Determination Of Mercury In Environmental Waste Water

Cold atomic absorption spectrometry, UV spectroscopy, fluorescence spectroscopy wereused in this study.The concentrations of mercury in wastewater was determined by threemethods. The sample pre-treatment method of mercury was selected from nitric acid added,bromate-bromide digestion, potassium permanganate-persulfate method (near boiling heatmethod) and potassium permanganate-persulfate method (boiling method). The best methodof digestion mercury sample was confirmed.Comparing the results of cold atomic absorption method with the known concentrationof mercury, the pre-treatment method of the direct adding nitric acid is suitable for coldatomic absorption method. The relative standard deviation was0.070and the average relativedeviation of2.3%. By comparing with the mercury concentrationa dded, samplespre-treatment method of mercury was the direct adding nitric acid and the combination ofmercury ions and the reaction of4-hydroxy-ethoxy ethylamine-1,8-naphthalimide wasused in UV absorption spectrometry. With the mercury ion concentration increases, themaximum absorption value decreases and the concentration of mercury ions with themaximum absorption had the linear correlation within the0–0.5μg/L. The regressionequation of working curve: A=-0.055C+0.1533(C in units of μmol/L).The correlationcoefficient R2=0.993. The detection limit of the method was8.5μg/L. The recovery was95%to103%, relative standard deviation was0.14and the average relative deviation was4.4%. The potassium bromate–bromide digestion was selected to pre-treat samples ofmercury in fluorescence spectrometry. With the increasing concentration of mercury ions, thefluorescence intensity of fluorescent compound4–etermin-ethoxy ethylamine-1,8–naphthalimide gradually decreased and the linear correlation within the concentration ofmercury ion with maximum fluorescence intensity had the linear correlation within0–0.5μg/L range. The regression equation of working curve is: IF=-179.87C+124.17(C unit is μmol/L), correlation coefficient R2=0.9961. The detection limit was3.5μg/L. The recovery of was97%to102%and,the standard deviation was0.20and the average relative deviation was6.5%.Cold atomic absorption method has the lower limit of detection for mercury ions,0.01μg/L, so more suitable for the determination of mercury in water samples or other samples oftrace mercury. Fluorescence spectroscopy and UV absorption spectroscopy had highsensitivity and good recovery (98.3%and100.1%), so they more suitable for thedetermination of a higher precision required and higher levels of mercury. Thus, these threemethods can be used to etermine samples with low and high concentration of mercury ionsexactly and rapidly.