| 摘要 |
Chlorine and chlorine dioxide are passed into water so that a substantial portion of the chlorine and substantially all of the chlorine dioxide are absorbed, and the water, which then contains chlorine and chlorine dioxide in the ratio from 1 : 1 to 1 : 4, is used in a later stage of a multi-stage process for bleaching cellulosic materials. The unabsorbed gases are scrubbed with liquor to be used in one of the earlier stages of the bleaching process so that the chlorine requirement of such stage is partly or completely met. The mixture of chlorine and chlorine dioxide is conveniently generated by reaction of sulphuric acid with sodium chlorate and sodium chloride. A pH value of 7 to 10 is preferably maintained during the bleaching stage by adding an alkali or alkaline salt. |
