How natural dyes in the textile industry are compatible with eco -innovation?

Fanny Coury International Professional Master in Management of Eco-Innovation 2011-2012 Module M2: Science & Technology Evaluation INDIVIDUAL ESSAY How natural dyes in the textile industry are compatible with eco -innovation? EXECUTIVE SUMMARY The objectives of this paper are to understand the characteristics and differences of synthetic and natural dyes used in the dyeing process in the textile industry as well as the innovations and new potential in this field. This will help us define if natural colorants comply with the principles of ecoinnovation and if they can be considered as an alternative to synthetic colorants. There is a tendency to say that natural dyes will not be a replacement of synthetic dyes because of too many economical, technical and even environmental drawbacks as well as a problem of land use efficiency. On the other hand, becoming a complement to some chemical dyes is a possible way for natural colorants according to companies such as TDV Industries and Couleurs de Plantes in France and the conclusions from research projects conducted in Austria. The potential of natural dyes is for now reduced to artisanal processes and small companies that are specialized on a niche. But thanks to innovation and combination of synthetic and natural dyes, more efficiency in terms of performances and reduction of pollution will be achieved in the future considering the ecological trend of today. KEY WORDS Natural dyes, synthetic, textile industry, mordants, toxicity, light fastness Introduction Since the discovery of entirely synthetic dyes in the middle of the nineteen s century (1856) by Perkins, more and more concern were raised about the consequences of water pollution through wastewater and health issues as results of the dyeing textile industry processes. There was a renewed interest for natural dyes and the idea that they could become an alternative to synthetic dyes was therefore suggested. Nevertheless, the use of natural dyes is not easy to implement on an industrial level and also according to eco-innovation criteria such as the integration of environment, society and economy according to sustainable development principles. In order to meet those criteria, many research groups and companies tried to understand them and find new ways to integrate eco-dyeing processes in textile for this field to become more sustainable by reducing the use of chemicals and synthetic substances. The question is now are natural dyes an alternative to synthetic dyes in the textile industry? And if yes, how? Materials and Methods The conclusions of this essay come from a synthesis of readings of scientific articles on natural dyes, but also on two interviews performed on the phone and via email exchange with TDV Industries and Couleurs de Plantes through information crossing and the use of advantages/ disadvantages method. Results and discussions Econoving, 18 November 2011 Page 1

Why are natural dyes now (re)considered in the textile industry? Textile manufacturing is a very old industry and has experienced many changes and evolutions since the first crafted fabric by humans. One field of constant developments and innovations is the dyeing process of dyes which is the main focus of this paper in trying to answer the following questions: are natural dyes an alternative to synthetic dyes and if yes, how are they compatible with ecoinnovation? The notion of eco-innovation could be defined as a sustainable use of natural resources to respond to people s need with respect of the carrying capacity of the earth, by maintaining equality between people and at the same time fostering economic growth. This subject is relevant because it has been shown that the use of synthetic dyes in the textile industry has negative impacts on the environment and also on human s health and so is now an important issue. Indeed, the wastewater coming from textile and tannery industries are considered as highly toxic because of several heavy metals, salts and dyes that can disrupt the ecosystems in particular in aquatic ecosystems and cause health problems. (Tigini V et al., 2010). Some types of dyes called Azo dyes are even composed of cancercausing chemicals that can affect humans and salts used in the reactive dyeing of cotton lead to salinization of local and agricultural water in developing countries like India because western production facilities were shifted there in order to avoid European laws (Steinberger J et al., 2009). Mentioning regulations issues, more and more synthetic dyes become the target of stricter legislations in order to lessen the negative impacts on the environment, on health and also comply with broader legislations on the ecosystems at country or European levels like the REACH regulation (European Community Regulation on chemicals and their safe use). Eco-toxicity tests becoming more frequent and required, their cost become a threat to the dyeing industry using only synthetic components. This is one of the reasons that have given more consideration to natural dyes for the textile industry. (Hancock M & Boxworth A, 1997). Another concern will be the fact that synthetic dyes are products of the petroleum industry and being aware of the increase in oil prices and scarcity of the fossil fuel resources, thinking about alternatives to those types of dyes is more than appropriate. This is another reason which natural dyes are potential solutions to the use of synthetic dyes. Finally, the rising concern about environmental protection that reaches people, consumers, politics and industries put more and more pressure on polluting production processes and push towards new developments and ecoinnovation. What are natural dyes? A dye is a colored substance used in different industries such as textile, plastics, food...natural dyes are dyes or colorants derived from animals, plants or minerals without any synthetic chemical treatment. The most common ones are extracted from the following plants (Hancock M & Boxworth A, 1997): - Madder for yellow - Cutch for brown - Cochineal for fushia - Weld for yellow - Indigo for blue Natural dyes were used in the past to color fabrics using artisanal extraction and dyeing processes but those methods were time consuming and usually needed high quantities of energy mainly water and heat. Moreover, the production was not done on a high frequency and was performed for low Econoving, 18 November 2011 Page 2

quantities of products because of a local demand according to seasons. Those criteria were not suitable anymore during the industrial revolution and especially when entering into a consumptiondriven society and the potential of natural dyes for industrial use is therefore uncertain. In order to understand the different types of dyes, their use in textile, we will briefly have a look at the textile industry and its evolutions. Textile industry and its evolutions toward synthetic dyes. We focused our discussion on the textile industry because it concerns consuming goods and is considered as very polluting in terms of energy and chemicals rejected into nature. Seeing if there are new possible improvements with natural colorants in this field is of great interest. But first, in order to have a good overview of the different processes or steps of the textile industry, we will base ourselves on the following diagram (Steinberger J K et al. 2009. System boundary and processes considered for the cotton T-shirt production consumption chain): 70% of water use The dyeing process according to this diagram is the fifth step in the production process called Wet processing and is part of the finishing step of the final product (in this example a T-shirt). The textile production processes needs high volumes of water to function (Bechtold T et al. 2003) and the dyeing step of the textile uses about 70% of all water required in the entire production which makes it a high energy consuming step (Hancock M & Boxworth A, 1997) coupled with high temperatures hence not compatible with environmental protection and energy efficiency principles. The dyes used in the textile industry are mostly synthetic dyes and in order to understand them; we will have a look at the industry s evolutions and dyes characteristics. As mentioned previously, the first synthetic dyes were discovered in 1856 by the English chemist William Henry Perkin (Holme I, 2006) which led to new developments and improvements in the dyeing methods but also to reduction of costs. At that time, natural fibers such as wool, jute or silk Econoving, 18 November 2011 Page 3

were still mostly produced and used. Than, the textile market experienced an increase in demand for synthetic fibers such as polyester and nylon fibers from 1996 to 2000 whereas natural protein fibers represented a smaller market. Moreover, there was an increase in demand for cellulosic fibers which was combined with an increase in development of reactive and disperse dyes that are one of the categories of dyes. During the same period of time (1997 to 2000), the dyeing industry experienced a fierce competition and the major players were located in counties such as China, India, Korea and Indonesia which have a long experience in textile dyeing processes due to cultural background and artisanal know-how. The globalization effects and so the spread of techniques and use of synthetics and chemicals in the textile industry has also led to a marginalization of natural colorants or dyes in the dyeing process. Another aspect was a higher demand for a wider variety of colors, for more rapidity and flexibility of the production processes because of mass production which couldn t be fulfilled with natural dyes (Walk H, 2002). The synthetic dyes are numerous and listed below are the most used ones: - Sulphur dyes (mostly used for black and navy colors) - Direct dyes - Vat dyes - Indigo dyes (blue pigments) - Azotic/azo dyes - Reactive dyes (usually use high volumes of water because of the rinsing stage as well as high temperatures) - Basic dyes - Disperse dyes - Acid dyes For more detail on each of the dyeing category, read more in (Walk H, 2002). According to the Colour Index International by the Society of Dyers and Colourists (Coulor Index International: http://www.colour-index.org/), two third of organic colorants are Azo dyes and one sixth of them are metal-complexes which means that they are the most used synthetic colorants and especially for cotton dyeing. But unfortunately those colorants can reject several substances called aromatic amines that are human carcinogens according to European regulation (REACH: http://ec.europa.eu/environment/chemicals/reach/reach_intro.htm). Because of higher concern about industrial pollution, more environmental restrictions on chemicals and wastewaters were put in place which led to higher costs of eco-toxicological testing for new colorants for industrials. We can consider this aspect as an opportunity for the development and use of natural dyes at the industrial levels i.e. less environmental costs. The forecasts made in the period of 2000 about future evolutions of certain categories of dyes were stating that Azo dyes will decrease because of their toxicity and stricter regulations, that there will be a constant evolution for direct, sulfur, vat and indigo dyes and finally an increase in reactive and disperse dyes mainly because of a correlation with an increase in demand for cellulosic and polyester fibers (Walk H, 2002). Indeed, the main R&D applications were focused on dyestuffs for cellulosic and polyester fibers i.e. reactive and disperse dyes. Moreover, many developments and/or improvements in chemical reactions for the listed types of dyes were made in order to optimize their yield, lessen water use and the amount of chemicals in effluents. But those developments always favored the use of synthetic dyes from which the impacts on the environment are still important. An example of development in synthetic dyes is the increase of reactive dyes use for wool dyeing. Indeed, the dye fastness to washing for wool fiber is important and therefore needs metal complex dyes to be efficient with negative impacts on the ecosystems. Because the industry experienced an increase for low to no Econoving, 18 November 2011 Page 4

chrome in dyehouse effluents, it shifted to other types of dyes such as reactive dyes. Those dyes might be less harmful than the metal based ones used before but need more complex reactions that are more costly. To conclude the part on textile industry and synthetic dyes, we can also mention the implementation of several actions and laws from institutions and governments to ban or reduce the use of certain chemicals because of environmental and health issues. This context can push industrials towards new development and better consideration of natural dyes. This idea is also linked with eco-labeling which is actually growing fast and the new concept of eco-dyeing; dyeing using low energy consuming processes and non-toxic dyes. In this discussion we need to compare both types of dyes in order to see their respective potential for the future and compatibility with environmental preservation. Comparison of natural with synthetic dyes using an advantages and disadvantages analysis. For the comparison, we used an advantages and disadvantages approach established from information and data analyzed structured according to environmental, technological, economical, social and regulatory aspects in order to fit with eco-innovation principles. We will draw the main conclusions from this analysis for each criterion. Environmental Environment preservation is maybe the main reason why natural dyes are considered as an alternative to synthetic dyes because of their natural origins which should, in theory, be less harmful to the ecosystems and humans. It is clear that synthetic dyes are more toxic for the environment especially Azo dyes which are very polluting and mostly used because they contain vivid colors. Those types of dyes are toxic and mainly reluctant to biological treatment and also contain carcinogenic amines that can cause health problems (Corso C R & Maganha de Almeida A C, 2009). Those toxic substances are than found in wastewater and contaminate ecosystems and water sources that have negative impact on ecosystems in general. Another environmental aspect is the use of water as previously mentioned. These facts clearly show the negative impacts on environment of synthetic dyes. But natural dyes are not much cleaner. Indeed, natural dyes are classified as adjective dyes which means that they need the use of chemicals, called mordants, to help creating a chemical bond between the pigment and the fiber. Unfortunately, the use of mordants is polluting knowing that most of them contain metals such as tin, lead, copper, iron and chrome; substances that are not allowed to be rejected into water courses and rivers. Moreover, the use of such mordants is greater with natural dyes in order to produce the colors required as well as to create a good fastness to light and detergents (Hancock M & Boxworth A, 1997). Another environmental drawback of natural dyes is their production; coming mostly from plants, they need large surfaces of land in order to be cultivated and so offset space dedicated to agriculture for food production (TDV Industries Interview, 2011). Moreover, the extraction of dyes from certain plants like Madder are polluting because the process needs the use of sulphuric acid; a toxic substance. In order to reduce those drawbacks and environmental risks, some companies and research bodies in Austria promote the use of by-products from wood, food industries or agriculture in production and extraction of natural dyes with aim to reuse waste and not use land that has a different purpose (food production for example) (Bechtold T et al., 2009). Finally, research groups and industrials invest in research and development in chemical use optimization and effluent reduction for synthetic dyes which could become less harmful to the environment and still comply with technical and economical requirements. Econoving, 18 November 2011 Page 5

Technological The technological side of the dyeing process is the main strength of synthetic dyes which is the reason of their original development; they provide a wide range of colors, can be mixed together using different concentrations, have a high color fastness to light, washing and detergents which gives them a great advantage over natural dyes. In terms of proportion and concentration, for synthetic dyes only 1.5 g is used to dye 100g of fiber compared to a need of 120 to 240 g of natural dye to get the same result in terms of coloration (Hancock M & Boxworth A, 1997). Indeed, according to the answers given by a representative of the TDV Industries company, natural dyes are less resistant to washing, they have a reduced colors range compared to synthetic, less replicable colors and need a longer process compared to synthetic dyes. Some positive aspects of natural colorants for now are that they fit well with cellulosic fibers such as cotton, linen, wool and also with polyamide (TDV Industries Interview, 2011). Moreover, some improvements in mordants can provide compounds that are les harmful for the environment which will help the dye to be efficient on the fiber but such innovative mordants work only with few pigments for the moment and the process is still quite complex (TDV Industries Interview, 2011). Social In terms of social aspects concerning synthetic and natural dyes, both have advantages and disadvantages. Because of their environmental and health impacts and also because some accidents occurred in factories, synthetic dyes have a low level of social acceptability and are consumed only because there is no real alternative for the moment. For natural dyes, it is more contrasted; on one hand, they refer to a certain traditional know-how, to a link with nature and have a romantic connotation. But, on the other hand, because of the need of large surfaces to produce them, farmers and people from developing or poor countries will not accept it, knowing that food production is now a serious challenge and will become stronger in the future. Economical Considering economic dimension, synthetic dyes are at first more interesting than natural dyes. They are cheaper to produce, brighter, more color-fast and easy to apply to any fabric and to produce on high quantity to respond to industrial needs. When we compare with natural dyes, we can say that plants containing colorants will not be available as fresh material all year long which implies storage issues for the producer or the user which becomes costly. In addition, natural dyes are not originally made for dyeing synthetic fibers which account for the majority of fibers on the market and their potential use for textiles is linked closely to the type of fiber being dyed. One of the only actual possibilities for commerce is to target niche markets such as bio fibers combined with natural colorants that respond to a specific category of customers but these products have trouble finding receptivity according to the French company TDV Industries. Nevertheless, synthetic dyes are becoming more and more expensive because of higher cost for eco-toxicological tests and the fact that they are products of the petroleum industry which will experience an increase in price for oil related to scarcity. These threats will become opportunities for natural dyes in few years if the research and development keeps up and constantly improves the efficiency of natural colorants. Political and regulations Finally, when looking at political and regulatory aspects of the subject, we can state that natural dyes have an advantage over synthetic colorants. It seems that more restrictions towards chemical dyes in Econoving, 18 November 2011 Page 6

the textile and other industries are increasing which favors greener production processes and ecodyeing. Indeed, stricter laws and regulations against chemicals and synthetic substances in the national and international levels such as REACH (European Community Regulation on chemicals) are put in place to protect the environment from toxic effluents and health problems. The Global Organic Textile Standard (GOTS) which is the leading textile processing standard for organic fibers (GOTS official website, 2011) is an opportunity for companies that want to implement greener production systems in the dyeing industry and have an international recognition label that certifies their commitment to environmental protection. But by considering a different perspective, this could also slow the development and use of natural dyes in industry because of the costs involved in changing cultivation processes, machinery, extraction methods and chemical use. Moreover, there are stricter regulations on bio agriculture of the colorants-containing plants which becomes more time consuming for companies in order to get a fully integrated network that respects all environmental regulations (Couleurs de Plantes Interview, 2011). This analysis shows that each type of dyes has more assets in some aspects such as economical and technical for synthetic dyes and in political or regulatory and social for natural dyes. When looking at environmental aspects, both are considered as damaging for the ecosystems. The last part will focus more on new developments for natural dyes and possible improvements. Innovations and new developments to foster the use of natural dyes in the textile industry. As we discussed previously, the R&D is more concentrated on the optimization of synthetic dyes but the renewed interest given to natural dyes encourages more research in this field in order to see future prospects and new processes more efficient and greener. We will give three main examples about research and innovation in natural dyes to illustrate this trend. The first example is the use of enzymes and ultrasonic dyeing technique done in India which aimed at avoiding the use of metal mordants and obtaining good and/or better results than synthetic dyes. The research team used an enzyme pretreatment that was applied on cotton fabric; this technique enabled the natural dyes such as Acacia catechu and Tectona grandis to have better results and to avoid the use of metal and toxic mordants in the dyeing process which is more environment friendly. Indeed, the main advantages of this method are better absorbency, adherence and diffusion of the natural colorants into the fabric. This is economical because the cost of chemical mordants is avoided and eco-friendly. In addition, the enzymes used in the process are biodegradable and therefore do not need any specialized treatment after use. Finally, the use of ultrasound method helps to achieve a significant increase in dye exhaustion and therefore shows that this method is an effective tool in textile dyeing for more eco friendly production (Vankar P S, 2009). A second approach is to avoid the use of dyes to color cotton fabric. This study was conducted by the California Agricultural Technology Institute and consisted on the cultivation and use of naturally colored cotton to replace the use of certain dyes on cotton fabric. Some cotton plants are naturally colored and therefore do not need chemicals to dye the fiber from green to brown colors. Those types of cotton plants are more resistant to parasites and diseases than the classic white cotton but the fibers are considered weaker because of their thickness and length. Nevertheless, through nursery and improvement of quality, the naturally colored cottons can become better than the classic one but this demand modifying the cotton plant in artificial ways. Some studies mentioned in the report have found that naturally colored cotton has a higher oxygen index value than white cottons, which consists in less flammable property and using those plants could help to save up to Econoving, 18 November 2011 Page 7

50% costs which were dedicated to disposal of toxic waste. Naturally colored cotton plants are considered environmentally friendly because they are more tolerant to drought, salt and do not have to be dyed during fabric manufacturing. But one of the main concern is about the mixing of naturally colored and classic cotton plants and the risk of contamination. Indeed, producers of classic cotton need to bleach it before the dyeing process and therefore do not want to mix both types because they will have to bleach it again and will hence loose money. To conclude, some tests showed that only certain types of colored cotton plants can affect classic cotton and that it will not need more bleaching (Dickerson D K at al., California Agricultural Technology Institute, California State University, Fresno, 1999). Finally, many research groups in Austria focused their studies on the use of natural dyes on cotton, jute and synthetic fibers to test their potential. Some studies also focused more on water, chemicals, and energy consumption when using natural dyes in the whole process. Below is a synthesis on the dyeing process used by the research groups according to certain criteria that were set for the project (Bechtold T, 2003): The process used to extract the dye from the raw material that was dried out or preserved in a freezer is boiling water with application of a ratio of 1:20, corresponding to a ratio of 1 g plant material to 20 ml of water during 60 minutes. Mordants of Iron and Alum were added in the process at 90 C as we can see on the following diagram. Econoving, 18 November 2011 Page 8

The dyes were applied on cellulose fiber such as linen and wool (protein fiber) and the comparison between use of iron mordant and alum mordant shows that the first one enables a distinct shift of color depth and shade compared to the other one. Moreover, Iron mordants are used because it increases the fastness properties of the dye and the use of alum mordants in this context does not affect the light fastness as much as the other. When looking at wastewater concentration of chemicals for cellulose fibers, we distinguish a decrease of the chemical load in the wastewater when using natural colorants. Therefore, the sustainable property of natural dyes makes them an interesting class of colorants for future development in dyeing processes. The main conclusions of the test using a one-bath dyeing process show that some dyes give better results (fastness, brightness, ) than other such as the one coming from Madder. Moreover, the use of by-products from other industries such as the wood industry and agriculture will be very interesting for future development and research. According to the research teams, the future success on natural dyes will depend on their ability to meet acceptable light fastness and variety of colors, for the companies to create an efficient and organized supply network that can provide standardized quality dyes and finally, the availability of common data on toxicity and wastewater composition for the field (Bechtold T, 2003). Concluding remarks Natural dyes are for now not considered as an alternative to synthetic dyes because the most common method is to use metal chemicals in order to provide them with as much efficiency as synthetic dyes. Moreover, there is a problem of production and agriculture; to produce a sufficient volume of dyes to meet the needs of the textile industry, we will not have enough space on the earth for all the plants that will have to be cultivated and this will be contradictory with food production. Nevertheless, innovation and R&D showed new possibilities and improvements in the use of natural dyes as textile colorants but it is still on the development stage and is not yet viable on an industrial scale. As experienced through interviews with two French companies (TDV Industries and Couleurs de Plantes), we see that natural dyes are used in textile dyeing but represents only a small share of the product panel and are positioned on a niche for bio and green textile combined with bio fabrics. Therefore, natural dyes are considered as a complement to synthetic dyes instead of an alternative and a complement to bio and eco-friendly fabrics. For now, the way natural dyes are used means that they are not totally compatible with eco-innovation principles but the new processes which seek the creation of natural mordant or the use of naturally colored fabrics are on the right path to meet those principles. Econoving, 18 November 2011 Page 9

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