罗丹明6G共振光散射法测定废水中铊

在硫酸介质中, 痕量铊(Ⅲ)与碘化钾反应生成I₃^-, I₃^-与罗丹明6G形成1∶1缔合物, 可导致共振光散射明显增强, 据此建立了共振光散射测定痕量铊的新方法。考察了它们的光谱特征:罗丹明6G溶液的共振荧光峰波长为540 nm, (Rh6G-I₃)n缔合微粒共振散射峰波长为330、420、580 nm。通过条件试验确定0.4 mL 0.2 mol/L硫酸作为反应介质、0.1 mol/L KI溶液用量为0.4 mL、1.0×10^-4 mol/L罗丹明6G 溶液用量为0.4 mL、反应时间为5 min。进一步考察发现, 在580 nm波长, 共振散射光强度增加值与溶液中铊浓度呈线性关系, 方法的线性范围为0.005～0.10 mg/L, 检出限为0.001 2 mg/L。方法应用于工业废水中铊含量的测定, 结果与ICP-MS法的对照结果基本一致, 相对标准偏差(RSD, n=6)为1.8%～3.2%。

Determination of thallium in wastewater by resonance light scattering method with Rhodamine 6G

In sulfur acid, trace thallium reacted with potassium iodide and generated I₃^- to form complex (1∶1) with Rhodamine 6G, resulting in significant enhancement of resonance light scattering. Accordingly, a novel method for the determination of trace Tl by resonance light scattering was developed. The spectrum characteristics were investigated: the resonance fluorescent peak of Rhodamine 6G was at 540 nm and the resonance fluorescent peaks of (Rh6G-I₃)_n complex particles were at 330, 420, 580 nm. Through condition test, it was determined that 0.4 mL of 0.2 mol/L sulfur acid was used as the medium, 0.4 mL of 0.1 mol/L KI solution and 0.4 mL of 1.0×10^-4 mol/L Rhodamine 6G was used, and the reaction time was 5 min. Through further investigation, the intensity increment of resonance scattering light showed linear relationship with Tl  at 580 nm. The linear range was 0.005-0.10 mg/L. The detection limit was 0.001 2 mg/L. The proposed method was applied to the determination of Tl in industrial wastewater, whose results were basically consistent with those of ICP-MS. The relative standard deviation (RSD, n=6) was 1.8%-3.2%.