IIT Delhi team develops cotton fabric that can adsorb air pollutants

September 08, 2021 - India

A team at the Indian Institute of Technology Delhi (IIT-D) has developed a modified cotton fabric capable of adsorbing harmful air pollutants from air. ZIF-8@CM cotton and ZIF-67@CM cotton, as these are called, are zeolite imidazolate framework (ZIF)-modified functionalised fabrics that adsorb high levels of organic air pollutants like benzene, aniline and styrene from air.

The team is led by Ashwini K. Agrawal and Manjeet Jassal at the SMITA Research Lab in the department of textile and fibre engineering, and Saswata Bhattacharya in the department of physics, an IIT-D press release said.

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 Hardeep Singh, who carried out detailed experiments to develop these fabrics, porous materials like 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 anti-microbial, biomedical, particulate matter-filtering, fuel-filtering, chemical warfare-protecting and UV radiation-absorbing properties. The ZIFs specifically are more suitable under Indian conditions, Singh said.

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 developed a low-cost cotton fabric, which is capable of adsorbing 400-600 per cent more VOCs than ordinary cotton fabrics.

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

The ZIF-8 functionalised 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 degrees Celsius 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) and Resil Chemicals Pvt Ltd., Bangalore under the Nanomission.