The textile industry is currently seen as being the world’s most polluting industry. It experiences significant challenges to become greener and more sustainable.
“The fashion industry produces 20 per cent of global wastewater and 10 per cent of global carbon emissions - more than all international flights and maritime shipping combined. Textile dyeing is the second largest polluter of water globally. It takes about 2,000 gallons of water to make a typical pair of jeans.”1
The textile industry is looked upon as one that is positively affecting global economic development. The largest and most important exporter of textiles is China, followed by the European Union, India and the USA2. However, textile factories face several challenges and the the largest one is disposition of difficult to degrade effluent streams coming particularly from dyestuff manufacture.
Initiatives to increase the sustainability of the textile industry are being led by certifying organisations like OEKO-TEX®, GOTS and Bluesign. OEKO-TEX® for example is continuously in development of test methods and setting limit values for the textile and leather industry, providing boosts for innovation and making a significant contribution to the development of high-quality products. Their mission is to generate trust in the textiles and leather industry in their production, and to support the path to a sustainable future.
Both dry and wet processing are utilised for fibre production in textile factories. A considerable quantity of potable water is consumed in the wet process and it generates highly contaminated wastewater also in large quantities.
The fibre production process consists of sizing, de-sizing, sourcing, bleaching, mercerising, dyeing, printing and finishing3,4. Figure 1 shows the main pollutants in the wastewater discharge from each step5.
The dyeing process is an important step in textile manufacturing. During this stage, colour is applied to the fibre, and several chemicals may be used to improve the adsorption process between colour and fibre. When the final product is ready following the finishing process, remnants of these dyes and chemicals become part of the effluent6.
Improvement in the dyeing process requires other chemical reagents known as auxiliaries or additives. These compounds increase the quality of the final product and improve silkiness, texture, light resistance, stability and other desirable qualities. Surfactants, dispersants, salts and other additives are typically used. These additives are not considered in most of the chemical treatments of wastewaters.
The estimated world-wide use of naphthalene sulfonate as a concrete admixture and as a dye dispersant is about 300 000 ton/year, which is equivalent to 2500 blue whales of 120 ton each7 Liquid dyes are aqueous dispersions typically stabilised with naphthalene sulphonates8,9. This petroleum or coal-based chemical is a well studied pollutant due to its widespread occurrence in the environment and for its potential hazard to human and wildlife health10,11.
Borregaard’s lignin bio-based dispersants offer significant benefits for the formulation of textile dyes, providing for sustainable and environmentally friendly use. Based on results for extensive and substantial testing, Borregaard’s lignin bio-based products are judged to be safe to life. They have a Lethal Concentration (LC50) rating for fish of >2.400 mg/l12. Sulfonated naphthalene condensate has a rating of LC50 between 100 - 500 mg/l putting it in the risk zone for survival of fish.
Utilised in the manufacture of disperse, acid, reactive and vat dyes for colouring polyester, cotton, wool and viscose, Borregaard’s line of dyestuff dispersants offer significant environmental benefits given their benign impact on nature and their long-term sustainability profile. Borregaard’s lignin-based formulation aids are exempt from Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) certification as they are bio-based polymers unlike naphtalene13. In the environment, they degrade/decompose in the same time frame as the trees from which they originate. According to our best knowledge, Borregaard’s bio-based lignin products comply with the limits for restricted substances listed by Bluesign (Version8.0, July 01 2017)* & of Standard 100 by OEKO-TEX® (edition 03.2019).
Utilising Borregaard’s bio-based products in textile dyes contributes towards making the textile industry a more sustainable and environmentally friendly one.
References:
*The bluesign® Restricted Substances List (RCL) specifies restrictions (limits and bans) for chemical substances in articles made of textile and leather, and accessories for textile and leather articles. No substance listed on the bluesign RCL is intentionally added to Borregaard lignins. All substances on this list are not regularly monitored during the manufacture of our products. According to our general knowledge about lignosulfonates it is very unlikely that these substances are formed during production or are contained at significant levels in our raw materials.
