粉煤灰中痕量汞的催化光度法测定

在 p H3.5乙酸 -乙酸钠缓冲溶液中痕量汞 ( )对 K4Fe( 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。

Determination of Trace Mercury in Fly Ash by Catalytic Spectrophotometry

Trace Hg (Ⅱ)catalyzes chromogenic reaction of 4, 7-diphenyl-1, 10-phenanthroline (BPT) with K4 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 × 106 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 ％～105.60％ (n=6). Combined with solvent extraction, the method has been applied to the determination of trace Hg in fly ash.