Rapid Detection Of Cr And Pb In Liquids By Laser-induced Breakdown Spectroscopy

At present, the water heavy metal pollution is more and more serious. The traditionaldetection methods are slow, pretreatment and complex, they are difficult to meet the needsof modern society. Therefore, how to detect aqueous heavy metals quickly and efficientlyis becoming a hotspot research at home and abroad. In this paper, a new method has beenstudied to detect the heavy metals fast and in situ by laser induced breakdown spectroscopy(LIBS). Main research works are as follows:Firstly, the thesis begins with a brief background introduction of this work. Theresearch of the liquid matrix element detection and the research progress of LIBStechnology were introduced.Secondly, the LIBS experimental setup was built and optimized according to theparticularity of the solution detection. Potassium dichromate solution and lead nitratesolution were configured. As the research object, trace heavy metal element Cr and Pbwere measured by LIBS. The optimal observation line was established in this experiment,PbⅠ405.78nm and CrⅠ425.43nm were chosen to be the analytical lines.Again, the characteristics of the laser induced plasma in water have been investigatedwith potassium dichromate solution and lead nitrate solution samples in this work. Thetemporal evolution property、the cumulative frequency、the different repetition frequencyand the influence of the pulse laser energies on the LIBS signal of Cr and Pb element areinvestigated respectively. The experimental results showed that the best delay time is1280ns and3000ns and the optimal laser energy is120mJ and70mJ and the best cumulativefrequency is15times30times and the optimal repetition frequency is1Hz and2Hz forthe solution of K2Cr2O7and Pb(NO3)2respectively in this experiment.Then, under the best parameters of the experiment, the strength of the directcalibration method, internal standard method and partial least squares method are takeninto the calibration of Cr and Pb element in sample. It indicated that laser-inducedbreakdown spectroscopy is suitable for rapidly component quantitative analysis in solutionwith receptible applicability.Finally, the research conclusions were summarized, and some suggestions on thefurther work and hope were presented.