ZENG Mingguo, LI Yongsheng, ZHAO Yang, et al. Simultaneous determination of CoO and MoO3 in catalyst impregnation solutions by flow injection spectrophotometry[J]. CIESC Journal, 2017, (8): 3056-3063. DOI: 10.11949/j.issn.0438-1157.20170123.
ZENG Mingguo, LI Yongsheng, ZHAO Yang, et al. Simultaneous determination of CoO and MoO3 in catalyst impregnation solutions by flow injection spectrophotometry[J]. CIESC Journal, 2017, (8): 3056-3063. DOI: 10.11949/j.issn.0438-1157.20170123.DOI:
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)