**3. Ultraviolet technology**

Light is electromagnetic radiation or radiant energy traveling in the form of waves [29]. The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radia‐ tion. The "electromagnetic spectrum" of an object is the characteristic distribution of electro‐ magnetic radiation emitted or absorbed by that particular object. The electromagnetic spectrum extends from low frequencies used for modern radio communication to gamma radiation at the short-wavelength (high-frequency) end, thereby covering wavelengths from thousands of kilometers down to a fraction of the size of an atom [30]. UV energy is found in the electromagnetic spectrum between visible light and x-rays [29].

**Figure 3.** A diagram of the electromagnetic spectrum [30]

with hollyhock gives fair to good fastness properties in sonicator in 1 hour and shows good

*Battu et al. (2010)* observed that in wool dyeing at 85°C with acid dyes, ultrasound caused an improvement of the dye uptake as much as 25%, or dyeing time would be nearly 20% short‐

*Yukseloğlu and Bolat (2010)* stated that the wool fabrics have presented similar color yield (K/S) and acceptable color differences (ΔE) with the use of ultrasonic energy. Ultrasonic en‐ ergy was found to be advantageous to be used for wool dyeing at lower temperatures (such as 80°C and 90°C) and lower dyeing times (i.e. 80 min. or 90 min.) as an alternative process

*McNeil and McCall (2011)* investigated the effects of ultrasound at 35-39 kHz on several wool dyeing and finishing processes. Ultrasound pre-treatment increased the effectiveness of sub‐ sequent oxidative-reductive bleaching, but had no effect on the uptake of acid leveling and acid milling dyes. The pre-treatment retarded the uptake of reactive dye, possibly by in‐ creasing the crystallinity of the fiber or removing surface bound lipids. Ultrasound did not improve dyeing under conditions that are currently used in industry, but did show potential to reduce the chemical and energy requirements of dyeing wool with reactive and acid mill‐

*Atav and Yurdakul (2011)* investigated the effect of ultrasound usage on the color yield in dyeing of mohair fibers. They found that dyeing in the presence of ultrasound energy in‐ creases the dye-uptake of mohair fibers and hence higher color yield values are obtained. The difference between the samples dyed in the presence and absence of ultrasound, was greater for darker shades and for dyeing carried out in acidic medium (pH 5), and also for shorter dyeing periods. Furthermore there is no important difference between washing fast‐ ness and alkali solubility values of fibers dyed in the presence and absence of ultrasound

*Ferrero and Periolatto (2012)* studied the possibility of reducing the temperature of conven‐ tional wool dyeing with an acid leveling dye using ultrasound in order to reach dye uptake values comparable to those obtained with the standard procedure at 98°C. Dyeings of wool fabrics were carried out in the temperature range between 60°C and 80°C using either me‐ chanical or ultrasound agitation of the bath and coupling the two methods to compare the results. For each dyeing, the dye uptake curves of the dye bath were determined and the better results of dyeing kinetics were obtained with ultrasound coupled with mechanical stirring. Finally, fastness tests to rubbing and domestic laundering yielded good values for

Light is electromagnetic radiation or radiant energy traveling in the form of waves [29]. The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radia‐

samples dyed in ultrasound assisted process even at the lower temperature [22].

dye uptake as compared with conventional dyeing [24].

for conventional dyeing (100°C and 144 min) [26].

ing dyes, but not acid leveling dyes [27].

**3. Ultraviolet technology**

[28].

er than conventional dyeing [25].

108 Eco-Friendly Textile Dyeing and Finishing

Ultraviolet or UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye [31]. Ultraviolet radiation constitutes to 5% of the total incident sunlight on earth surface (visible light 50% and IR radiation 45%). Even though, its proportion is quite less, it has the highest quantum energy compared to other radiations [32]. Scientists classify UV ra‐ diation into three types or bands: UVA, UVB, and UVC (Fig. 4). The ozone layer absorbs some, but not all, of these types of UV radiation [33].


The deleterious effects of solar irradiation are perceived as changes in texture and color, dry‐ ness, etc., and can be evaluated in terms of reduced elasticity, increased porosity or swelling properties, altered

*Millington (1998)* found that UV radiation of wool fabric exhibits some physical and chemi‐ cal changes on its surface. This interaction not only modifies the fabric of wool but also im‐ prove the shades particularly grey and black. It also helps in even dyeing, deeper shades,

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

111

*Xin et.al (2002)* exposed wool samples to UV radiation for 60 min. and investigated the sur‐ face modification of the wool fiber by X-ray photoelectron spectroscopy. The chemical change caused by the UV treatment was identified as surface oxidation of cystine (disul‐ phide bonds) and thereby induced changes in the dyeing properties of the wool. The dyea‐ bility of UV-treated and untreated wool samples was determined at temperatures of 45, 50, 55 and 60°C using C.I. Acid Blue 7. The UV-treated wool samples showed greater levels of dye uptake compared with those of the untreated samples. The adsorption behavior and dif‐ fusion coefficients were also studied. The dyeing properties of wool were enhanced by UV radiation due to the increased diffusion coefficient of the dyes in the treated wool fibers [42].

Ozone is a natural occurring gas that can be both beneficial and detrimental to organisms on Earth. It is important that sufficient amount of this pale blue gas is present in the strato‐ sphere, where O3 molecules would shield most of the UV radiation from reaching Earth [43]. Although ozone is a blue colored gas at normal temperatures and pressures; because of its low concentrations in its applications the observation of this blue color of ozone is impossi‐ ble [44]. Ozone gas has a pungent odor readily detectable at concentrations as low as 0.02 to

Ozone was first generated and characterized by a German scientist named Schonbein in 1840 [46]. Ozone is a nonlinear triatomic molecule possessing two interoxygen bonds of

Ozone is formed naturally in the atmosphere by photochemical reaction with solar UV radi‐ ation and by lightening. It can also be generated artificially. Three most common ways of

0.05 ppm (by volume), which is below concentrations of health concern [45].

equal length (1.278 A) and an average bond angle of 116°49' [47].

chlorine free printing and improve the photo bleaching of wool [41].

**4. Ozone technology**

**Figure 5.** Ozone molecule [48, 49]

generating ozone artificially are:

**Figure 4.** Classification of ultraviolet radiation [35]

dye sorption characteristics, and photofading of natural or artificial hair color [36]. The chemical changes caused by short-term UV irradiation of wool are confined to fibers at the fabric surface and UV is unable to penetrate beyond the surface to weaken the bulk fibers responsible for the mechanical strength. This has enabled the potential application of UV technology as a surface-specific treatment in several areas of wool processing [37]. For wool the UV-absorbing species are aromatic amino acid and cystine residues in the protein struc‐ ture which absorb strongly below 350 nm. UVC radiation (200-280 nm) is the most effective range for modifying wool fiber surfaces [38].

The most commercially used process for antifelting and antipilling of wool is based on chlorination. However, recent concern over the release into the environment of adsorbable organohalogens (AOX) in process effluents has prompted the development of alternative, AOX-free processes. Different types of radiation techniques, such as ultraviolet radiation, are utilized as alternatives to chlorination in wool processing [39]. UV treatment can add value in coloration (dyeing and printing), since it is predominantly surface fibers in a fabric that absorb, reflect and scatter light. Photomodification of the surface fibers can allow:


Modification of the dye uptake by exposure of wool fabric to UV radiation before dyeing has been known since the early 1960s. For most dye classes, UV-irradiated fabric takes up significantly more dye than untreated and when fabrics are irradiated through stencils, intri‐ cate tone-ontone effects can be produced [37]. Some literature related to the use of ultravio‐ let technology in dyeing of proteinous fibers is summarized below.

*Millington (1998)* stated that UV irradiation of wool can significantly increase dyeing color yields. The use of 1:1 metal-complex dyes was found to be particularly effective, and a 3% o.w.f. dyeing on UV-treated fabric could produce a better depth of shade than a 5% dyeing on untreated fabric [40].

*Millington (1998)* found that UV radiation of wool fabric exhibits some physical and chemi‐ cal changes on its surface. This interaction not only modifies the fabric of wool but also im‐ prove the shades particularly grey and black. It also helps in even dyeing, deeper shades, chlorine free printing and improve the photo bleaching of wool [41].

*Xin et.al (2002)* exposed wool samples to UV radiation for 60 min. and investigated the sur‐ face modification of the wool fiber by X-ray photoelectron spectroscopy. The chemical change caused by the UV treatment was identified as surface oxidation of cystine (disul‐ phide bonds) and thereby induced changes in the dyeing properties of the wool. The dyea‐ bility of UV-treated and untreated wool samples was determined at temperatures of 45, 50, 55 and 60°C using C.I. Acid Blue 7. The UV-treated wool samples showed greater levels of dye uptake compared with those of the untreated samples. The adsorption behavior and dif‐ fusion coefficients were also studied. The dyeing properties of wool were enhanced by UV radiation due to the increased diffusion coefficient of the dyes in the treated wool fibers [42].
