Research On Analysis Method Of Heavy Metals In Oily Sludge Based On Laser Induced Breakdown Spectroscopy

As an indispensable resource in life,petroleum produces a large amount of oily sludge from mining to use,which contains a lot of toxic substances,especially heavy metals in oily sludge,which will cause serious harm to human health and the environment.Therefore,this research starts from the demand for quantitative analysis and risk estimation of heavy metals in oily sludge,and establish a method for rapid quantitative analysis of heavy metals in oily sludge based on laser induced breakdown spectroscopy(LIBS)combined with chemometrics and a method for estimating potential environmental risks to achieve accurate and rapid detection of heavy metals in oily sludge,which is an environment for heavy metals in oily sludge areas Pollution early warning and prevention provide theoretical basis and technical support..The main research contents are as follows:(1)Taking oily sludge as the research object,a quantitative model for the determination of heavy metal elements in oily sludge based on the LIBS combined with WT-RF model was constructed.First,optimize the LIBS laser energy based on the signal-to-background ratio.Secondly,study the impact of different preprocessing methods(normalization,standard normal transformation and wavelet transformation)on the performance of the RF model.Finally,the RF calibration model and standard curve method of LIBS based on the optimal preprocessing method are established.Collect spectral information of heavy metal elements in oily sludge.The results show that the performance of the LIBS-based WT-RF model is more reliable.The RMSEP of the Cu,Zn,Cr,and Pb prediction sets are 0.0288,0.0103,0.0309,and0.0330,and the R_P~2are 0.9587,0.9605,0.9589,and 0.9570.It can provide a new method for quantitative analysis of heavy metals in oily sludge.(2)Taking oily sludge as the research object,a method for the analysis of heavy metal content in oily sludge based on the importance of variables based on LIBS combined with WT-VIRF was constructed.First,on the basis of wavelet transform processing LIBS full-spectrum data,the optimal threshold of variable importance and model parameters are selected and optimized.Secondly,based on the optimal parameters,the quantitative analysis models of metals in the oily sludge of PLS,RF and LS-SVM were constructed respectively.The results show that compared with PLS and LS-SVM,the RF model has the highest accuracy.The RMSEP of the Cu,Zn,Cr,and Pb prediction sets are 0.0271,0.0074,0.162,and0.0245,and the R~2_Pare 0.9740,0.9665,0.9750,and 0.9600.After the variable importance is extracted,WT-VIRF analysis model has less time than full-spectrum modeling.It is a method that can accurately and quickly analyze the content of heavy metals in oily sludge.(3)Taking the pollution index value and potential ecological risk of heavy metals as the research object,construct an analysis method of LIBS combined with WT-RF model to analyze Nemeiro pollution index and potential ecological risk index index.First,according to Nemeiro index method and potential risk index method to obtain P_nvalue and RI value.Secondly,optimizing model parameters are selected on the basis of wavelet transform,and the P_nand RI index analysis model of RF based on LIBS is constructed.The results show that the MRE of Pn and RI in the prediction set are 8.67%and 8.23%,and the R~2_Pare 0.9745and 0.9730,respectively.The risk estimation results judged by LIBS combined with WT-RF and P_nand RI are consistent with XRF,which are heavy metals in oily sludge areas.Risk estimation provides a new way of thinking.