Researchers at IIT Mandi have created recyclable sponges incorporated with soot emitted by diesel engines that can mop up oil and other organic pollutants from water.

Diesel engines are known to emit significant amounts of soot, which is formed in the fuel rich regions of the burning diesel jets.

Increasing environmental concerns, as well as stringent emission standards require new ways to reduce this soot, researchers said.

Rahul Vaish, associate professor at Indian Institute of Technology (IIT) Mandi, along with his research students Vishvendra Pratap Singh and Moolchand Sharma said that while it is impossible to bring down soot emissions to zero, it is possible to find use for the soot produced.

It is known that carbon species can adsorb various organic pollutants in water, researchers said. 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.

"There is a rapid increase in oil and chemical leakages from oil tankers or ships and industrial accidents with expansion in oil production and transportation in the last few decades," researchers wrote in the study published in the journal published in the journal Environmental Science and Pollution Research.

Previously, Vaish had 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 earlier 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 need for complex pre treatments. An interesting observation was that the sponges were recyclable and retained 95 per cent efficiency even after 10 cycles.

The diesel soot impregnated sponge could also absorb pollutants like methylene blue, ciprofloxacin, and detergent from the water. This has practical implications, researchers said.

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

The soot impregnated sponge can help in developing cost-effective remediation processes for common domestic and industrial pollutants. Such a development would additionally serve to repurpose automobile waste.

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