Processing Of Square Wave Voltammetry Curve In Electrochemical On-line Monitoring Based On Wavelet Analysis

Spent fuel dry reprocessing is considered to be one of the unique advantages of spent fuel reprocessing technology.It is necessary to on-line monitor the spent fuel chemical system during the dry reprocessing.Square wave voltammetry,as an online electrochemical monitoring method,can obtain the progress of electrochemical reactions in real time.However,the electrochemical curve presented by a complex chemical system requires complex mathematical description.Wavelet analysis is used to process electrochemical signals,which can achieve the purpose of fast and accurate qualitative analysis.Thus,quantitative analysis using wavelet analysis is expected to realize online monitoring of spent fuel reprocessing.The quantitative relationship of single component,binary component and multi-component systems in Li Cl-KCl molten salt were carried out using La(Ⅲ),Sm(Ⅲ),Pr(Ⅲ),Ho(Ⅲ),Ce(Ⅲ),Dy(Ⅲ),Y(Ⅲ),Nd(Ⅲ),Zr(Ⅳ)and Yb(Ⅲ)as research objects.By constructing a wavelet analysis model to analyze the square wave voltammetry curve of the above systems,the standard working curves of the target ions were obtained,and the determination coefficient of the standard working curves were calculated.The errors between the theoretical concentration derived from the wavelet analysis model and the actual concentration were also analyzed.The details are as follows:(1)A wavelet analysis model suitable for Li Cl-KCl molten salt system was constructed.The wavelet analysis model was established based on one-dimensional wavelet decomposition and third-order spline function peak resolver.The typical square wave voltammetry curve was used to simulate those of single component and binary component systems.According to the smallest error,the optimal wavelet function Daubechies2 wavelet was selected.The maximum resolution RS of overlapping peaks that can be separated by the model was obtained as 0.357.(2)The square wave voltammetry(SWV)curve of single component system was analyzed by wavelet analysis model.The numbers of transferred electrons of La(Ⅲ),Sm(Ⅲ),Pr(Ⅲ),Ho(Ⅲ),Ce(Ⅲ),Dy(Ⅲ)and Y(Ⅲ)were calculated by SWV,and the standard working curves related to the peak current and ion concentration were drawn.The peak shape of SWV curve was corrected using the wavelet analysis model,and the coefficient of determination R-square(COD)presented by the fitted straight line is closer to 1.The results show that the standard working curve given by the wavelet analysis model has higher linear correlation.The overlapping peaks of SWV curves of variable valence ions Nd(Ⅲ)and Zr(Ⅳ)were resolved,and the accurate peak potential of intermediate valence ions was given.(3)The electrochemical behaviors of Pr(Ⅲ)and Ho(Ⅲ),Sm(Ⅲ)and Yb(Ⅲ),Sm(Ⅲ)and Zr(Ⅳ)binary systems were studied by SWV and CV and the reduction peak potentials were confirmed.The SWV curves of binary system were analyzed by wavelet analysis model.The overlapping peaks of square wave voltammetry curves were resolved.The working curves of peak current and concentration were drawn.The standard working curves of target ions under the interference of other ions were measured.(4)The electrochemical behavior of multicomponent systems with Pr(Ⅲ),Ho(Ⅲ),Zr(Ⅳ),Sm(Ⅲ)and Yb(Ⅲ)was studied by SWV and CV electrochemical methods.The SWV curves of multicomponent systems were analyzed by wavelet analysis model.According to the standard working curve and SWV peak current,the predicted concentration of the target ion was calculated.Compared with the actual concentration,the predicted concentration error was found to be within an acceptable range.The wavelet analysis model has good analytical capabilities.