The fashion industry is increasing everyday with more and more people worldwide and the demand for new and ever more sophisticated clothes seems inexhaustible.
It is necessary to increase the consumer awareness of the need to make greater use of the articles of society including clothes. We must combine educational pressure on consumers especially about the true cost of waste, with the idea that used clothes are a valuable resource, to increase sustainability.
The production of very large quantities of natural and synthetic materials, and treatment chemicals is getting unsustainable. Efforts are needed to understand the real opportunities for waste valorisation in fashion industry.
The circularity of the fashion industry is a challenge to be faced. The green chemistry and the broader movement to make chemistry and in particular the chemical industry less environmentally harmful focused on the chemical processes that converted raw materials, especially petrochemicals, into more valuable chemicals [1]. The switch to renewable resources such as biomass and the production of safer products are becoming the goal of many research.
In general, the more used products recycled the less the demand for fresh resources. But the more complicated the article the more difficult it will be to get maximum recycle value from it. Complexity is the enemy of circularity.
Have first a look to the numbers: over 70% of the material that is used in clothing ends up in landfill or an incinerator with only 12% recycled; more than 25% of textile fiber is wasted during garment production.
A growing culture to use more recycled fabrics in ‘new’ clothes is arising, but it is not enough. The greatest challenge is sorting the wearable from the non-wearable with the latter still having value through sale back to the producers or recyclers.
But what does it mean recycling the non-wearable? Obviously it depends on the materials. Some examples are discussed.
PET. The polyester in clothes that is labelled as recycled mostly comes from recycled PET bottles and not from used fabrics. This is probably because new clothes use sophisticated blends. The use of solvents to help get around the complexity. This seems logical and necessary, but it adds complexity in the environmental footprint process. Many traditional solvents are being identified as environmentally unacceptable especially those that are now classified as toxic under REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals – Europe normative) assessments [1].
Depolymerisation of PET is one of the most researched technique. It yields monomers suitable for repolymerisation. This is achieved by reacting the PET waste with a reactive small molecule including water and ammonia to produce useful compounds via hydrolysis and aminolysis,respectively. Alcholysis is also popular. The greatest challenge with such processes is the separation and clean-up of the monomer before it can be used in a new polymerization process [1].
Cotton. One of the most commercialized examples of textile recycling is chemical-based and involves the conversion of waste cotton into viscose. Cotton is depolymerized into a pulp that is then turned into viscose in a process similar to that made from wood pulp. On the other hand when the quality of the waste textile is insufficient for reuse, it can be blended with virgin cotton [1].
Over the last decade, studies have been conducted on anaerobic digestion using cotton waste to produce methane-rich biogas.
Furthermore, composting seems to be an alternative solution for cotton textile plants, where waste not suitable for clothes are difficult to recycle [2].
Upstream of any cotton waste valorisation project, the clean-up of the waste will require effort. In fact many clothes contain both cotton and other materials such as polyesters. This fundamental separation challenge is probably best met with modern green solvent technology typically involving the preferential dissolution of the polyester using for example, an ester solvent [1].
Textile waste for other industries. Textile waste represents a source of raw materials for typical application in construction, such as insulation materials for noise and temperature and fillers or reinforcements of concrete [2].
In conclusion it can be said that the relevant greening goals in fashion industry concern the textiles and the additives. Natural fabric treatments may not have changed over many years and can be a source of environmental problems including the use of dangerous chemicals and the production of hazardous waste. On the other hand, greener methods for reactions and alternative renewable chemical starting materials are needed, for synthetic textiles.
More substantial improvements would involve replacing synthetic additives with natural ones and indeed, avoiding additives all together where possible [1].
The complexity of modern fabrics including the use or multiple materials and many chemical treatments makes their conversion into the more valuable chemicals more difficult and the simplification of upstream processing will really help their valorisation at end-of-life. This can be combined with lower environmental footprint chemical treatments such as the use of greener solvents and the avoidance of hazardous chemicals. All these scientific efforts can be combined with social efforts in developing reuse practices such as the second-hand clothes market.
[1] Using green chemistry to progress a circular fashion industry – James H. Clark; Current opinion in green and sustainable chemistry, Vol 38, December 2022.
[2] A Review on Textile Recycling Practices and Challenges – Jeanger P. Juanga-Labayen , Ildefonso V. Labayen, Qiuyan Yuan; Textiles 2022, 2(1), 174-188.
