固相萃取-电感耦合等离子体质谱法测定钢铁冶炼工业废水中铊

准确测定钢铁冶炼工业废水中铊,对钢铁冶炼排出的工业废水进行源头监测和控制铊污染具有重要意义。因钢铁冶炼工业废水盐分较高且铊含量较低,基体效应较为显著,故实验以γ-氨乙基氨丙基三甲氧基硅烷(KH792)改性纳米二氧化硅材料作为吸附剂,用固相萃取技术对铊离子进行分离富集,以2.0 μg/L ¹⁰³Rh作为内标,²⁰⁵Tl作为检测对象,建立了电感耦合等离子体质谱法(ICP-MS)测定钢铁冶炼工业废水中铊的方法。优化后的固相萃取条件如下:吸附pH值为8.5,吸附时间为15 min,样品体积为40 mL,吸附速率为1.5 mL/min,用5.0 mL 1.0 mol/L硝酸以0.5 mL/min的速率进行洗脱,富集倍数为8。在优化的实验条件下,在铊的质量浓度为0.10~10.0 μg/L范围内,以铊质量浓度为横坐标,铊信号强度与铑内标元素强度的比值为纵坐标,绘制校准曲线,其线性相关系数为0.999 9。检出限为0.002 3 μg/L,定量限为0.007 7 μg/L。将实验方法应用于钢铁冶炼工业废水中铊的测定,结果的相对标准偏差(RSD,n=7)为0.55%~2.8%,加标回收率为93%～101%。将实验方法应用于模拟钢铁冶炼工业废水中铊的测定,测定值与理论值基本一致。

Determination of thallium in industrial wastewater from steel smelting by inductively coupled plasma mass spectrometry with solid phase extraction

The accurate determination of thallium in industrial wastewater from steel smelting is of great significance for monitoring the source of steel smelting wastewater and controlling thallium pollution. Since the content of thallium in the wastewater from steel smelting industry was usually very low and the matrix effect was significant, thallium ions were separated and enriched by solid phase extraction (SPE) using γ-aminoethyl aminopropyl trimethoxysilane(KH792) modified nano-silica as the adsorbent. 2.0 μg/L ¹⁰³Rh was used as internal standard and ²⁰⁵Tl was selected as the detection object. A method for the determination of thallium in industrial wastewater from steel smelting by inductively coupled plasma mass spectrometry (ICP-MS) was established. The optimal SPE conditions were obtained as follows: the adsorption pH was 8.5; the adsorption time was 15 min; the sample volume was 40 mL; the adsorption rate was 1.5 mL/min; the elution was conducted with 5.0 mL of 1.0 mol/L nitric acid at rate of 0.5 mL/min; the enrichment factor was 8. Under the optimized experimental conditions, the calibration curve was plotted using mass concentration of thallium as x-coordinate and the ratio of signal intensity between thallium and internal standard as y-coordinate. The linear range for mass concentration of thallium was in range of 0.10-10.0 μg/L. The linear correlation coefficient was 0.999 9. The limit of detection was 0.002 3 μg/L, and the limit of quantification was 0.007 7 μg/L. The proposed method was applied for the determination of thallium in industrial wastewater from steel smelting. The relative standard deviations (RSD, n=7) of determination results were 0.55%-2.8%, and the recoveries were between 93% and 101%. The experimental method was applied to the determination of thallium in the simulated wastewater of steel smelting industry, and the found results were basically consistent with the theoretical values.