Delignification of Spruce Sawdust with Chlorine Dioxide

Production of sawdust at mills is increasing, and numerous attempts have been made to find an economic use for such byproducts. One-stage delignification of spruce sawdust gives a potentially useful pulp; however, 68 percent chlorine dioxide (based on the wood) is consumed. A multistage laboratory procedure is described involving pretreatments with dilute H2SO4 and dilute NaOH followed by two delignification treatments with chlorine dioxide at atmospheric pressure and 100?C with an intermediate alkali stage. The amount of chemical consumed was reduced to 25 percent. Pulp yields are 45 percent with alpha contents of 77-87 percent. Degree of polymerization values ranged from 1400 to 2000. The pulps can be used for making lacquers or plastics.

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