Page 135 - CW E-Magazine (17-9-2024)

Point of View

Some initiatives for a more sustainable textiles industry

Textiles are ubiquitous. They are used as apparel, in our
homes and in furniture, and also in products such as medical Forecast of global fi ber demand
and protective equipment, buildings and vehicles. They serve Million tons
aesthetic and comfort purposes, in addition to being functional
products with, at times, stringent performance requirements. +2-3%
No surprise then that demand and supply of textiles continues to 142
grow in all parts of the world – albeit to varying extents. Much +1% 127
of the growth is in the developing world, wherein textiles play 113 113
a more basic role of clothing. 99

Sizeable environmental impacts
Global textiles production almost doubled between 2000
and 2015 and is expected to reach 142-mt by 2030, from
about 118-mt now, according to estimates by Lenzing, a
leading producer of viscose fibre. The environmental impacts
this creates – in water & energy consumption, effluent
generation in the many stages of processing including from
fibre to fabric, and land use (relevant for natural fibres) is
substantial. To cite just one impact, the industry releases 2019 20 21 25F 2030F
1.7-mt of carbon dioxide annually – roughly 10% of global emissions. There is also a humungous textile waste issue – every
second somewhere in the world a truckload of textiles is landfilled or (worse) incinerated.

The greatest environmental impacts occur in the several process steps that transform fibres to yarn and eventually textile materials.
The range of processes include sizing & desizing, scouring, bleaching, mercerisation, dyeing & printing, and finishing. Each requires several
chemicals, some of which are added on in one stage and removed in another. Dyeing, for example, releases reducing agents, dyes, soap,
mordants, acids, metal salts, surfactants, etc. in wastewaters, leading to effluents with high chemical/biological oxygen demand, pH, total
solids, and colour. Additional chemicals are often added to yarns or fabrics to provide performance attributes including water repellence,
stain resistance, flame resistance, moisture wicking, wrinkle resistance, antibacterial and odour resistance properties. The safety and
environmental impacts of many of these chemicals are also being reassessed in the wake of new scientific evidence.

Here are some trends are can resetting the industry on a more sustainable growth path.

Sustainable dyeing
Textile dyeing is amongst the most polluting stages of textile processing, using copious quantities of water, and a multitude of chemicals
many of which end up in the effluent and need to be treated prior to discharge. Anywhere from 10-50% of the colorants used is wasted in
the process and represents a sizeable economic loss besides an environmental burden. Going natural is not really an option given the limited
amounts in which most natural dyes (which are often extracts of plants or even animals) are commercially available, and their relatively
poor affinity to fabrics, which needs to be compensated through complex chemistries that impose their own burdens on the process.

Innovations from some of the leading colorant manufacturers are addressing some of these challenges. Today there are many suppliers
that have launched more sustainable product lines: Archroma (Earthcolors), Huntsman (Avitera), Garmon (Nimbus) and DyStar (Cadira
and Lava). Denim dyeing, a notoriously polluting process, for example, has been cleaned up significantly, using aniline-free chemistry;
reactive dyes have been developed that enable water and energy savings of the order of 50%; and microbially produced dyes with robust
fastness properties (at small scale) have been developed using fewer chemical inputs and reduced water requirements.

Process and machinery innovations are also enabling dyeing with a fraction of water and energy compared to regular methods. Switching
to waterless processes are enabling use of new chemistries, which can be optimized to minimize use of chemicals of concern. Using
supercritical carbon dioxide as solvent in dyeing is eliminating the need for water and other potentially harmful chlorinated solvents and
can be relatively easily cleaned and re-used by letting it go into gas phase and then recompressing it.

Chemical Weekly September 17, 2024 135

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