Performance of an Automatic, On-Line Zeta Potential Instrument, 1991 Papermakers Conference Proceedings

A new zeta potential instrument automatically generates data descriptive of the electrostatic charge of the furnish, utilizing the streaming potential principle. The principle of operation consists in automatically forming a pad, pumping white water through it, and measuring the electrical charge across the pad. This value, plus the conductance and temperature, is used to calculate zeta potential, which is output to a CRT display. A comparison is made of data generated by the automatic instrument with that obtained by the microelectrophoretic measurement of cellulosic fines. Data taken with the automatic instrument is essentially linear, with incremental additions of cationic chemical, whereas microelectrophoretic data shows an extended cationic demand plateau. It takes much longer to reach electrokinetic equilibrium when the entire furnish is assessed, as opposed to only the fines portion. Data is also taken by the automatic instrument on softwood Kraft pulp of varying freeness. The slope varies as a function of freeness, with the steepest slope at the highest freeness.