Bleaching sequences

Caro s acid is effective ia delignifying wood pulp (qv) made by chlorine-free bleaching sequences. When conditions are carefully controlled, the mechanical properties of the final paper (qv) are not impaired. These processes were developed ia the 1980s and commercialized ia the 1990s (68). 

Fig. 29. CEDED pulp bleaching sequence A, delignifying, and B, brightening stages.

Further research directed toward optimizing bleach sequences, as well as development of biotechnologies to produce other enzymes that can directly delignify pulps with high specificity of action, can be expected. 

Sulfite pulping, 27 22-23, 4 45 Sulfite pulps, bleaching sequences used for, 27 32t... 

Kraft mill using 100% chlorine dioxide New and old wood pulp bleaching employing various bleach sequences Coastal fish community Mesocosm and fish biomarker tests High levels of mortality and low embryo quality Elemental chlorine containing bleach sequence, CEHDED was the most toxic Sandstrom, 1994 [25] Tana et ah, 1994 [26]... 

A large variety of conditions and combinations are used, some of them involving sodium peroxide and/or ozone stages (not shown here). Kraft pulps typically require more extensive bleaching (Sequences A and B) than sulfite pulps (Sequence C) (cf. Table 8-2). 

In 1958, a new intermediate in the bleaching sequence of rhodopsin was discovered, the liquid air illuminated rhodopin [93]. This red-shifted transient (Amax =543 nm) could be observed when cattle rhodopsin was irradiated in aqueous-glycerol... 

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