Researchers at the Institute of Advanced Study in Science and Technology (IASST) in Guwahati, India, have identified four ionic liquids (ILs) that can extract silk proteins from raw fibres.

The team has discovered an eco-friendly approach that can eliminate the use of toxic chemicals in silk processing, according to a press release from the Department of Science and Technology, Government of India.  

Traditionally, toxic chemicals – such as sodium carbonate, sodium hydroxide, sulfuric acid and lithium bromide – have been used to extract silk proteins fibroin and sericin from various types of raw silk fibres, a key step in the process of making silk from cocoons.

The IASST team, led by Dr Kamatchi Sankaranarayan, published the findings in Chemistry Select by Wiley Publishers, detailing the potential use for sericin extraction from both mulberry (Bombyx mori) and non-mulberry silks, such as Muga (Antheraea assamensis) and Eri (Philosamia ricini), which are both  indigenous to Northeast India.

The IASST team explored six different ILs and found some of them to be particularly effective in removing sericin without damaging the silk protein structure.

The ILs with the best results included 1-Butyl-3-methylimidazolium chloride (BMIM.Cl), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM.BF4), and Tetraethylammonium bromide (TEAB). TEAB appeared to be highly effective