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当天然水中含有大量正磷酸盐和聚磷酸盐时,硫酸根的测定将受到严重干扰。本文根据磷酸锰,聚磷酸锰在pH=10—11时,与二氧化锰产生共沉淀的原理,来消除上述干扰。并用静态离子交换法除去残留的二价锰离子和钙、镁离子。然后以Ag_2S—PbS压膜铅电极为指示电极,用3×10~(-3)M高氯酸铅标准溶液在75％酒精体系中进行电位滴定。试验表明:本法精密度和准确度均比重量法好,而且测定下限低,方法简单快速。解决了长期来含磷酸盐的循环冷却水中硫酸根含量难以测定的问题。
When natural water contains a large amount of orthophosphate and polyphosphate, the determination of sulfate will be severely disrupted. According to the principle of manganese phosphate and manganese polyphosphate co-precipitated with manganese dioxide at pH = 10-11, the above interference is eliminated. And use the static ion exchange method to remove residual divalent manganese ions and calcium and magnesium ions. Then the Ag 2 S-PbS lead electrode was used as the indicator electrode, and titration was carried out in a 75% alcohol system using 3 × 10 -3 M lead perchlorate standard solution. Tests show that: The method of precision and accuracy are better than the weight method, and the lower limit of determination, the method is simple and fast. Solve the long-term phosphate-containing circulating cooling water sulfate content difficult to determine the problem.