Bleaching chemicals

Chemical bleaching is never used on oils intended for edible use because it oxidizes unsaturated fatty acids to cause off-flavors. However, it does find wide usage for specialty linseed oil, for the paint industry, and fatty chemicals such as sorbitan esters of fatty acids and sodium stearoyl lactylate. Residual peroxide is destroyed by heating above its decomposition temperature. 

The most common chemical bleaching procedures are hypochlorite bleach for cotton hydrogen peroxide bleach for wool and cotton sodium chlorite bleach for cotton, polyamide, polyester, and polyacrylonitrile and reductive bleaching with dithionite for wool and polyamide. 

C. W. Scheele prepared and studied gaseous chlorine (Mn02 -f- HCl) but thought it was a compound 1785 Chemical bleaching (eau de Javel aqueous KOH 4-CI2) introduced by C.-L. Berthollet... 

Chemical pulp is bleached in traditional bleach plants (see Figure 21.5), where the pulp is processed through three to five stages of chemical bleaching and water washing. The desired whiteness, the brightness of the initial stock pulp, and the plant design determine the number of cycles needed. 

Chemical bleaching is used to remove colored non-washable soils and stains adhering to fibers and is accomplished by oxidative or reductive decomposition of chromophoric systems. Only oxidative bleaches are used in laundry products to a great extent. 

Agents for chemical bleaching rely on different types of peroxides. Potentiometric or amperometric biosensors that detect the highly specific and sensitive reaction of enzymes like katalases with their corresponding substrates can be used for on-line measurement [84]. The sensors can be manufactured with simple technologies at moderate cost, but their stability is not sufficient for integration in household appliances. 

Bis(l,2,3-triazol-2-yl)stilbene brighteners have high efficiencies and good lightfastness and are very resistant to chemical bleaches. They are employed as brighteners for cotton and polyamides. An example is 4,4 -bis(4-phenyl-l,2,3-triazol-2-yl)stilbcnc-2,2 -disulfonic acid dipotassium salt (32) [52237-03-3] [59],... 

A reactive dye inclusion compound 1 (Figure 12) was prepared by condensing disodium salt of 7-[4-(methylamino)phenylazo]-2,4-naphthalenedisulfonic acid with cyanuric chloride and sodium 3-aminobenzenesulfonate (1 1 1) in the presence of hexaMs(2,3,6-tri-0-methyl)-a-cyclodextrin [41], Solutions of the bright yellow rotaxane 1 are more resistant to chemical bleaching than the uncomplexed dye. This compound anchored to mercerized cotton 2 also showed more photofading resistance [42],... 

Both for the environment and for yourself, it s best to use recycled paper as much as possible. Toilet paper from the natural products store is an acceptable substitute for the more luxurious non-recycled toilet paper which is chemically bleached and often colored and perfumed. 

In the last 20 years the pyrazole ring has attracted much attention, as it has become fairly accessible and shows diverse properties. Besides the traditional interest in pyrazole derivatives which have been the basis of numerous dyes and drugs, a number of pyrazole anesthetics have appeared.12 Recently it was established that pyrazolines are not only of interest as intermediates in the synthesis of cyclopropanes, but also as effective chemical bleaching agents, and as luminescent and fluorescent substances.3-8 The ease with which... 

Did you know that many of the chemical products in your home are hazardous, too For example, common household bleach, when used as directed, is safe for disinfecting and whitening clothing. Hazard labels on bleaching products, however, warn against mixing bleach with acids, household ammonia, or products that contain these chemicals. Bleach, when combined with acids, produces toxic chlorine gas. The products of combining bleach with ammonia are explosive. 

They are prepared by sulfonation of an alkyl aryl compound under vigorous conditions. This reaction leads to coloured products. Peroxygens are used to chemically bleach these compounds to give lightly coloured materials.87-91 To... 

The oils, fats and waxes are extracted from vegetable and animal sources. To produce acceptable, soluble and usable products with respect to colour, odour and impurities, they require chemical purification. The coloured and odorous materials result from polyunsaturates and aerial oxidation products. Hydrogen peroxide has been used successfully for many years. Tables 6.7 and 6.8 summarizes the current methods used to chemically bleach oils, fats and waxes. 

Trevor Levere and I have shown recently,2 Watt deployed theoretical ideas about airs in that project. Moreover, those ideas had continued to evolve and seem to have been crucially supplemented by notions about solutions garnered from the French chemist Berthollet during Watt s involvement with chemical bleaching in the late 1780s. 

White wax is the chemically bleached form of natural beeswax see Section 13. 

White wax is a chemically bleached form of yellow wax and is used in similar applications for example, to increase the consistency of creams and ointments, and to stabilize water-in-oil emulsions. White wax is used to polish sugar-coated tablets and to adjust the melting point of suppositories. 

Ecozyme [Swan], TM for a xylanase-based enzyme that reduces chemical bleaching agents up to 25% with enhanced pulp quality. 

Chemic bleach Available Cl 0.6 g/1, cold pad-batch over-night... 

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