高浓度∑Fe对硝酸银滴定法测定Cl-干扰的消除

Elimination of High Total Iron Ion Concentration in Determining Chloride Ion with Silver Nitrate Titration

采用硝酸银滴定法测定含高浓度铁离子溶液中的Cl-时,需要调整pH到6.5～10.5,产生氢氧化铁与氢氧化亚铁沉淀,影响滴定终点的判定,导致分析结果不准确.本研究在含不同高铁浓度模拟溶液中加入氢氧化铝胶体洗涤出铁离子,再用硝酸银滴定法分析Cl-浓度,结果显示在Cl-浓度20 mg/L时,相对偏差小于5％,浓度为200 mg/L时,相对偏差最大为1.03％,并把该方法应用在分析花岗岩铀矿浸出液中的Cl-浓度,与采用选择氯离子电极法分析结果对比,结果表明了这两种方法的分析结果相差不大.因此该方法消除高铁对硝酸银滴定法分析氯离子是可行的.

Using silver nitration determine chloride ion in solution containing high concentration of total iron ion, the pH value in the solution must be adjusted to the range from 6.5 to 10.5, appearing ferric hydroxide and ferrous hydroxide, resulting in the end point of titration to be misjusted, affecting finally accuracy of the result. The experiments were conducted to study the elimination of different high iron ion concentration in simulated solution by aluminum hydroxide colloid, and then determinate the chloride ion with silver nitrate titration. The results show that relative deviations of determined solutions with chloride ion concentration of 20 mg/L and 200 mg/L were less than 5 % and 1.03 %, respectively. The method was applied to analysis the Cl- concentration in the leachate of granite, compared with chloride anion selective electrode, there was little difference. So this method, eliminating the high iron ion is workable to determinate chloride ion with silver nitrate titration.