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Desalination of seawater without electricity
Why is it in news?
- Researchers at the Tata Institute of Fundamental Research (TIFR), Mumbai, have been able to desalinate seawater to produce drinking water with the help of gold nanoparticles that absorb sunlight over the entire visible region and even the near infrared light.
Desalination & Reverse osmosis
- Desalination:(1) Desalination is a process that takes away mineral components from saline water.(2) More generally, desalination refers to the removal of salts and minerals from a target substance.
- Reverse osmosis:(1) The leading process for desalination in terms of installed capacity and yearly growth is reverse osmosis (RO).(2) The RO membrane processes use semipermeable membranes and applied pressure (on the membrane feed side) to preferentially induce water permeation through the membrane while rejecting salts.
More in news
- No need of external energy: Unlike the conventional reverse osmosis that is energy intensive, the gold nanoparticles require any external energy to produce potable water from seawater.
- Experiment:(1) Team used 2.5 mg of gold nanoparticles and was able to use sunlight to heat the water to 85 degree C and generate steam to produce drinking water from seawater.(2) Since the temperature reached is high, about 10% of seawater becomes steam (and hence drinking water) in about 30 minutes.(3) Alternatively, the gold nanoparticles can be used to convert carbon dioxide into methane.(4) This happens when the light absorbed by the gold nanoparticles excites the electrons, and the excited electrons when transferred into carbon dioxide converts it into methane in the presence of hydrogen.(5) The hydrogen comes from the water that is used as a reaction solvent.
Source
The Hindu