IIT Mandi's self-cleaning glass can purify water using sunlight

Scientists at IIT Mandi have developed a self-cleaning glass that can remove microbes and organic pollutants -- like dyes, detergent and drugs -- from waste water, using only sunlight.

Waste water from pharmaceutical and textile industries are a major source of river pollution in India and abroad.

While existing purification techniques can remove solid pollutants as well as dissolved inorganic compounds, removing dissolved organic compounds remain a challenge, said Rahul Vaish, associate professor at Indian Institute of Technology (IIT) Mandi in Himachal Pradesh.

"Industries do not clean their waste water but simply dump it in the river. It is only after the river is contaminated completely that we think about taking action to clean the river," Vaish told PTI.

Instead, Vaish recommends the use of the process known as photocatalysis to treat the waste water before the harmful contaminants make there way into our river streams.

The team, which includes Gurpreet Singh and Sandeep Kumar, have developed a transparent calcium borate glasses and TiO2 crystallised glass nanocomposites which can kill microbes and break down organic chemicals in the presence of solar light.

"These glasses have photocatalytic and self-cleaning properties which help in destroying the bacteria and other microbes from wastewater in the presence of sunlight," said Vaish, corresponding author of the study published in the Journal of the American Ceramic Society.

"There is not extra cost or machinery involves. If the water is kept in this glass container it will treat the organic compounds in a few hours. You only need sunlight," he said.

The technology has a range of applications, the researcher said.

These easy to fabricate glasses can be made in the form of large panels which can have a wide range of applications from self-cleaning water bottles to large cleaning tanks for industrial discharge.

"The glass can also remove detergents from water. It could be used in washing machines to clean the water at the discharge point itself, rather than letting the contaminated water flow into our river systems," Vaish said.

Removal of such toxic chemicals from water is successfully demonstrated by many researchers at a laboratory scale.

However, cost and efficiency associated with existing technologies are major hurdles in their commercial usage.

Vaish said that his fabrication process is cost-efficient.

"This technology can also be used to clean air. It can remove NOx (oxides of nitrogen) from the air. If we place these glasses in our windows, we can fight air pollution too," he said.

"We are trying to improve transparency off the glasses so that they can be used to replace regular windows," Vaish added.