Danish scientists have uncovered a new method that significantly reduces the environmental and social impact of producing blue denim. According to the researchers, this method could reduce the environmental impact of dyeing denim blue by up to 92%, while also preventing exposure of factory workers to harmful chemicals, with only a moderate increase in cost. The research was recently published in Nature Communications.
The production of blue denim is a multi-billion-dollar industry, currently reliant on indigo dye, the only molecule capable of producing denim’s unique shade of blue. This process emits a considerable amount of carbon dioxide, uses a large quantity of toxic chemicals, leading to environmental pollution and harming the health of textile workers and local communities. Indican, an indigo precursor, presents a more eco-friendly alternative for dyeing denim as it doesn’t require toxic chemicals and can directly turn into indigo on the yarn. However, applying this method necessitates technology for the energy-efficient production of indican.
Ditte Welner, Katrine Qvortrup, and colleagues at the Technical University of Denmark engineered an improved version of the enzyme indoxyl glucosyl transferase, found in the indigo-producing plant Isatis tinctoria, capable of economically producing indican on an industrial scale. They also demonstrated economically viable, less harmful dyeing processes that convert indican into indigo to dye denim, one of which utilizes enzymes and a light-driven method.
For the latter, different light sources were shown to aid in dyeing the denim fabric in solution, including energy-saving LEDs, natural sunlight, and even a household light bulb. The light-driven dyeing method is expected to reduce the environmental impact of dyeing denim blue by 73%, while the enzymatic dyeing method could reduce it by 92%. According to market analysis, with an annual transaction volume of 4 billion pairs of jeans, these methods could significantly reduce the production of toxic waste and decrease global annual carbon dioxide emissions by 3.5 million tons.
The researchers suggest that reducing environmental impact could promote the localization of denim production in Western markets, potentially enhancing supply chain transparency and the sustainability of the textile industry.
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