Kraft pulp acid groups

Figure 6.1 The acid group content of pulps expressed as an ion exchange capacity as a function of kappa number (measure of lignin content) for Kraft and sulfite pulps.

Other Reactions In addition to the direct stabilizing effect of the uronic acid groups, the relatively high yield of hardwood kraft pulp is also due to the readsorption of xylan on the fibers (Fig. 7-35). After kraft pulping of softwood, the glucomannan remaining in the pulp still contains traces of... 

Because of its simplicity, the concept of Donnan equilibrium is an attractive approach for the modelling of fibre-ion interactions. However, despite its general success in many cases, the Donnan theory alone is not sufficient to describe the experimentally observed distributions. In those cases, it is necessary to use ion-specific complexation equilibria with the acidic groups as a part of the model to describe the observed phenomena satisfactorily. Such behaviour has been shown to exist, for example, with chemically modified highly charged fibres. An apparent systematic deviation in the ionic distribution from the predictions of the Donnan theory has also been noted with common oxygen-delignified kraft pulps, partly, but... 

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