Electrolyte Pathway
Potentiometric measurement of pH in textile processing liquors requires a highly conductive and stable liquid connection between the reference electrode and the sample. A potassium chloride bridge provides this connection by utilizing a concentrated salt solution that minimizes liquid junction potentials. This specific salt choice ensures that the electrical current is carried almost equally by both anions and cations.
Reference Junction
The equitransferent mobility of potassium and chloride ions prevents the development of an electrical charge separation at the boundary of the test solution. If the ions moved at different rates, a spurious voltage would develop, corrupting the pH reading of the treatment bath. By maintaining high concentrations of potassium chloride, the bridge dominates the electrical conductivity at the junction, rendering other dissolved salts irrelevant.
Concentration Stability
Laboratory technicians must ensure that the salt solution remains saturated during continuous testing cycles to maintain signal accuracy. If the solution becomes diluted through contact with wet textile samples, the electrical conductivity decreases and the electrode starts to drift. Storing the sensor in a saturated potassium chloride solution between tests preserves the concentration gradient and extends electrode life.
Measurement Verification
Unstable liquid junctions lead to inaccurate acidity readings, which can cause uneven dye fixation on wool or cotton fabrics. Utilizing a potassium chloride bridge maintains the signal stability necessary for automated dosage controllers.
