A novel and simple method for determining the cationic demand of suspensions using chromophoric labeled cationic polymers

A cationic demand (CD) is a very useful indication for determining the opti mum dosage rate of cationic flocculants to the suspensions. Polyelectrolyte titration has been most often used to determine a CD. This method works ve ry well when the ionic strength of sample is low, but is accompanied by the serious errors when the ionic strength is higher than that corresponding t o 20 mM monovalent, 2 mM divalent, or 0.2 mM trivalent ions because of no o ccurence of the end point of titration. Therefore, it is difficult for the conventional method to be applied to the industrial suspensions such as pap ermaking stock and industrial waste water. Therefore, a novel method using chromophoric-labeled cationic polymer which can be applicable to the sample with high ionic strength has been developed. (C) 1999 Elsevier Science B.V . All rights reserved.