Researching On The Raman Spectra Characteristics And Quantitative Analysis Of Compound Ammonium Salt

The laser Raman Spectroscopy was used to study on the Raman spectrum characteristics of the ammonium thiocyanate, ammonium sulfate and ammonium thiosulfate and the mixed ammonium brine solution of spectrum characteristics respectively. Combined theoretical analysis, discuss the Raman frequency shift and luminescence mechanism of three species ammonium salt. Quantitative research the anion concentration in the ammonium salt corresponds to peak intensity and peak area. The research results can give a valuable reference for coking enterprise in the quantitative detection compound ammonium salt.Using the laser stimulated the solution of ammonium thiocyanate, the results showed that the Raman peak of ammonium thiocyanate located at752cm"1, Raman frequency shift of water located at1650cm-1. The analysis result indicated the SCN-structure in the thiocyanate solution relates to Raman frequency shift.-S-C=N is often described as resonance structures by-S-C=N and S=C=N-.However, Raman spectroscopy demonstrated that the key C=S in thiocyanate solution does not exist. Therefore, the peak at752cm-1is belonged to-S-C=N, namely it was caused by stretching vibration peak of C=N. Peak intensities of ammonium thiocyanate enhanced with concentration increases. Raman peak intensity and concentration had linear relationship, also between peak area and concentration.Second, study on Raman spectra of ammonium sulfate and ammonium thiosulfate. Experimental results indicated that the ammonium sulfate Raman peak locates at982cm"1. Analysis that it was caused by the symmetrical stretching vibration of S-O key when stimulates the sulfate ion. Ammonium thiosulfate peak is located at997cm-1, caused by stretching vibration of S-S key. Peak intensity of ammonium sulfate and ammonium thiosulfate enhance with the concentration increases, peak area and concentration have positive correlation respectively.The correlation coefficient and coefficient of determination of ammonium sulfate between intensity and concentration wereO.99921,0.99824;also the coefficients between intensity and area were0.99933,0.99852,respectively. The correlation coefficient and coefficient of determination of ammonium thiosulfate between intensity and concentration were0.99933,0.99852;also the coefficients between intensity and area were0.99941,0.99869.Indicate that the linearity is very good between the Raman signal and ion concentration. Fitting Raman peak area and concentration was better than fitting Raman peak intensity and concentration.Use the same method to study on the composite ammonium salt and with the relationship between ion concentration and different Raman peaks to identify and quantitative analysis different ion concentrations in compound ammonium salts. When the excitation light irradiates mixing solution, three kinds of anions Raman peak locate at752cm-1,982cm-1,997cm-1respectively, the same as the three ammonium salts with independent measurements. Measure each compound ammonium salt solution Raman peak area and the corresponding anion concentration and do linear analysis. Results indicated that the Raman peak area of the thiocyanate ion and ion concentration fitting equation is S=5114.955C-225.077,Which S is the area,C is the concentration, the correlation coefficient R is0.9996, the determination coefficient R2is0.9992; the Raman peak area of the sulfate ion and ion concentration fitting equation is S=18830.967C+391.441,The correlation coefficient R is0.9948, the determination coefficient R2is0.9896; the Raman peak area of the thio-sulfate ion and ion concentration fitting equation is S=5393.393C+201.496, The correlation coefficient R is0.9968, The determination coefficient R2is0.9936.Through establish database of three different anions Raman peak area and the corresponding ion concentration, and establish theoretical data model so that the error measured is less than0.05mol/LSensitive Raman spectroscopy could be used to measure in ammonium thiocyanate, ammonium sulfate and ammonium thiosulfate of mixed solution. The result provided a valuable reference for identify and quantitative analysis ammonium salt in practical industrial production.