Part 3: Green Chemistry Applied to Textiles
By J. Michael Quante, AATCC Staff
Over the last two decades, the textile industry has been involved in green chemistry research and applications to improve the industry’s reputation by using materials and processes more conducive to environmental protection and human health. These efforts are balanced by the need for economically viable production capabilities to help the industry stay competitive. But the history of some treatments go way back in time. Here are three areas where green chemistry was applied to some of textile sciences’ thorniest problems.
Enzymes: A Gift from Nature
Enzymatic textile treatments have been on the textile stage for centuries. As Ian Hardin, 2010 AATCC Olney Award Medalist, pointed out in his Olney Address, the retting of flax was done by exposing the plants to soil microorganisms and their enzymes. An early major breakthrough in green chemistry applied to textile technology occurred in 1917, when amylase was first used in desizing fabrics, primarily cotton, after weaving. Since then, enzymes, including amylases (for desizing), cellulases (for biopolishing), pectinases (for bioscouring), and others, have provided a major arsenal for industrial textile manufacturing applications. Active research is underway to genetically engineer enzymes that are even more effective and selective, potentially minimizing treatment time, cost, and unintentional damage to fabrics.1
Dyeing and Finishing: More with Less
Traditional dyeing methods are often inefficient, require large amounts of water and chemical auxiliaries, and result in significant wastewater pollution. Application of green chemistry principles is making headway in addressing these issues. In one example, R. S. Blackburn at the University of Leeds replaced toxic sodium sulfide with reducing sugars for C.I. Sulfur Black 1 dyeing.
Recently, Yunsang Kim and his team, at the University of Georgia, Athens, GA, USA, won first prize in the first international Green and Sustainable Chemistry Challenge for their work using nanocellulose to improve dyeing efficiency. Kim’s process significantly minimized wastewater dye and auxiliary chemical pollution from the dyeing process.
So called “waterless” dyeing methods are also becoming more prevalent, especially for polyester fabrics. One process uses supercritical CO2 to transfer dye to many types of synthetic fabrics. Another involves cotton pretreatment. Significant issues, such as adoption by industry due to the high cost of these technologies, remain to be addressed.
Fibers: Back to the Earth
Creating or modifying fibers that are biodegradable or are sustainably recyclable is another useful application of green chemistry.
Two well-known major manufacturers of these new generation biodegradable fibers, Lenzing and NatureWorks, are makers of Tencel (lyocell) and Ingeo (polylactic acid) fibers, respectively. These fibers have been publicly available for many years now and use waste plant feedstocks.
One pioneering research team that won the 2015 Presidential Green Chemistry challenge found a new way to dissolve and use cellulose in biodegradable materials, including textiles. Robin Rodgers and his group at the University of Alabama have discovered that a non-toxic ionic liquid allows cellulose to be modified in ways that can adjust its properties to suit the need. Initial applications will be in the automotive industry. Importantly, this technology makes greater use of waste plant material as a substitute for petroleum-based feedstocks.
A potentially marketable fiber under active investigation is poly(hydroxyalkanoates) or PHAs, which are biodegradable polyesters that can be produced through bacterial fermentation. PHAs are currently used in packaging materials, bioplastics, and the fibers are used in fiber blends. The issue with PHA fibers are not so much production capacity. PHAs are subject to thermal instability, are brittle, age poorly, and are expensive.2 Therefore, continued research is needed if PAHs are to become another useful fiber in the textile technology tool box.
In Part 4 of the series, we will discuss the present and future of green chemistry in textiles with industry leaders. Hope you’ll join us then.
- Araujo, R.; Casal, M.; Cavaco-Paulo, A. Design and Engineering of Novel Enzymes for Textile Applications. In Advances in Textile Biotechnology; Nierstrasz, V.A., Cavaco-Paulo, A., Eds.; Woodhead Publishing Ltd.: Cambridge, UK, 2010; pp 3–31.
- Chokak, I.; Blackburn, R. S. Sustainable Synthetic Fibers: the Case of Poly(hydroxyalkanoates) (PHA) and Other Fibers. In Sustainable Textiles: Life Cycle and Environmental Impact; Blackburn, R. S., Ed.; Woodhead Publishing Ltd.: Cambridge, UK, 2009; pp 88–112.
Opinions expressed in this blog post are those of the author and not necessarily those of AATCC.