Bleaching chlorine dioxide

A. Teder and D. Tormund, "Mathematical Model for Chlorine Dioxide Bleaching and its AppHcations," AiChE Symposium Series, No. 200, Vol. 76, American Institute of Chemical Engineers, New York, 1980, pp. 133—142. 

The commercial importance of this metal was first recognized in 1950s when its high strength/density ratios were found attractive in aerospace applications. The corrosion resistance in a variety of conditions led to its use in wet chlorine gas coolers for chlor-alkali cells, chlorine and chlorine dioxide bleaching equipment in pulp/paper mills, and reactor interiors for pressure acid leaching of metallic ores. The metal and its alloys were used in seawater power plant condensers, with over 400 million feet installed in application.65,66 The most commonly used alloys and their composition are given in Table 4.48. 

The normal lining construction consists of a membrane on the steel shell and one layer of acid brick in a resin mortar. The membrane materials used have been a silica filled latex rubber or, more recently, a silica filled urethane. Either of these membranes is installed by troweling it onto the steel shell. The mortars used have been polyester or vinyl ester based and are used in the back joints, bed joints, and side joints. That is, the brick are completely surrounded by the mortar, except, of course, for the face. The equipment in which this type of construction is used includes the chlorine dioxide storage tank, the chlorine dioxide generator spent acid tank, and the chlorine dioxide bleach tower. 

Wintzer, P. 1980. Enticklung und Trend der Chlordioxid-Bleiche mil iniegrierler Chlorat-Electrolyse fUr die Zellslojf-Indusirie (Developments and trends in chlorine dioxide-bleaching with an integrated chlorate electrolysis for the wood pulp industry), Chem. Ing. 52, Tech. 392-398. 

In paper industry jargon, chlorine dioxide bleaching is ECF bleaching (elemental-chlorine-free) and bleaching with oxygen species TCF bleaching (totally-chlorine-free). 

Gunnarsson, N. P-L, and S. Ljunggren. 1996. The kinetics of hgnin reactions during chlorine dioxide bleaching. Part I. Influence of pH and temperature on the reaction of l-(4, 4-dimethoxyphenyl) ethanol with chlorine dioxide in aqueous solution. Acta Chem. Scand. 50 422-431. 

G GeUerstedL E-L Lindfors, M Pettersson, D Robert. Reactions of Lignin in Chlorine Dioxide Bleaching of Kraft Pulps. Res Chem Intermed 21 441 56, 1995. 

M Ragnar. On the importance of the structural composition of pulp for the selectivity of ozone and chlorine dioxide bleaching. Nordic Pulp Pap Res J 16 72-79, 2001. 

Y Ni, GJ Kubes, ARP van Heiningen. Characterization of pulp demethylation during chlorine dioxide bleaching. Wood Sci Technol 29 87-94,1995. 

Chlorine dioxide Bleaching kraft paper and flour... 

Polyester cements were originally developed as grouting materials for brickwork in chlorine dioxide bleaching systems under the trade name of VitroplastThese products which are also used for the production of cultured marble and large pipes are discussed in detail in Chapters 6 and 7. 

In similar studies Frazer et al. (1956a, b) noted a drop in the a-tocopherol content of flour from 1.5 mg % to 0.2 mg %. They considered this loss to be of no nutritional import since even whole wheat bread will supply only a small percentage of the 15 mg % of tocopherol required by man daily (Sebrell and Harris, 1954). Mason and Jones (1958) noted that the total tocopherol content of Australian whole wheat dropped from 2.3 to 1.55 mg % in milling, and to 0.72 mg % after chlorine dioxide bleaching. 

Figure 14 Relative effectiveness of bromination and sodium hypochlorite in white water from a mill that uses chlorine dioxide bleached pulp. Note the performance of bromination and hypochlorite is similar on an active (CI2) basis and only 2 ppm are needed for significant kill.

Figure 20-16 A bleaching stage consists of prewashing, mixing for steam addition (temperature adjustment), mixing for chemical addition, pulp retention in a tower, and postwashing. The diagram is typical of a chlorine dioxide bleaching stage (Dj or D2) and shows only the pulp and chemical flows. Filtrate flows are not shown.

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