New tech uses sunlight to purify water

  • PTI, Tokyo
  • Updated: Jan 05, 2015 15:59 IST

A new Japanese technology that uses sunlight and photocatalysts to turn polluted water into safe drinking water is being tested in India.

The new system called 'Photocatalytic Water Purification Technology' has the ability to bind titanium dioxide (TiO2), a photocatalyst that reacts under ultraviolet light.

One of the difficulties associated with TiO2 is that it is difficult to collect once dispersed in water, since it comes in super fine particles.

Previous methods of binding it to larger matter have already been used, but they suffered a loss of active site surface area.

Japanese company Panasonic, which developed the new technology, has found a way to bind the TiO2 to another particle, zeolite (a commercial adsorbent and catalyst), which solves that problem by enabling photocatalysts to maintain their active site.

The method requires no binder chemicals because the two particles are bound together by electrostatic force.

When the photocatalytic particles are stirred, TiO2 is released from the zeolite and dispersed throughout the water.

As a result, reaction speed is much faster than other methods of fixing TiO2 on the surface of substrates, and a larger volume of water can be processed in a short amount of time, 'Gizmag' reported.

If the water is left still, it will cause TiO2 to bind to zeolite again, making it easy to separate and recover the photocatalysts from the water so they can be used again later.

Panasonic said it is working to lower costs and maintenance requirements with the water purification systems and aims to make this technology available right across India and other emerging nations.

Panasonic is working with a number of institutions in India to test the product and its capabilities.

The company said around 70% of the population of India relies on ground water, which is exposed to different types of pollution, from agrochemical residues to metals from leather tanneries.

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