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It is difficult to identify an area of our lives where textiles don’t exist. From the clothing on our bodies to medical bandages, from fabrics integrated into homes and surroundings, textiles play vital functional roles to improve our everyday.
Most of us think the cost of our clothes can be calculated by how much we paid in the shop. However, there is a hefty price behind each piece that goes largely unnoticed: the cost to the environment.
While essential, the garment industry contributes colossal global carbon emissions because of its enormous, ongoing production volume. According to figures from the United Nations Environment Programme (UNEP), it takes 3,781 liters of water to make a pair of jeans – equal to 33.4 kilograms of carbon emission. [1]
Now think of the big picture.
Every year the fashion industry uses 93 billion m3 of water [2]. Moreover, around 20% of wastewater worldwide comes from the apparel industry, mainly fabric dyeing and fabric treatment. Textiles effluent is highly variable in composition due to textile mills using upwards of 20,000 different chemicals to make clothes – many of them jeopardizing public health [2].
No doubt, if today’s lifestyle patterns continue, global consumption of apparel will keep growing (predicted to rise from 62 million MT in 2019 to 102 million MT by 2029) [2].
The question now is, “How can textile producers keep up with exponential global demand without inflicting exponential harm to the environment?”
There are 3 ways Chitosan can help:
NUMBER ONE: As a dyeing agent to bind the dye to clothes (instead of salt)
When cellulosic fibers (cotton, linen, hemp, viscose) are immersed in water to be dyed, the cellulosic fiber generates negative charges on the fabric’s surface (called the Zeta Potential) [4] Since Reactive Dyes also have a negative charge, Salt is deposited in the water as an Exhausting Agent to create a positive charge and attract the dye into the cloth.
However, the dye percentage that permanently bonds into the fiber (fixation rate) is weak – the average fixation rate for cotton being 75% [5]. Removing the leftover ‘unreacted’ dye is incredibly difficult as it is still ‘glued’ onto the fabric by salt. Vast amounts of water are required to dilute and ‘loosen’ the salt concentrations. Altogether, the discharge of untreated effluents (dye, salt, wastewater) creates environmental threats, including devastating the aesthetic of water bodies, increasing Biochemical and Chemical Oxygen demand (BOD and COD), impairing photosynthesis by preventing light penetration through water, and inhibiting plant growth. Human health is compromised as environmental pollutants enter the food chain [6].
The SOLUTION: Instead of salt, mill owners can use Chitosan to bind dyes to the fabric.
Since Chitosan is a cationic polymer, Chitosan is an eco-friendly alternative from salt for dyeing. Not only is salt-free dyeing (or salt reduction) possible, but pre-treating the fabric with Chitosan can help boost dye uptake and achieve uniform dyeing [7]. This is due to Chitosan cationizing the cellulosic fabric surface and decreasing the anionic dyes’ repulsion force – resulting in an even film on the surface.
NUMBER TWO: As an eco-friendly wastewater treatment
Although many wastewater treatment methods exist [8], their efficiency is not yet optimized as waste still escapes untreated – demonstrated by this industry’s steep waste statistics. On top of this, the use of chemical wastewater treatments is undesirable as contaminations may remain (“Take out the bad only to leave different bad stuff behind”).
But think of the above mechanism where Chitosan’s cationic charge attracts dye’s anionic charge and transfer this relationship out to the effluent. The combination of Chitosan’s eco-friendliness, positive charge, and polymer structure equate to strong potential for Chitosan as a bio-adsorbent, bio-coagulant, and bio-flocculant.
As a polymer, it is efficient at binding and linking particles to itself [9]. And with most pollution colloids being negatively charged, Chitosan can form larger, more settled flocs without creating secondary pollutants [10].
NUMBER THREE: Treat fabrics with Chitosan to achieve functional textile properties, especially Antimicrobial
To improve aesthetic, comfort and meet end-user demands, fabrics are given functional finishes (antimicrobial, antistatic, antiwrinkle, etc.) With concerns that the finishes are achieved via chemicals, there is demand for greener, multifunctional materials.
This is where Chitosan’s characteristics of being biocompatible, biodegradable, and antimicrobial enable textile mills a solution away from traditional chemicals. Outside of forming Chitosan fibers, Chitosan applications for textile modifications currently include antimicrobial finishing, antistatic finishing, and deodorizing finishing [11].
Antibacterial treatment textiles are not only essential in health industries and hospitals but in all households where textiles provide surfaces for microorganisms to latch on, transmit diseases, and threaten our health – especially in light of COVID-19.
In response, Chitosan’s cationic nature (as explained in previous BioPolymers article https://www.vnfoods.vn/news/the-3bs-biofriendly-biodegradable-anti-bacterial) can change the membrane of harmful anionic bacteria, restrict growth nutrients, and ultimately prevent bacterial metabolism.
But while Chitosan offers a biofriendly antibacterial agent, we realize that a single antimicrobial agent will have limitations against the expansive range of bacteria that exist. Thus, we believe combining Chitosan with other antimicrobial components can broaden antimicrobial protection and are always open to collaborations.
In conclusion (like the global plastic problem), the textile industry’s overreliance on chemicals and immense pollution won’t be solved overnight by one company or material. But VNF’s Chitosan can step up to play a big part: to bind the dye to fabric (reducing salt overuse), as a biofriendly flocculant, coagulant, and adsorbent to treat wastewater, and to achieve functional fabric finishes.
Born from overlooked shrimp shells, VNF’s Chitosan offers eco-friendly solutions to empower the textiles industry to sustain its growth by reducing its future pollution footprint.
REFERENCE
[1] Cleaning up couture: what’s in your jeans?. Retrieved 8 April 2021, from https://www.unep.org/news-and-stories/story/cleaning-couture-whats-your-jeans
[2] How Much Do Our Wardrobes Cost to the Environment?. Retrieved 8 April 2021, from https://www.worldbank.org/en/news/feature/2019/09/23/costo-moda-medio-ambiente#:~:text=Every%20year%20the%20fashion%20industry,disposed%20of%20in%20a%20landfill.
[4] Patil A., Maiti S., Mallick A., Kulkarni K., Adivarekar R. (2020) Cationization as Tool for Functionalization of Cotton. In: Shahid M., Adivarekar R. (eds) Advances in Functional Finishing of Textiles. Textile Science and Clothing Technology. Springer, Singapore. https://doi.org/10.1007/978-981-15-3669-4_13
[5] Bomgardner, M. (2018). These new textile dyeing methods could make fashion more sustainable. CHEMICAL & ENGINEERING NEWS, (29). Retrieved from https://cen.acs.org/business/consumer-products/new-textile-dyeing-methods-make/96/i29
[6] Lellis, B., Fávaro-Polonio, C., Pamphile, J., & Polonio, J. (2019). Effects of textile dyes on health and the environment and bioremediation potential of living organisms. Biotechnology Research And Innovation, 3(2), 275-290. DOI: 10.1016/j.biori.2019.09.001
[7] M.A. Rahman Bhuiya, Abu Shai, M. A. Khan (2014). Cationization of Cotton Fiber by Chitosan and Its Dyeing with Reactive Dye without Salt. Chemical and Materials Engineering, 2(4), 96 – 100. DOI: 10.13189/cme.2014.020402.
[8] Hossain AKMNU, Sela SK, Saha S, et al. Treatment of textile wastewater using natural catalyst (chitosan and microorganism). J Textile Eng Fashion Technol. 2018;4(5):320-325. DOI: 10.15406/jteft.2018.04.00159
[9] Ishak, S., Murshed, M., Md Akil, H., Ismail, N., Md Rasib, S., & Al-Gheethi, A. (2020). The Application of Modified Natural Polymers in Toxicant Dye Compounds Wastewater: A Review. Water, 12(7), 2032. DOI: 10.3390/w12072032
[10] Nechita, P. (2017). Applications of Chitosan in Wastewater Treatment. In E. Shalaby, Biological Activities and Application of Marine Polysaccharides. Retrieved from https://www.intechopen.com/books/biological-activities-and-application-of-marine-polysaccharides
[11] Rohani, A., Bashari, A., & Shakeri, M. (2018). Recent advances in application of chitosan and its derivatives in functional finishing of textiles. In The Impact and Prospects of Green Chemistry for Textile Technology (1st ed., pp. 107-133). Woodhead Publishing. Retrieved from https://www.researchgate.net/publication/330053777_Recent_advances_in_application_of_chitosan_and_its_derivatives_in_functional_finishing_of_textiles