碱熔-共沉淀富集分离-电感耦合等离子体原子发射光谱法测定钒钛磁铁矿中痕量钪

用过氧化钠-氢氧化钠混合熔剂在750 ℃的马弗炉中将钒钛磁铁矿试样熔融,再用沸热的三乙醇胺(1+9)浸取熔块,使铁、钛、铝与三乙醇胺络合进入溶液,钒也以含氧酸盐形式进入溶液,向溶液中加入3 mL 10 g/L氯化镁溶液生成氢氧化镁沉淀,溶液中痕量钪则与氢氧化镁共沉淀从而与基体溶液中其他元素分离。过滤沉淀后,采用沸热的盐酸(1+1)溶解沉淀,以Sc 363.075{92} nm作为分析谱线,建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定钒钛磁铁矿中痕量钪的分析方法。实验表明:氢氧化镁共沉淀法可将钪与样品中干扰元素(铁、钛、钒、铬、钠、硅和铝等)分离,避免了基体的干扰。在选定的实验条件下,钪的质量浓度在0.050～2.00 μg/mL范围内与其发射光谱强度呈良好的线性关系,校准曲线线性相关系数r为0.999 9,方法检出限为1.5 μg/g,定量限为5 μg/g。方法用于钒钛磁铁矿样品中钪的测定,结果的相对标准偏差(RSD,n=6)为0.58%～2.3%,加标回收率为96%～103%,测定结果与分光光度法的测定结果一致。

Determination of trace scandium in vanadium-titanium magnetite by inductively coupled plasma atomic emission spectrometry combined with alkali fusion and co-precipitation enrichment separation

The vanadium-titanium magnetite sample was fused in muffle furnace at 750 ℃ with a mixed flux of sodium peroxide and sodium hydroxide. Then the melt was leached with boiling triethanolamine(1+9). Iron, titanium and aluminum could complex with triethanolamine and were transferred into the solution. Meanwhile, vanadium also entered the solution in the form of oxysalt. 3 mL of 10 g/L magnesium chloride solution was added to form magnesium hydroxide hydroxide precipitate. During this process, trace scandium in the solution was co-precipitated with magnesium hydroxide, realizing the separation from other elements in the matrix solution. After filtration, the precipitate was dissolved with boiling HCl (1+1). An analysis method for the determination of trace scandium in vanadium-titanium magnetite by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established with Sc 363.075{92} nm as analytical line. The results showed that the method of magnesium hydroxide co-precipitation could separate scandium from interfering elements (iron, titanium, vanadium, chromium, sodium, silicon and aluminum) in the sample, avoiding the interferences of matrix. Under the selected experimental conditions, the emission spectral intensity of scandium had a good linear relationship with its mass concentration in the range of 0.050-2.00 μg/mL. The linear correlation coefficient (r) of the calibration curve was 0.999 9. The limit of detection of the method was 1.5 μg/g, and the limit of quantification was 5 μg/g. The proposed method was applied for the determination of scandium in vanadium-titanium magnetite samples. The relative standard deviations (RSDs, n=6) were 0.58%-2.3%, and the recoveries were 96%-103%. The determination results were consistent with those obtained by spectrophotometry.