Interactions between cationic starch and anionic trash of a peroxide-bleached TMP at different salt concentrations

The consumption of cationic starch of medium-charge density by dissolved and colloidally dispersed wood substances from a peroxide-bleached TMP was evaluated at different concentrations of a monovalent and a divalent ion, respectively. The consumed amount of starch was, in general, reduced upon an increase in salt concentration. By addition of the starch, destabilization of stable colloidal wood substances could be obtained. Addition of cationic starch was necessary to obtain destabilization at all evaluated concentrations of the monovalent ion, although only partial destabilization was reached at the highest ionic strength, 10(-1) mol/L. Complete destabilization was achieved at all evaluated concentrations of the divalent ion. However, at the highest concentration of the divalent ion, 10(-2)-10(-1) mol/L, the colloidal wood substances were already destabilized upon addition of the salt.