earth's surface, only about 3
per cent of it is freshwater, and even within that, less than 0.05 per cent is
easily accessible.
While removing salt (desalination) from seawater and
brackish water is a solution, desalination is a big problem in landlocked
places.
The team led by Prof. Swatantra Pratap Singh developed
the new material called the Dual-Sided Superhydrophobic Laser-Induced Graphene
(DSLIG) evaporator.
DSLIG evaporator can be heated via both solar heating and
electricity (known as Joule heating).
By combining solar and electric heating, the material is
protected from fluctuations in the availability of sunlight.
When there is less or no sunlight, electricity can be
used to heat the evaporator and maintain similar temperatures, ensuring
consistent performance.
Further, DSLIG has a superhydrophobic property, meaning
it repels water like lotus leaves.
Owing to the characteristics of their surfaces,
superhydrophobic materials reduce the contact area between water droplets and
the material surface, making droplets roll over them instead of wetting.
In desalination applications, the superhydrophobic nature
of DSLIG helps prevent salt dissolved in water from sticking to the evaporator
surface, thus maintaining efficiency over time.
“The primary goal of our work was to create a
superhydrophobic surface, exhibiting the lotus effect, capable of functioning
with both solar and Joule heating,” Prof. Singh said.
The researchers fabricated DSLIG by coating a layer of a
polymer called polyvinylidene fluoride (PVDF) on one side of a thin layer of
another polymer LIG, poly(ether sulfone) (PES).
Graphene was then engraved on the PVDF polymer side of
the material using laser-based engraving technology.
Laboratory tests show that DSLIG exhibits lotus leaf-like
behaviour, and also prevents salt deposition. It showed excellent efficiency
for desalination under both electric and solar heating, and in treating
extremely concentrated salt solutions.
DSLIG comes with a low carbon footprint, low toxicity,
and cost-effectiveness making it a potential candidate for large-scale
sustainable desalination applications and the treatment of industrial
wastewater.
