IIT Madras & Tel Aviv University Researchers develop effective Aerogel-adsorbents to remove trace contaminants from wastewater

CHENNAI : Researchers from Indian Institute of Technology Madras (IIT Madras) and Tel Aviv University, Israel, have developed an aerogel adsorbent that can remove trace pollutants from wastewater.

This graphene-modified silica aerogel removes over 76 per cent of trace pollutants (PPM level) in continuous flow conditions, offering a sustainable path for large-scale water purification. The research team is dedicated to enhancing these results for large-scale applications.

Aerogels, which are incredibly lightweight solids composed mostly of air, are excellent adsorbents (a solid substance used to remove contaminants). In addition, they offer advantages like adjustable surface chemistry, low density, and a highly porous structure. These materials, often referred to as ‘solid air’ or ‘frozen smoke’, can be easily fabricated.

India, facing the challenge of supporting 18 per cent of the world’s population with just 4 per cent of global water resources, has intensified efforts to address water pollution, particularly in water-intensive industries like pharmaceuticals and textiles. The textile sector alone discharges nearly ten lakh tons of toxic synthetic dyes annually, posing severe threats to aquatic life and ecosystems.

The research was led by Shanti Swarup Bhatnagar Prize Awardee Prof. Rajnish Kumar from IIT Madras and included Mr Subhash Kumar Sharma and P. Ranjani, Research Scholars, Department of Chemical Engineering, IIT Madras and Prof. Hadas Mamane, School of Mechanical Engineering, Tel Aviv University, Israel.

The findings were recently published as a paper in the prestigious journal Nature Scientific Reports (https://doi.org/10.1038/s41598-023-43613-w).

Elaborating on the need for such research, Prof. Rajnish Kumar, Department of Chemical Engineering, IIT Madras, said, “Indigenous techniques for wastewater purification have become essential not only to combat pollution but also to preserve water quality, protect ecosystems and mitigate health risks associated with contaminated water.”

Prof. Rajnish Kumar added, “Conventional wastewater treatment methods struggle to remove trace of pollutants, especially pharmaceuticals. In response, scientists have explored various methods, including adsorption, advanced oxidation processes and membrane filtration. Among these, adsorption is attractive because of its eco-friendly nature, cost-effectiveness, and efficient pollutant removal capabilities.”

Subhash Kumar Sharma said, “I am genuinely enthusiastic about the transformative potential of our research in mitigating water pollution challenges. Our GO-SA adsorbent represents a remarkable step towards sustainable water purification. Our commitment to scientific excellence and environmental responsibility drives us.

Speaking about the technical aspects of this research, Prof. Hadas Mamane, School of Mechanical Engineering, Tel Aviv University, Israel, said, “This jointly developed GO-SA aerogels can be customized to target specific contaminants by modifying their surface chemistry, making them versatile. Furthermore, they can be regenerated and reused multiple times, reducing waste and operational costs, making them a sustainable solution for water purification.”

This research team developed a silica aerogel modified with graphene (a Nobel-winning form of carbon renowned for its exceptional properties). The researchers employed a method called ‘supercritical fluid deposition’ to prepare these modified aerogels and rigorously studied their effectiveness.

The Graphene-doped modified silica aerogels (GO-SA) were found to exhibit remarkable efficiency in purifying water, attracting and removing contaminants due to graphene’s unique molecular structure which further enhances the available surface area of the aerogel. Under real-life conditions mimicked in their experiments, the material removed over 85% of pollutants in controlled settings and more than 76% in continuous flow conditions.