Sustainable dyeing technologies

Mehran University of Engineering and Technoiogy, Jamshoro, Sindh, Pakistan RMIT University, Brunswick, ViC, Austraiia 

The issues surrounding the sustainability of dyeing apparel textile materials are complex. In this chapter, dyeing is taken to include all of the preparation steps before dyeing. These two steps form the principal contributors to air and water pollution in the apparel manufacturing chain (Smith, 2003 Bide, 2007, Babu et al 2007). Each step consumes water, energy, and chemicals and results in discharges to the environment. 

Sustainable Apparel. http //dx.doi.org/10.101 /B978-l-78242-339-3.00005-4 Copyright 2015 Elsevier Lid, All rights reserved. 

The term apparel covers a wide range of consumer end uses or applications. By far the greatest volume is in the fashion apparel market. Other important apparel fabric markets include corporate and uniform wear, leisure wear, and industrial, recreational, and specialized high-performance wear. Each of these areas will have different performance requirements. Each will have its own environmental footprint. 

Fibers used in the manufacture of apparel are predominantly cotton, wool, polyester, acrylic, and rayon. The fibers are used in both woven and knitted form with the exception of acrylic fibers, which are principally used for knitwear. Fiber blends are a feature of many items of apparel wear (e.g., polyester-rayon for corporate and evening wear, polyester-cotton for shirts, and polyester-wool for suits). Technologies for dyeing the two-fiber blends are well established. However, there can be some issues with effluent. 

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The diversification of energy sources tailored to the requirements and resources of each country using nature s renewable resources such as the sun (photovoltaics), wind power, geothermal energy and biomass is a definite requirement. If solar cells are chosen to provide an alternative to fossil fuels, significant research work is needed (i) to develop new routes for the production of crystalline silicon, (ii) in the development of amorphous silicon hybrid materials that could result in enhanced efficiencies, (iii) for further development of thin-layer technology, (iv) in concerted efforts for cheaper and more stable dyes, (v) in improving the efficiency of the dye-sensitized cells and (vi) in process development to deliver enhanced device performances, ensure sustainability and reduce production costs on an industrial scale. 

This section explores the practice and technology used to apply dye to the principal apparel fibers. This leads to Section 5.6, which provides an overview of sustainability issues arising from commercial practice in the dyeing of apparel fabrics. 

A range of fixation technologies have been developed to take advantage of pad dyeing. Some have been evolutionary, whereas others have been developed specifically for a particular dye-fiber product. A summary of the key features of the various fixation technologies and their sustainability issues is given in the following sections. 

AirDye technology manages the application of color to textile without the use of water, providing a sustainable alternative to traditional cationic or vat dyeing proeesses. The process does not pollute water, greatly reduces energy use, lowers eosts, and satisfies the strictest standards of global responsibility. 

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