Chlorine bleaching process

Compounds Formed during Chlorine Bleaching Process... 

Today, the pulp and paper industry operates with two main pulping processes and three bleaching processes. The latter are the chlorine bleaching process, the elementary chlorine-free (ECF) process, and the totally chlorine-free (TCF) process they are compared in Table 6.4. 

Dioxins and furans in biota near 46 puop and paper mills using the chlorine bleaching process. Chemosphere 27(l-3) 279-86. 

The use of hydrogen peroxide in pulp bleaching is now in widespread use as the industry strives to eliminate chlorine from the bleaching process. This has arisen over environmental concerns about organochlorine compounds being discharged into the environment, which are produced as by-products in chlorine bleaching processes. 

Products and Uses Among the most toxic synthetic chemicals known. It is produced when certain organic compounds are burned. It is also a byproduct of the chlorine bleaching process of wood pulp to produce papers, diapers, and so... 

Industrial/Municipal Processes Dioxin-like compounds can be formed through the chlorination of naturally occurring phenolic compounds such as those present in wood pulp. The formation of CDDs and CDFs resulting from the use of chlorine bleaching processes in the manufacture of bleached pulp and paper has resulted in the presence of CDDs and... 

Miscellaneous. In ore flotation, sodium sulfite functions as a selective depressant. In textile processing, sodium sulfite is used as a bleach for wood (qv) and polyamide fibers and as an antichlor after the use of chlorine bleach. Synthetic appHcations of sodium sulfite include production of sodium thiosulfite by addition of sulfur and the introduction of sulfonate groups into dyestuffs and other organic products. Sodium sulfite is useful as a scavenger for formaldehyde in aminoplast—wood compositions, and as a buffer in chrome tanning of leather. 

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 ... 

Berthollet s chlorine bleach helped dress the world in sparkling white. Later it purified drinking water, saving lives around the world. His process solved two important problems, but it unwittingly created an unexpected one that came to light almost two centuries later. Only after modern chemists learned how to analyze and identify minute traces of chemicals... 

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. 

Synthetic organic chemists have simplified many processes, using catalysts to make useful chemicals in one step from basic raw materials such as propane. The gigantic paper and pulp industry has devised many new bleaching processes to replace traditional chlorine bleaching. 

ECF [Elemental chlorine free] A generic term for pulp-bleaching processes which use chlorine dioxide and other oxidants in place of elemental chlorine. See also TCF. 

Prenox A pulp-bleaching process using nitrogen dioxide and oxygen instead of chlorine. Developed by AGA, Sweden. 

Solvay (2) A pulp-bleaching process using chlorine dioxide, generated by reducing sodium chlorate with methanol. In 1962, 20 paper mills in the United States were using this process. See also Mathieson (1). 

---