Bleaching process

Of these materials zein, the maize protein, has been used for plastics on a small scale. It can be cross-linked by formaldehyde but curing times are very long. Complicated bleaching processes have led to the production of almost colourless samples in the laboratory but the process cannot readily be extended to large-scale operation. The cured product has a greater water resistance than casein. Proteins from soya bean, castor bean and blood have also been converted into plastic masses but each have the attendant dark colour. 

Bleich-mittel, n. bleaching agent, decolorant, -151, n. bleaching oil. -prozess, m. bleaching process, -pulver, n. bleaching powder. Bleichromat, n. lead chromate. 

Titanium is being employed in the bleaching industry where the good corrosion resistance of the material makes it particularly suitable for equipment in both textile and paper pulp bleaching processes. In the dye-stuffs industry, the inertness of titanium eliminates any products of corrosion which might cause discoloration of the products. A similar situation can also exist in areas like the plastics, pharmaceuticals, and food-stuffs industries. 

The bleaching process, in contrast, poses major difficulties. Traditional paper bleaching uses chlorine gas, which is reduced to chloride anions, cr, as it oxidizes the colored pigments in wood pulp. The chloride anion is not a pollutant, as it is a major species in the oceans. Unfortunately, chlorine processing also generates small quantities of chlorine-containing dioxins such as 2,3,7,8-tetrachloro-dibenzo-p-dioxin, whose stmcture (below) appears less formidable than its name ... 

New Chemistry, Including Pulp Bleaching Processes, of the Golden-Aged, Water-Soluble Compound, Tris(hydroxymethyl)phosphine... 

This method of making soda ash is called the Solvay process. Discovered in 1861 by Belgian businessman Ernest Solvay (1838-1922), the Solvay process was used in the commercial production of soda ash in the 1870s, and it is still in use today. Soda ash is used in the manufacture of glass and soap. It is also used in the bleaching process for paper and cloth. 

Common Chemicals Used in Elemental Chlorine Free (ECF) and Total Chlorine Free (TCF) Bleaching Processes... 

Chlorinated phenolic compounds. Chlorinated phenolic compounds include phenols, guaiacols, catechols, and vanillins substituted with from one to five chlorine atoms per molecule. Typically, bleaching processes that result in the formation of 2,3,7,8-TCDD and... 

NCASI Technical Workshop, Effects of Alternative Pulping and Bleaching Processes on Production and Biotreatability of Chlorinated Organics, NCASI Special Report 94-01, February 1994. 

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