Bleaching yellow

Pulp and paper industries Monitoring of bleaching, yellowing Schmidt, 2000 ... 

White beeswax, white wax, bleached yellow wax, bleached ktswtx. Prepd by Oxidizing yellow beeswax cakes with peroxide Or in sunlight. Yellowish-white. Properties similar to those of yellow beeswax, except for a slightly different taste Preferred to yellow beeswax in cosmetics... 

Definition Purified wax from the honeycomb of the bee. Apis meiiifera-, commonly called white wax when bleached, yellow wax when not bleached... 

CAS 8006-40-4 (white) 8012-89-3 (yellow) EINECS/ELINCS 232-383-7 FEMA2126 (wh.) INS901 E901 Synonyms Cera alba White beeswax White wax Yellow beeswax Yellow wax Definition Purified wax from the honeycomb of the bee. Apis mellifera] commonly called white wax when bleached, yellow wax v en not bleached Properties Brown or wh. (bleached) solid with faint odor si. balsamic taste pract. insol. in water si. sol. in cold alcohol sol. in hot alcohol, chloroform, benzene, ether, C, and oils dens. 0.95 m.p. 62-65 C acid no. 17-24 sapon. no. 84 Toxicology Essentially nontoxic mild allergen may cause contact dermatitis, human... 

Carnauba Wax kar- n6-bo, k -no- u-bo (1854) n. Extremely hard wax obtained from the leaves of a Brazilian tree. It appears on the market in several grades, such as bleached, yellow, fatty gray, and chalky gray. The wax has the following approximate constants mp, 84°C, Sp gr, 0.998 acid value, 2 saponification value, 80 iodine value, 13. It is a constituent of wax polishes, and has some application in matt, overprinting, and baking varnishes. Its solubility is of a very low order in most varnish solvents and other constituents. Syn Brazil wax. 

The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

Liquid chlorine dioxide, ClOj, boils at 284 K to give an orange-yellow gas. A very reactive compound, it decomposes readily and violently into its constituents. It is a powerful oxidising agent which has recently found favour as a commercial oxidising agent and as a bleach for wood pulp and flour. In addition, it is used in water sterilisation where, unlike chlorine, it does not produce an unpleasant taste. It is produced when potassium chlorate(V) is treated with concentrated sulphuric acid, the reaction being essentially a disproportionation of chloric(V) acid ... 

Flour Bleaching Agents and Bread Improvers. Freshly milled flour contains carotenoid pigments that cause the flour to have a yellow color. In addition, when the flour is made into dough the product is sticky and unmanageable. As the flour ages, a natural process takes place which turns the flour white and improves its baking qualities. Because the natural process takes quite a bit of time, additives are used to speed up the process. 

Pa.le Crepes. Sri Lanka is the largest producer of crepe mbber, as either thin pale crepe or thick pale crepe, which accounts for 35% of mbber production. Pale crepes are divided into one of three classes, depending on the manufacturing process (11,12) fractionated and bleached mbber (FB) unfractionated, but bleached mbber (UFB) or yellow fraction mbber (YF). 

Another test method appHcable to textiles is ASTM E313, Indexes of Whiteness and Yellowness of Near-White, Opaque Materials. The method is based on obtaining G, ie, green reflectance, and B, ie, blue reflectance, from X, Y, and Z tristimulus values. Whiteness and yellowness index are then calculated from the G and B values. This method has particular appHcability to measurement of whiteness of bleached textiles. AATCC test method 110 also addresses measurement of the whiteness of textiles. 

In hair coloring a light ash blond shade may require as Httie as 0.5—1% of intermediates, whereas a tme black may require up to about 5%. In principle, the formulator blends precursors that yield red, blue, and yellow dyes. The base in which the components are dissolved or suspended is similar to that used in simple bleaches and may include alkanolamides, various types of surfactants, thickening agents, and solvents. Removal of undesirable dyes is achieved by treating the discolored hair with a powerful reductant of the sulfite family. 

The resultant yellow sodium cellulose xanthate is dispersed in an aqueous caustic soda solution, where some hydrolysis occurs. This process is referred to as ripening and the solution as viscose . When the hydrolysis has proceeded sufficiently the solution it transferred to a hopper from which it emerges through a small slit on to a roller immersed in a tank of 10-15% sulphuric acid and 10-20% sodium sulphate at 35-40°C. The viscose is coagulated and by completion of the hydrolysis the cellulose is regenerated. The foil is subsequently washed, bleached, plasticised with ethylene glycol or glycerol and then dried. 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Green-yellow Odor Like bleach solution. 

Sodium hypochlorite is usually sold in solution in water, where it makes a greenish-yellow liquid. (It is too hygroscopic—it absorbs water from the air—to be used conveniently in solid form.) Household bleaches usually contain sodium hypochlorite in a 3 percent to 6 percent solution. Some sodium hydroxide (lye) is added to keep the pH high to avoid decomposition. If the solution is made more acidic, sodium hypochlorite will dissociate, producing chlorine gas and oxygen. 

Chlorine dioxide has an odd number of electrons and is a paramagnetic yellow gas. Despite the environmental damage it creates, it is often used to bleach paper pulp, because it can oxidize the various pigments in the pulp without degrading the wood fibers. 

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