Denim jeans: the one pair of pants that never seems to go out of style. Ever since the mid-20th century, its popularity among people of all ages has only grown, and with it, so has the manufacturing industry. But, as it turns out, creating these pants has a downside: the dye used to turn them blue is polluting the environment.
A team of researchers at the University of Georgia in Athens have recently introduced a new, environmentally friendly dyeing method involving nanocellulose, a substance obtained from plant matter. In the October 21 issue of Green Chemistry, they showed that nanocellulose can significantly decrease the amount of water and chemical consumption during the dyeing process. Not only that, but the procedure itself is a lot simpler than it's always been.
Traditional dyeing uses indigo, a color pigment that is very difficult to dissolve in water. Textile makers must use abrasive chemicals to make indigo water-soluble, then dip the denim in the solution several times for the color to stick. The mixture, which contains toxic chemicals, is then released into the environment, where it causes pollution. According to Smriti Rai, one of the researchers at the University of Georgia, the new dyeing technique avoids this chemical-filled process. "We just mixed [solid] indigo particles with nanocellulose," she shared.
The researchers explained that they dyed the jeans by adding indigo powder to a small amount of nanocellulose. The mixture is just liquid enough to allow them to screen-print it onto the fabric. This method eliminates more than 90% of the water used in the traditional dyeing process. Since it is also very easily absorbed, the workers need only spread the jelly-like mixture onto the fabric once for the color to stick, compared to eight times with traditional dyeing. However, industrial ecologist Robert O. Vos from the University of Southern California warned that manufacturing jeans is still a heavily water-consuming process. He pointed out that most of the water use comes from growing the cotton itself, not dyeing the jeans. So, although the researchers at the University of George have certainly made a groundbreaking discovery, it seems that scientists have yet to figure out how to make jean-manufacturing even more eco-friendly.