基于流动注射光度法同时测定催化剂浸渍液中CoO/MoO3

基于Mo（Ⅵ）-抗坏血酸、Co（Ⅱ）-KSCN反应体系和流动注射光度法，建立了一个全新的催化剂浸渍液中超高浓度CoO/MoO₃的同时测定系统。研究发现：Co（Ⅱ）与KSCN络合物是由K₂Co（SCN）₄和K₄Co（SCN）₆构成，利用后者可定量Co（Ⅱ）；Co（Ⅱ）对Mo（Ⅵ）-抗坏血酸反应有抑制作用，会干扰Mo（Ⅵ）测定；本研究利用Co（Ⅱ）的抑制作用，人为在测Mo（Ⅵ）的显色剂中加入一定量的硝酸钴，解决了该干扰问题。另外，对测定Co（Ⅱ）/Mo（Ⅵ）用的显色剂中的成分及浓度、进样体积、反应温度等相关影响因素进行了优选，得到的结果是：测定Mo（Ⅵ）的显色剂由15%（质量分数）抗坏血酸、10 g·L^-1硝酸钴（以CoO计）及0.1 mol·L^-1硫酸组成，测定Co（Ⅱ）的显色剂由37.5% KSCN、0.1 mol·L^-1 NaAc-HAc（pH 5.8）组成；MoO₃和CoO的测定范围分别为10~100 g·L^-1和5~50 g·L^-1，检出限分别为2.1 g·L^-1和1.3 g·L^-1，RSD<1.2%（n=11），回收率为98%~104%，分析速度为20样/小时。

Simultaneous determination of CoO and MoO3 in catalyst impregnation solutions by flow injection spectrophotometry

Based on flow-injection analysis (FIA) and reaction systems of Mo(Ⅵ)-ascorbic acid and Co(Ⅱ)-KSCN, a new FIA system was proposed for simultaneous determination of high-concentration CoO/MoO₃ in impregnation solutions. It was found that reaction products of Co(Ⅱ) and KSCN were K₂Co(SCN)₄ and K₄Co(SCN)₆, which the latter can be used to quantitate Co(Ⅱ). Co(Ⅱ) inhibitory effect on reaction system of Mo(Ⅵ)-ascorbic acid interfered with the determination of Mo(Ⅵ). Such Co(Ⅱ) interference was resolved by adding cobalt nitrate in the chromogenic agent for Mo(Ⅵ) measurement. In addition, testing conditions were optimized for various factors such as constituents and concentrations in chromogenic reagents for determining Co(Ⅱ) or Mo(Ⅵ), sampling volume and reaction temperature. The chromogenic agents for testing Mo(Ⅵ) were consisted of 15% (mass) ascorbic acid, 10 g·L^-1 cobalt nitrate (calculated by CoO) and 0.1 mol·L^-1 sulfuric acid, whereas those for testing Co(Ⅱ) were consisted of 37.5% (mass) KSCN and 0.1 mol·L^-1 NaAc-HAc (pH 5.8). The detection ranges of MoO₃ and CoO were in 10-100 g·L^-1 and 5-50 g·L^-1, and the detection limits for MoO₃ and CoO were 2.1 g·L^-1 and 1.3 g·L^-1, respectively. Relative standard deviation was less than 1.2% (n=11), recovery was in range 98%-104%, and the analysis rate was 20 samples per hour.