Charge Measurement
Analysis of the movement of suspended particles in an electric field provides information about the surface charge of pulp fibres and filler particles in papermaking. This technique, called micro-electrophoresis, tracks the migration of fine particles under a known voltage. Determining this mobility allows for the calculation of the zeta potential of the system.
Process Utility
Wet-end chemistry control relies on charge optimization to maximize the retention of fillers and sizing agents on the forming wire. By employing micro-electrophoresis, technicians can monitor the effects of cationic polymers and anionic trash on the stability of the pulp furnish. When the zeta potential approaches zero, the electrostatic repulsion between particles decreases, which promotes flocculation.
Managing these charge dynamics reduces the consumption of chemical additives and improves drainage rates on the paper machine.
Operational Limit
High electrical conductivity in the process water can restrict the precision of the measurements. Because the applied current generates heat in highly conductive environments, it can create convection currents that distort particle movement. Dilution of the sample with filtered process water is therefore necessary to obtain accurate results.
Correct interpretation of these values prevents the over-addition of retention aids and helps avoid deposit formation on the paper machine.
