Modeling of non-process element balances in washing and bleaching of kraft pulp

Theoretical models that describe the equilibrium distribution of cationic and anionic solutes in cellulose fiber suspensions have been developed. The models are based on the Donnan equilibrium theory. They can be used for the prediction of the pH. the partition of ions between fiber phase aid external solution as well os the complexation equilibria in fiber-water suspensions. The models have been tested by metal ion sorption experiments as well as by washing and closed cycle bleaching experiments. preliminary results show that the models provide a strong basis for the further development of simulation applications that are to be used for the prediction of Non-Process Element balances in fiberline processes.