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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。
Aiming at the real-time and quantitative detection of Cr in industrial wastewater or sewage solution, the single-pulsed laser-induced breakdown spectroscopy (LIBS) of metal Cr in aqueous potassium dichromate (K2Cr2O7) solution was studied experimentally. The time evolution of LIBS signal and the influence of pulsed laser energy on the LIBS signal of Cr element were studied. The calibration curve of Cr element concentration and spectral line intensity was obtained by measuring the intensity at the spectral line of 425.44 nm when the elemental concentration of Cr (mass fraction) was changed from 5 × 10-5 to 4 × 10-3. The experimental results show that the best detection delay of this experiment is 1.28μs and the optimal pulse laser energy is 120mJ. The detection limit of Cr element obtained from the calibration curve fitting is 6 × 10-6. The results show that the application of LIBS technology can real-time, quantitative detection of heavy metals in aqueous solution of Cr, and can achieve better detection limits.