粉煤灰中痕量汞的催化光度法测定

Determination of Trace Mercury in Fly Ash by Catalytic Spectrophotometry

在 p H3.5乙酸 -乙酸钠缓冲溶液中痕量汞 ( )对 K4[Fe( CN) 6 ]与 4 ,7-二苯基 -1 ,1 0 -邻菲 口罗啉 ( BPT)显色反应有催化作用 ,加入硫脲能提高其灵敏度 ,显色程度与 Hg( )量在一定范围内呈线性相关。借此建立测定痕量 Hg( )的分光光度法。实验表明 ,有色溶液的最大吸收波长为 535nm,摩尔吸光系数为 4 .5× 1 0 6 L·mol- 1· cm- 1 ,催化程度与 Hg( )量在 0 .0～ 2 .0 μg/ 50 m L范围内符合比耳定律 ,选择性较好。结合萃取分离 ,本法可用于测定粉煤灰中的痕量汞。

Trace Hg(Ⅱ)catalyzes chromogenic reaction of 4,7 diphenyl 1, 10 phenanthroline (BPT) with K 4[Fe(CN) 6] in a weak acid medium(pH 3.5 HOAc NaOAc buffer) has been studied. The addition of thiourea can further increase the sensitivity of the reaction and the chromogenic extent is linear with the concentration of Hg(Ⅱ). Based on this study, a spectrophotometric method for the determination of trace Hg(Ⅱ) was developed. The results show that the apparent molar absorptivity was 4.5×10 6 L·mol -1 ·cm -1 at 535 nm and Beer's law was obeyed for Hg(Ⅱ) in the range of 0.0～2.0 μg/50 mL. The relative standard deviation was less than 6 % and the recovery was 98.5 %～105.6% (n=6). Combined with solvent extraction, the method has been applied to the determination of trace Hg in fly ash.