Hi everyone! In last week’s post, Dyes and Our Dying Earth Part 1, I looked at the environmental impacts of dyes. In this post, I will discuss some of the alternatives and technological innovations in the industry to ensure that dyes can be more sustainable.
Biogenic/natural/bio-based dyes
Most of the dyes in our clothes today are synthetic dyes, biogenic/natural/bio-based dyes are used as alternatives. Natural dyes can be extracted from plants, waste or by-products from agriculture and food waste such as berries, skins and shells) (Elsahida et al., 2019). The use of wastes in natural dye production presents an opportunity to progress towards a circular economy approach in the textile and fashion industry. For example, wastes from the production of natural dyes include biomass waste after extraction which can be reused into derivative products such as biogas and animal feed, thus closing the loop.
Floral dyes
Some examples of natural dyes are those that are extracted from flowers. In a study that looked at the use of floral dyes, four different varieties were used (C. cristata, L. camara, R. damascena and T. erecta) (Pervaiz et al., 2016). Before extraction of natural dyes, several processes need to be considered – material preparation, solvents used and extraction methods. For floral dyes, petals from the flowers are rinsed to remove dirt and impurities before they are diluted in water and left to soak at room temperature for 3 days. The resulting mixture is then filtered to remove any remaining impurities. The study found that these floral dyes are suitable to dye leather needed in Punjab’s thriving leather industry (Pervaiz et al., 2016).
Challenges
However, significant challenges remain in implementing these alternative dyes into the textile or fashion supply chain. Firstly, natural dyes have a limited colour range (yellow, orange, red, blue, purple, but hardly any green) compared to synthetic dyes that can produce colours of almost any hue (Fried et al., 2022). As such, semi-synthetic approaches are sometimes used to obtain the desired colours. Secondly, downstream processing of natural dyes is a complex procedure and isolating the dyes from fermentation media and biomass is still a big challenge. Thirdly, the properties of biogenic or natural dyes may hinder widespread application – they may present bioactive properties such as antimicrobial and cytotoxic effects. These are among the 2 most concerning bioactive properties as the large-scale application of antimicrobial substances in textile dyes may go against efforts to ensure the effectiveness of microbial drugs (Fried et al., 2022). Lastly, mordants are often used in the dyeing process for natural dyes, a substance that helps to bind the colours to the fabric and makes the colour more resistant to washing and UV light (Elsahida et al., 2019). Ironically, the production of environmental-friendly dyes also has impacts on the environment – mordant contains heavy metals and where high concentrations of mordant are needed to ensure good quality dye production, its use can be toxic to both human health and the environment.
Nonetheless, while there are still challenges in wide-scale implementation, advances in biotechnology have offered some solutions to increase the reliability of alternative dyes and improve molecular engineering processes. Until then, let’s keep running away from fast fashion.
Cheers,
Chermaine
References
Elsahida, K., Fauzi, A. M., Sailah, I., & Siregar, I. Z. (2019). Sustainability of the use of natural dyes in the textile industry. IOP Conference Series: Earth and Environmental Science, 399(1), 012065. https://doi.org/10.1088/1755-1315/399/1/012065
Fried, R., Oprea, I., Fleck, K., & Rudroff, F. (2022). Biogenic colourants in the textile industry – a promising and sustainable alternative to synthetic dyes. Green Chemistry, 24(1), 13–35. https://doi.org/10.1039/D1GC02968A
Pervaiz, S., Mughal, T. A., Khan, F. Z., & Najeebullah, M. (2016). Floral Dyes: An Opportunity for Punjab Leather Industry to Promote Sustainable Fashion Development. 8, 7.