Peroxide bleaching of cotton

Anionic softener for fabric finishing can be combined with all types of filling agents softener with stabilizing effects in peroxide bleaching of cotton yarns. 

Sanperox . [Sandoz] Stabilizer with sequestering and dispersing properties for peroxide bleaching of cotton and blends. 

Maekawa, M., Hashimoto, A., and Tahara, M. (2007). Effects of pH in hydrogen peroxide bleaching of cotton fabrics pretreated with ferrous sulphate.. Text Res. L 77(4), 222-226. 

Uses Wetting agent, auxiliary, detergent, stabilizer for the hydrogen peroxide bleaching of cotton and its blends... 

Uses Activator, stabiiizer, surfactant, bieaching agent for discontinuous peroxide bleach of cotton... 

Uses Bleaching assistant, wetting agent for continuous peroxide bleaching of cotton... 

The consumption of hydrogen peroxide in the manufacture of high quality paper is expected to increase strongly, at least in the USA. In the textile industry, hydrogen peroxide is mainly used for the bleaching of cotton, although it is also used for the bleaching of wool. 

Though the use of peracetic acid has been suggested for bleaching of cotton but has never reached the commercial success like hypochlorite, chlorite and peroxide [89]. The mechanism of reaction is somewhat similar to that of hydrogen peroxide. 

When bleaching is requited, a reductive bleach with sodium hydrosulfite and sodium metabisulfite is used. Cotton blends may requite a hydrogen peroxide bleach at pH 9.0—9.5 prior to or iastead of the normal reductive bleach. Chlorine-type bleaches which damage elastomeric fibers are avoided. 

The advantages favouring the pre-eminence of hydrogen peroxide (over 90% of cotton goods are bleached with peroxide) include [143,225] ... 

Thus the detailed mechanism of peroxide bleaching is not yet finally resolved. It should be borne in mind, however, that the work of Dannacher and Schlenker was carried out at 60 °C on tea-stained cotton, whereas Spiro and Griffith studied the decolorisation of individual colorants at 21-25 °C in the absence of a textile substrate. 

The possible benefits of prescouring to remove such contaminants should also be considered. Alkaline pretreatments, including boiling off of cotton, have a profound effect on AOX values after chlorite bleaching (Tables 10.21 and 10.22). It can be beneficial, from the viewpoint of both AOX and whiteness, to follow a chlorite bleach with a peroxide treatment. Linen yarns after an alkaline scour and chlorite bleach gave a whiteness value of 63.9 with an unacceptably high AOX value of 8.0 ppm. These results were improved to 78.5 and 1.2 ppm respectively after peroxide treatment [224]-... 

FBA may be applied by exhaustion from the same bath. If the polyester portion of the blend is to be bleached with sodium chlorite, the cotton is usually brightened in a second step since most FBAs for cotton are destroyed by sodium chlorite. Both types of FBA are normally compatible with a hydrogen peroxide bleaching process. 

Fischer et al. (21) demonstrated that the endotoxin content of raw cotton is significant (300 ng/gm lint) and is markedly decreased by washing and/or bleaching of the cotton, and by heating the cotton in hydrogen peroxide. Only prolonged high heat results in a complete loss (5 log decrease) of endotoxin activity from cotton dust. 

The application of chlorine bleach on the basis of hypochlorite/chlorite for the preparation of cotton/linen results in considerable formation of AOX in the effluents. Such processes should be replaced by bleach processes on the basis of peroxide. To obtain a sufficient degree of whiteness during the bleach, a two-step bleach (peracetic acid/peroxide) process has been proposed in the literature [25-27]. Such processes avoid the formation of chlorinated organic compounds (AOX). 

The hydrogen peroxide formed in situ can be used for bleaching22 of the textile fabric (wool, cotton), and its concentration is an important parameter concerning the quality of the bleached product. Cotton is mostly... 

PLEX HT is a blend of chelating agents which has the ability to dissolve iron rust from cotton and cotton blend fabrics in strong caustic solutions such as are used in saturation of cotton fabric prior to continuous peroxide bleaching. It also has the ability to keep the chelated iron from redeposition as the pH drops during subsequent rinsing. 

SEQ 100 is used in preparation of cotton and cotton blend fabrics and also can be used in scouring synthetic fabrics when there is a substantial amount of interfering heavy metals on the fabrics. A concentration of 0.1% on the weight of the bath in the caustic scour prior to peroxide bleaching will remove calcium, magnesium and copper but very little iron as the metal or as the rust. If it is necessary to remove ron or rust, other products such as SEQ CF in strong caustic are recommended. 

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