Synthetic dye is a key barrier for sustainable textile recycling: Tonmoy Saha

Tonmoy’s research interests span textile green coloration, textile functionality, polymer composites, and textile recycling, but his doctoral work centers on developing an advanced color-stripping process, followed by fiber-to-fiber recycling. By targeting reactive dyes used widely in cotton and other cellulose-based textiles, his work aims to produce cleaner, recyclable feedstock suitable for both mechanical and chemical recycling methods.v

“Recycling dyed textile waste is a growing area of focus in sustainable textile management, but it comes with significant technical and economic challenges,” Tonmoy explained. Dyed waste comes from post-industrial sources such as offcuts and production scraps, as well as post-consumer garments. Current recycling approaches—mechanical, chemical, thermal, and upcycling—each have limitations.

Mechanical methods, such as shredding and re-fibering, often reduce fiber quality. Chemical recycling can yield near-virgin quality outputs but is costly and technologically demanding. Thermal recycling provides energy recovery but results in material loss and environmental concerns, while upcycling extends product life without addressing large-scale waste.

The presence of dyes complicates all these methods. Mixed colors hinder sorting, color contamination limits reuse, and many synthetic dyes are engineered to resist removal, creating processing bottlenecks. Moreover, toxic dyes may pose health and environmental risks when released during recycling. 

Tonmoy’s work directly addresses these hurdles. “I am addressing the pressing issue of textile waste by developing an efficient colour-stripping process to remove persistent dyes from cellulose-based fabrics, such as cotton,” he said. “I am trying to produce a suitable feedstock for recycling into new textiles by chemical processes, reducing reliance on raw materials, minimizing waste disposal, and promoting a circular economy.”

A graduate of Aalto University with an M.Sc. (Tech) in Chemical Engineering, Tonmoy completed his master’s thesis under the SUSTAFIT Project before beginning his doctoral journey.  He has conducted his M. Sc. thesis under the supervision of Prof. Ali Tehrani, Head of Textile Chemistry group. His vision is to advance sustainable recycling technologies and help transform textile waste into a valuable resource. 

By refining color-stripping methods, Tonmoy hopes to open new doors in textile recycling, paving the way for more sustainable industry practices. His research stands at the intersection of innovation, environmental responsibility, and practical application—reshaping how the world thinks about discarded fabrics.