亚铁法测定HNO_3-H_2C_2O_4混合液中的NO_3^-

DETERMINATION OF NO_3^- CONCENTRATION IN HNO_3-H_2C_2O_4 MIXED SOLUTION WITH FERROUS-SPECTROPHTOMETRIC METHOD

对测定TRPO流程H2 C2 O4反萃液中的NO3- 的分析条件进行了研究。在H2 SO4介质中 ,Fe2 +与NO3- 作用 ,定量释放出NO ,并立即同过量Fe2 +反应生成有色的亚硝酰配合物 ,利用这种性质用分光光度法或容量法测定NO3- 浓度。实验结果表明 :在氨磺酸存在下 ,质量比R(NO2 - /NO3- ) =3和R (C2 O42 - /NO3- ) =1 90时 ,对NO3- 的测定无影响。分光光度法测定NO3- 的检测下限为 0 1mg/L ,相对标准偏差为 3% ,重加回收率为 97%～ 1 0 3%。

The determination of NO 3 - concentration in H 2C 2O 4 stripping solution in TRPO process is studied. In H 2SO 4 solution, Fe 2+ reacts with NO 3 - and NO is liberated quantitatively. NO reacts with excess Fe 2+ immediately to form a colored nitrosyl complex which can be determined using spectrophtometric method. In the presence of sulfamic acid, determination of NO 3 - concentration is not affected with R (NO 2 -/NO 3 -) =3 and R (C 2O 4 2- /NO 3 -)=190. The minimum detection limit of NO 3 - concentration is 0.1 mg/L, the relative standard deviation of the method is 3%, the recovery of added standard sample is 97%～103%.