水溶液中铬元素的激光诱导击穿光谱研究

Laser Induced Breakdown Spectroscopy of Chromium in Water Solution

以对工业废水或污水溶液中Cr元素的实时、定量检测为目标,实验研究了重铬酸钾(K2Cr2O7)水溶液中金属元素Cr的单脉冲激光诱导击穿光谱(LIBS)。研究了Cr元素LIBS信号的时间演化特性及脉冲激光能量对Cr元素LIBS信号的影响。通过测定Cr元素浓度(物质的量分数)在5×10-5～4×10-3区域内变化时425.44nm谱线处的强度,得到了Cr元素浓度与谱线强度的定标曲线。实验结果表明,本实验的最佳探测延时为1.28μs,最优脉冲激光能量值为120mJ。由定标曲线拟合结果得到Cr元素的检测限为6×10-6。研究结果表明,应用LIBS技术能够实时、定量检测水溶液中的重金属Cr元素,并且能够达到较好的检测限。

In order to obtain a method for real-time and quantitative detection of the chromium element in industrial wastewater or sewage solution, trace heavy metal element chromium in K2Cr2O7 solution is measured by laser induced breakdown spectroscopy （LIBS）. The temporal evolution property and the influence of the pulse laser energies on the LIBS signal of Cr element are investigated respectively. The spectrum intensity is measured. The calibration curve of the Cr element is obtained from the measurement of the Cr 425.44 nm spectral line intensities with the Cr concentration ranging from 5×10-5 to 4×10-3. The experimental results show that the best time delay for spectrum detection is 1.28 μs and the optimal pulse laser energy is 120 mJ. The LIBS detection limit of Cr in the solution is 6×10-6 obtained from the measured calibration curve. This study indicates that LIBS can be applied to the real-time, quantitative detection of Cr element in solution with a good detection limit.