作为温室气体的主要成分, CO2的排放控制有利于应对全球气候变暖以及生态环境变化, 对CO2的快速检测具有重要意义。 目前检测CO2的方法有滴定法, 电化学法, 气相色谱法, 红外吸收光谱法等, 但对应用于工业现场的在线监测还存在着不足。 激光诱导击穿光谱(LIBS)具有远程测量, 无需或仅需简单预处理, 多组分同步测量等优点, 本文提出将其应用于CO2在线监测, 期望发展适用于工业过程碳排放的在线监测技术。 利用质量流量控制器控制纯度为99.99%的CO2和N2配比形成不同CO2浓度的混合气体模拟烟气环境, 　经过混气瓶充分混合后送入密封样品池进行LIBS测量实验。 研究不同延迟时间下C247.86 nm和CN38.34 nm谱线的演化规律, 验证了等离子体形成过程中存在部分CO2分子解离反应生成CN分子, 在CO2定量分析时应考虑CN分子谱线的影响, 并获得同步测量C原子和分子谱线的最佳延迟时间为800　ns。 在此基础上, 由于等离子体演化过程中, 各种信息相互影响, 分析指标与多个测量参数存在关系, 综合考虑C原子、 CN碎片及修正高浓度影响下的自吸收效应, 采用多元回归分析方法建立了CO2定量分析曲线, 其拟合度R2和斜率分别达到了0.978和0.981, 结果表明相比单个指标直接定标, 该方法提高了定量分析模型的可靠性, 验证了LIBS技术快速测量CO2的可行性。

With the rapid development of economy and industrialization, global warming is becoming the most serious sensitive global climate issues, which causes the rising of sea level and many other negative effects. The cause of global warming is the emission of greenhouse gases and carbon dioxide is the main component of greenhouse gases. The control of CO2 emssion is beneficial to addressing gobal climate change and environmental degradation. Therefore, it’s important to develop a rapid detection of CO2 for accurate control. There are amounts of methods to detect CO2 at present, including titration, electrochemical method, gas chromatography, infrared absorption spectroscopy and so on, however, t they still have the deficiency for online monitoring in industrial field. laser induced breakdown spectroscopy (LIBS), which is developing rapidly in recent few decades, is a detecting technology with characteristics of time-saving and synchronous measuring of multicomponent. What’s more, there is no need for sample pretreating. To develop the online monitoring technique of CO2 emission in the industrial field, LIBS was employed to measure CO2 in this study. The mass flow controller was used to adjust the flow of high purity CO2 and N2 to obtain mixed gas with different CO2 concentrations. The mixed gas was firstly mixed in an air mixing chamber for thorough mixing and then sent to the sample cell for LIBS measurement. The evolution of C atomic spectral line and CN molecular band with different delay times were being studied, which demonstrated parts of CO2 react with air ambient to form CN molecular during the plasma generation, the CN molecular band should be taken into consideration for quantitative analysis, and the parameters were optimized for synchronous measurement of C line and CN band: 800 ns was the optimal delay time. During the plasma generation, many factors in the plasma may interact with others, the analysis index had close relationship wih serval measuring parameters. With the consideration of the effect of C, CN and the self-absorption in high concentration, multivariate calibration method was employed to establish calibration models of CO2. The results showed that the correlation coefficients R2 and the slope were 0.978 and 0.981, respectively. Compared with calibrated with single factor, the multivariate method improved the reliability of the model. What’s more, the feasibility of the application of LIBS to measure CO2 rapidly was proved.