The extent of anthraquinone (AQ) penetration into handcut Norway spruce chips as a function of cooking time was examined through the combined use of14C-label-led AQ and various wood sectioning techniques. The results indicated that in the initial stage of the cook, the AQ was deposited mainly at or near the chip surfaces in contrast to the alkali which penetrated to the chip core. With increasing cooking time, free and/ or combined AQ concentration at the transverse surface of the chips first decreased then increased both in this region and in the chip interior. This non-uniform distribution of AQ and alkali within the chips during the initial stage of pulping was also manifest by the Kappa number which increased significantly in proceeding from chip exterior to core.
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