Green Chemistry in Textile
Mrs YogitaAgrawal ,Ms Reena Kumrawat, Mr Shyam Barhanpurkar, Mr Tanveer malik
(Author: Asst Prof SVITS,Indore)
Green chemistry is the chemistry that-Doesn’t hurt nature, Reduce or eliminate the use or generation of hazardous substances, Provides more eco friendly alternative, Prevents formation of waste, Creates new knowledge based on sustainability i.e. sustainable chemistry, Takes a life cycle approach to reduce the potential risks throughout the production process.
Recently steps have been taken to make textile materials and processing more environmentally friendly (or ‘greener’), including FIBER production, dyes and auxiliaries, solvents, optimized and efficient processing with recycling of water and chemicals, bio-processing, the elimination of hazardous chemicals and the recycling of textile materials.
The purpose of this article is to review the information on the sectors such as textiles, which have extensive use of both chemicals and water, green chemistry measures can not only play a role in improving their resource efficiency but also help reduce the effluent generated thereby reducing the adverse environmental impact of the industry. Many multinational companies have already embarked on the process of conducting extensive research to alter/enhance their production processes in order to reduce their environmental footprint, manufacturing cost and increase safety of their end products leading to sustainable development.
Keywords: green chemistry; sustainability; textile fibers; textile dyeing and finishing; ionic liquids
There is growing confidence among industry by improving the overall resource efficiency, green chemistry can provide financial benefits to chemical companies from lower material usage, energy and capital expenditure costs in addition to environmental benefits. Moreover, the export oriented industries like Textile, Pharmaceutical and Pesticides are under pressure to find greener alternatives to comply with regulations in major export markets like Europe and United States. Indian industry has started taking small steps towards incorporating these principles while developing green chemistry solutions and approaches. Though, the sector is still in its infancy, it can definitely aid the industry to achieve environmental as well as resource sustainability.
Chemical sector is among the key focus sectors of the Make in India initiative. In sectors such as textiles, which have extensive use of both chemicals and water, green chemistry measures can not only play a role in improving their resource efficiency but also help reduce the effluent generated (both quantum and type) thereby reducing the adverse environmental impact of the industry. Many multinational companies have already embarked on the process of conducting extensive research to alter/enhance their production processes in order to reduce their environmental footprint, manufacturing cost and increase safety of their end products.
Drivers for green chemistry practices in Indian Industries
- Buyer Demand and Regulation driving export oriented industries: This is relevant to the industries like textile apparel, pharmaceutical and pesticides which are heavily export oriented and will lose business if they don’t comply to
- Increasing production cost:Due to increasing resource scarcity the resource cost is increasing. This is in turn increasing the overall production cost which directly affects the top line and the bottom line of any company. Therefore cost reduction is catalyzing action in resource intensive sectors.
- Market Competitiveness and need for innovation:Customers are continually demanding better product at a reasonable cost. To remain competitive, companies have to innovate continuously and figure out new ways to provide better products at minimum cost. This is increasing the uptake of green and progressive chemistry in sectors like pesticides and pharmaceutical.
Right now the market for the green chemistry is quite niche in the Indian market at the moment, but is expected to grow into a full fledge industry accounting for almost US$10 billion by 2020. Buyer demand and regulations in the export market as well as the ever reforming regulations in India are going to drive the adoption of green chemistry in Indian Industry.
The Greening of the Cotton Supply Chain
There are new processing technologies that are significantly improving the sustainability of the entire supply chain for cotton products. While cotton cultivation practices have improved vastly in recent years, including the development of varieties that have increased yields and require far less chemical and water input, new dyeing and finishing technologies also require fewer chemicals and consume less energy and water while also releasing cleaner effluent. Process technologies highlighted include new enzymes and one technologies that replace harsh chemicals in fabric finishing, very low-moisture foam dyeing technologies, waste- and solvent-eliminating digital printing technologies, low-salt reactive dyes, bleaching processes that drastically reduce water and energy use, and technologies that combine dyeing and finishing in one step, among other technologies. The video also presents the point of view of respected retailers who expect
manufacturers to implement these new green technologies as a prerequisite to a continuing business relationship.
What Is Green :
Green connotes the general idea that a product or a process is beneficial to, or at least has minimal impact on, the environment with regard to energy, resource and raw material usage; greenhouse gas and toxic emissions; and/or waste generation. It often is interchangeable with environmentally friendly, eco-friendly and other general terms. Sustainable is a broader term that encompasses not only the environment, but also economic and social equity considerations. A sustainable product has minimal impact on the environment in that harvesting or resource usage does not deplete or permanently damage the resource; plus, it can be produced in an economically viable way and it is produced with consideration for the welfare of employees and others impacted by the production. Cradle-to-cradle refers to a regenerative life cycle in which no material making up a product becomes waste because non compatible materials in the product can be separated and all can be recycled and reused for the same purpose as the original virgin material. This is in contrast to a cradle-to-grave product that cannot be recycled and ends up in a landfill at the end of its useful life, or a cradle-to-gate product whose environmental footprint has been calculated from raw material acquisition through the manufacturing process.
Principles of green chemistry:
The following objectives for green chemistry:
(1) Waste management: elimination or minimization of waste.
(2) Atom economy: no or lower wastage of atoms.
(3) Catalysis: catalysts are preferred to stoichiometric reagents (the latter are used in excess and work only once, whereas catalysts are mostly recovered, recycled and reused).
(4) Direct reactions: use of minimum or fewer reaction steps; derivatives or intermediate steps use additional reagents and have the potential to generate more waste.
(5) Safer reactions: synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
(6) Renewable raw materials: use of renewable and non-depleting feedstock’s.
(7) Safer products: preservation of the efficacy of functioning while reducing toxicity.
(8) Biodegradability: use of easily and harmlessly degradable chemicals with no accumulation in the environment.
(9) Green auxiliaries: use of auxiliary substances (e.g. solvents, separation agents) should be avoided wherever possible and where absolutely necessary, should preferably be innocuous.
(10) Energy economy: saving of energy should be achieved preferably by using reactions that take place under ambient temperature and pressure conditions.
(11) Safer by-products: real-time monitoring and control and reuse of by-products.
(12) Hazard control: avoidance of hazardous chemicals to minimize the chance of explosions, fire and harmful releases.
Development of green solvents
In classical chemical processes, solvents are used extensively for dissolving reactants, extracting and washing products, separating mixtures, cleaning the reaction apparatus and dispersing products for practical applications. While the invention of various exotic organic solvents has resulted in some remarkable advances in chemistry, many of the conventional non-aqueous solvents represent a great challenge to green chemistry because of their toxicity and flammability.
- Conventional solvents
Most organic solvents are volatile and unless controlled will escape into the workplace and the atmosphere, where they can be instrumental in causing photochemical smog. Many hydrocarbon and oxygenated solvents readily evaporate and are highly flammable; hence, their use needs to be managed carefully to minimize the risks of fire or explosion, particularly during loading and unloading for storage or transport, during storage itself and when being used in bulk. Safe-handling information provided by the supplier should be carefully followed.
Solvents produced from renewable resources such as ethanol produced by fermentation of sugar-containing feed stock; starchy materials or lignocelluloses materials may be selected. This substitution for petrochemical solvents leads to an avoidance of the use of fossil resources (petrochemicals) and fossil-fuel-related emissions of CO2 into the environment.
- Supercritical fluids
The most promising supercritical liquid, scCO2, is being intensively studied as a potential solvent for various purposes because, it avoids the use of CFCs, and thus reduces ozone depletion
- Ionic liquids
Molten salts have unusual solvating powers for polar materials, and the low melting point organic salts have been found to be an attractive alternative to aprotic polar solvents like dimethyl formamide, dimethyl sulphoxide.
- Non-volatile solvents
Liquid fractions of polyethers [such as poly (ethylene glycol)] and siloxane polymers are particularly inexpensive non-volatile green solvents. They are non-flammable, generally non-toxic to humans and aquatic life, biodegradable (less so for the siloxanes), and available in a wide range of polarities.
- Ester solvents
Both volatile and non-volatile ester solvents are used as carrier oils, plasticizers and coalescent, for example, isopropyl laurate, rapeseed methyl ester (used as biodiesel), glycerol triacetate and dibasic ester (DBE) has accepted as phthalate-free plasticizers and as biodegradable carrier oils for eco-friendly inks.
The characteristics of green chemicals are as follows:
- Prepared from renewable or readily-available resources by environmentally-friendly processes;
- Low tendency to undergo sudden, violent, unpredictable reactions such as explosions;
- Non-flammable or poorly flammable;
- Low toxicity and absence of toxic constituents, particularly heavy metals;
- Low tendency to undergo bio-accumulation in food chains in the environment.
One of the best approaches to a greener environment is to save energy by consuming fewer resources. Processes like heating, cooling, stirring, distillation, compression; pumping and separation require electrical energy which is often obtained by burning fossil fuel. This results in the release of carbon dioxide into the atmosphere, thereby contributing to global warming. Green power is a subset of renewable energy and it represents those renewable energy resources and technologies that provide the highest environmental benefit. Green power sources produce electricity with an environmental profile superior to conventional power technologies and produce no anthropogenic (human-caused) greenhouse gas (GHG) emissions. The EPA defines green power as electricity produced from solar, wind, geothermal, biogas, biomass and low-impact small hydroelectric sources. Customers often buy green power to avoid environmental impacts and for its greenhouse-gas-reduction benefits.
The use of fertilizers and pesticides/herbicides/defoliants is the main contributor to both energy consumption and eco toxicity, but there was conflicting evidence about the contribution of other stages in production with EDIPTEX, reaching the conclusion that eco toxicity from the production phase for traditional cotton is less significant. A shift to organic cotton could significantly reduce eco toxicity, but organic cotton has greater impact on agricultural land occupation due to its lower yield. (It is worth noting that, in any case, around 66% of the cotton now grown is genetically modified to decrease the need for pesticide/herbicides/defoliants.)
Synthetic fiber production
Nylon and acrylic FIBERs are the most energy intensive synthetic fibers to produce and are technically the most difficult to recycle.
Regenerated cellulose fiber production
It is found that viscose is the most energy intensive regenerated cellulose fiber to produce, whether or not various types of wood or bamboo (the predominant sources of raw material in regenerated cellulose fiber manufacture) are used.
Agents used in FIBER processing
In terms of its contribution to adverse environmental impact, palm oil was identified as especially significant in its use as a feedstock for the manufacturing of soaping agents and softeners; the scouring stage was highlighted as an issue in relation to wool, and dye carriers were highlighted as an issue in relation to polyester.
The impact from transport is relatively low except for those arising from photochemical oxidant formation (smog) which comes from the use of trucks, ships and planes. It is estimated that 8% of textiles imported are carried by air freight and the rest (92%) are by ship. Although air freight only accounts for a small share of distribution, its impacts are proportionally much higher.
Energy requirements and eco toxicity associated with the use phase of textile products primarily relate to laundering and drying processes, particularly washing energy and use of detergents, and can be influenced by FIBER choice and blends.
The findings also highlighted the potential benefits of more sustainable systems of resource use associated with the disposal phase, with the benefits from reuse, recycling and energy recovery being specifically highlighted
Sustainable production and consumption can only be achieved if all market contributors take responsibility. Industrialists, retailers and consumers should take ecological factors into account in every decision-making process. Manufacturers have been changing their attitudes; there has been an increasing awareness that many products could be produced under better conditions with greater respect for the environment, for example, by using less energy, attaining better yields, creating less pollution of water or air, generation of less waste and fewer (or no) unwanted by-products. Wet-processing part of the textile industry continues, it is clear that there continues to be scope for it to continue to ‘green’ its processes and the chemistry involved. In almost every case of pollution, the fundamental problem for the textile industry is found to be low process inefficiency and a poor understanding of the life cycle of textile chemicals. It is important that chemists and engineers work together to develop new sustainable processes as only by combining the best ideas from both areas will the required technological leaps be made. Improvements have occurred since the industry began to use new test regimes to benchmark the environmental performance of textile chemicals, but it appears that the dialogue between the textile industry, the technical-consulting community. The application of the principles of green chemistry and other aspects of clean technology will increasingly lead to more environmentally-compatible manufacturing systems with probable future priorities focusing on ‘Just-in-Time’ manufacturing, small and intensive plants based on use of local resources (replacing the traditional giant-sized chemical plants), plant-based feedstock’s, clay-based reagents and catalysts, and it is quite possible, as transport increasingly becomes an issue, that manufacturing will become more focused
on regional needs rather than global market opportunities.
A systematic eco-plan can lead business to such an extent that it should:
- Help customers and employees to live a healthier lifestyle;
- Set new standards in ethical trading;
- Send zero waste to landfill;
- Develop sustainable sourcing routes;
- Become carbon neutral or have a ‘net zero carbon footprint’ by balancing measured
amount of carbon released with an equivalent amount sequestered or by offset.
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