OPTIMIZING PAPER-MACHINE PERFORMANCE THROUGH ELECTROKINETIC MEASUREMENT

Electrophoretic mobilities (zeta potential) have been measured for sto cks and furnishes at several sites at Australian Paper The zeta potent ial distributions were measured by Doppler Electrophoretic Light Scatt ering Analysis using a Coulter DELSA 440 instrument. Samples exhibited both simple monomodal and complex polymodal charge distributions, wit h mean zeta potentials normally anionic and falling in the range from zero to -50 mV. For raw pulps, zeta potential distributions were parti cularly influenced by the degree of washing. The introduction of paper making additives usually, but not always, changed the mean zeta potent ial and, in some cases, also the complexity of the distribution. Exten ded monitoring of key stocks for zeta potential can detect subtle chan ges in quality, such as an increase in anionic trash, that are not rea dily detected by other means. It is concluded that the DELSA 440 is a useful instrument for characterizing zeta potential distributions of c olloidal papermaking furnishes.