Charge Measurement
An analytical determination of dissolved anionic substances in a papermaking slurry helps optimize chemical addition rates. The cationic demand of a pulp suspension indicates the quantity of positively charged polymer required to neutralize these dissolved and colloidal materials. This value is measured in milliequivalents per liter using a charge analyzer.
Chemical Balance
Wet end chemistry operates most efficiently when the overall electrical charge of the system is near the point of zero charge. When the cationic demand of the system is too high, added chemicals such as retention aids and strength resins cannot bind effectively to the negatively charged wood fibers. The excess anionic material, often called anionic trash, instead reacts with these expensive additives, neutralizing their active sites before they can perform their intended function.
Measuring this property allows the papermaker to adjust the dosage of coagulants, ensuring the functional polymers remain free to interact with the pulp fibers.
Process Control
Rapid changes in the raw material mix or recycled water quality can disrupt the ionic equilibrium of the headbox. Monitoring the cationic demand prevents issues such as deposit formation on the paper machine and poor drainage through the forming wire. A stable charge profile improves both paper formation and machine runnability.
