New Delhi: An IIT Delhi research team led by Prof. Ashwini K. Agrawal and Prof. Manjeet Jassal at the SMITA Research Lab in the Department of Textile and Fibre Engineering, and Prof. Saswata Bhattacharya at the Department of Physics has developed a modified cotton fabric capable of adsorbing harmful air pollutants from air.

ZIF-8@CM Cotton and ZIF-67@CM Cotton, as they are called, are Zeolite Imidazolate Framework (ZIF)-modified functionalized fabrics, which adsorb high levels of organic air pollutants like benzene, aniline, and styrene from the ambient air.

Air pollution resulting from the rising levels of particulate matter, nitrous oxides, sulfur oxides, carbon oxides, and other toxic volatile organic compounds (VOCs) is a major concern. A long-term exposure to even a few parts per million of these chemicals takes a toll on health and can cause asthma, eye, and throat irritations etc.

According to research scholar, Mr. Hardeep Singh, who carried out detailed experiments to develop these fabrics, porous materials such as activated carbon, zeolites, and Metal Organic Frameworks (MOFs) are capable of adsorbing VOCs from air. The MOFs can be tweaked to create textiles that have antimicrobial, biomedical, particulate matter filtering, fuel filtering, chemical warfare protecting and UV radiation absorbing properties. The ZIFs specifically are more suitable under Indian conditions.

Using a technique known as in-situ growth of ZIF-8 and ZIF-67 nanocrystals on the carboxymethylated cotton fabric using a rapid water-based textile finishing approach, the researchers at IIT Delhi have successfully developed a low-cost cotton fabric, which is capable of adsorbing 400-600% more VOCs than ordinary cotton fabrics.

Furthermore, these fabrics are robust and can withstand even the harsh conditions of washing. They can be used repeatedly and in designing functional filters and pollution controlling upholstery fabrics among others.

Speaking of the modified cotton fabric, which is capable of adsorbing harmful air pollutants from the air, Prof. Ashwini Agrawal, Textile and Fibre Engineering Department, IIT Delhi said, “In this study, we have shown the functionalization of cotton fabric by ZIF MOFs (ZIF-8 and ZIF-67) using a rapid, facile, eco-friendly, and scalable approach. The ZIF functionalized textiles possess a huge potential for applications as protective garments and in controlling indoor air pollution. These fabrics may be used as upholstery for controlling gaseous pollutants that cannot be filtered out using a filter media. In particular, these can be used within closed spaces, such as homes, offices, theatres, aeroplanes, and other transport vehicles.”

The ZIF-8 functionalized fabric was found to adsorb a maximum of 19.89 mg/g of aniline, 24.88 mg/g of benzene, and 11.16 mg/g of styrene on the weight of the fabric. These fabrics could be easily regenerated by heating the fabrics at 120 °C and reused without any decrease in their adsorption capacity for several cycles.

The research was jointly funded by the Department of Science and Technology (DST), GoI and Resil Chemicals Pvt Ltd., Bangalore under the Nanomission.

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