Automatic Potentiotitrimetric Determination of Chloride in Desulfurizing System

The content of chloride in desulfurizing system was determined by automatic potentiometric titration using 0.05 mol·L-1 AgNO3 standard solution as titrant in a weakly acidic solution of pH 5, containing total ionic strength buffer. Soluble chloride in the sample was extracted with water. Interference of sulfite was eliminated by boiling the nearly neutral sample solution with H2O2 until ceasing of gas-bubbling. Methods of pretreatment of sample, and various parameters affecting the titration were studied and optimized. The proposed method was applied to the determination of chloride in desulfurizing samples of waste water, pasty liquor and gypsum, giving values of recovery and RSD′s (n=5) in the ranges of 95.7%-102.0% and 1.2%-5.9% respectively.