Rapid analysis of heavy metals in the coal ash with laser-induced breakdown spectroscopy

In this study, laser-induced breakdown spectroscopy (LIBS) was applied for the qualitative elemental analysis of coal ash. The spectrum of the ordinary coal ash indicated that coal ash contains elements of Al, Fe, Cu, Ca, Mn, Ti and so on. Sulfates produced by the reaction of metal oxides in coal ash with the acid gases in the atmosphere are the main causes of haze-fog formation. To simulate the haze, eight solutions with different Pb concentrations were prepared and coal ash samples were soaked in solutions and then dried thoroughly. The spectra were obtained from these contaminated coal ash samples with the LIBS technique. To accurately identify the spectral lines of Pb in the spectrum, the spectrum of pure Pb were selected as a reference and the spectral lines of Pb were determined. At the same time, an internal standard method was used to quantitatively analyze the value of the component of Pb/Al with a calibration curve that had a linear correlation coefficient (R2) of 0.98648, which indicates rough estimation of Pb content can be achieved by the intensity of Pb in the spectrum. The results of the experiments show that LIBS technique can be employed for the rapid detection and analysis of metal elements in coal ash and provide a brand-new method for the detection of atmospheric environment based on the content of Pb.