IISc Develops Nanomaterial to Clean Chromium from Groundwater

September 20, 2024

Researchers at the Indian Institute of Science (IISc) have made an important discovery by developing a special nanomaterial that can help reduce heavy metal contamination in groundwater, particularly focusing on chromium pollution. This is crucial because heavy metals in water are a growing environmental concern, especially in urban areas affected by industrial waste.

What is Chromium Contamination?

Chromium is a toxic metal that often gets into the soil and groundwater because of waste from industries like leather tanning, electroplating, and textile manufacturing. Traditionally, the solution involves removing the contaminated water and sending it to treatment plants where it is cleaned through chemical and physical processes.

A New Way to Clean Water On-Site

The IISc team came up with a new way to clean the water directly at the contamination site. They use iron nanoparticles that are injected into the groundwater, where they react with chromium to clean the water on-site, avoiding the need to transport it to another location for treatment.

The team first created nano zero-valent iron (nZVI), which is a type of iron that can reduce harmful chromium (Cr6+) to a safer form (Cr3+). However, these iron nanoparticles had a tendency to clump together, which made them less effective.

Preventing Clumping with Carboxymethyl Cellulose (CMC)

To solve the clumping problem, the researchers coated the iron nanoparticles with carboxymethyl cellulose (CMC), a substance that helps keep the particles separated. This makes the nanoparticles more efficient at cleaning contaminated water.

The CMC coating also prevents the iron particles from rusting. By adding sulphur compounds in conditions without oxygen, the coating forms a protective layer of iron sulphide, making the particles even more effective in cleaning the water.

High Success Rate in Removing Chromium

Tests showed that the S-CMC-nZVI nanomaterial (the improved version with the CMC coating) was able to remove 99% of the harmful chromium, even in different pH levels and with other competing particles in the water. This means the solution is strong enough to work under real-world conditions.

The researchers tested the new material using sand columns and contaminated soils, and it worked very well in immobilizing heavy metals. The next step is to scale up the testing to see how well it works in larger areas.

Potential to Clean Lakes in Bengaluru

This technology could be especially useful in cleaning polluted lakes like Bellandur Lake in Bengaluru, which are contaminated with chromium as well as other heavy metals like cadmium and nickel. It could contribute to a wider effort to clean the environment and protect public health.

The IISc’s development of this special nanomaterial represents a major breakthrough in on-site groundwater remediation, offering a sustainable way to tackle one of the most pressing environmental issues—heavy metal contamination.

About IISc

The Indian Institute of Science (IISc), founded in 1909, is India’s top institute for advanced research in science and technology. Located in Bangalore, it has a long history of producing world-class scientists and researchers. Known globally for its work in engineering and technology, IISc is also home to a beautiful campus, including a historic 150-year-old tree and the Tagore Circle.

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