IIT team uses diesel soot to mop up oil, pollutants from water

Dipender Manta
Tribune News Service
Mandi, February 21

Researchers at the Indian Institute of Technology (IIT), Mandi, have used the soot emitted by diesel engines to mop up oil and other organic pollutants from water. Their work has been recently published in the journal ‘Environmental Science and Pollution Research’.

Dr Rahul Vaish, Associate Professor, School of Engineering at IIT-Mandi and his research students Vishvendra Pratap Singh and Mool Chand Sharma have looked at this problem from a different perspective. They rationalised that while it was impossible to bring down soot emissions to zero, it was possible to find use for the soot produced.

He said carbon species such as carbon nanotubes, graphene, and candle soot had shown their potential in many fields. Then why not automobile soot?

According to study, it is known that carbon species can absorb various organic pollutants in water. Carbon nanotubes, filter paper, mesh films, and graphene have been used for removing oil from water. Given that the typical carbon content of soot is between 90 and 98 per cent, the team explored the possibility of using this pollutant as an adsorbent of oil and organic contaminants in water.

In an earlier study, Dr Vaish used candle soot to successfully remove two cationic dyes, rhodamine B and methylene blue from water, thereby showing the possibility of organic chemical removal by soot. Extending this previous work, the research team incorporated diesel exhaust soot into polymer sponges to study their capability to adsorb oil and other organic materials from water.

This hydrophobic sponge showed high absorption capacity for various oils, without the need for complex pre-treatments. The researchers found that the highest oil absorption capacity was 39 g/g for engine oil. An interesting observation was that the sponges were recyclable and retained 95 per cent efficiency even after 10 cycles.

“Apart from oil spills, organic pollutants, such as traces of dyes and detergent coming from industries and households, are a major contributor of water pollution” said Dr Vaish. 

Environmental concerns 

• Although diesel engines are known to be superior to other internal combustion engines in terms of lower fuel consumption and better energy release efficiencies, they are associated with significant amount of particulate emissions
• The particulates largely comprise soot, which is formed in the fuel-rich regions of the burning diesel jets. Increasing environmental concerns and stringent emission standards require development of both conventional and unconventional means for reducing soot 
• Studies in this area have focused on improving the engine design and incorporating special filters and treatment units at the exhaust end of the vehicle