Monitoring of toxic elements present in sludge of industrial waste using CF-LIBS.

Industrial waste is one of the main causes of environmental pollution. Laser-induced breakdown spectroscopy (LIBS) was applied to detect the toxic metals in the sludge of industrial waste water. Sludge on filter paper was obtained after filtering the collected waste water samples from different sections of a water treatment plant situated in an industrial area of Kanpur City. The LIBS spectra of the sludge samples were recorded in the spectral range of 200 to 500 nm by focusing the laser light on sludge. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique was used for the quantitative measurement of toxic elements such as Cr and Pb present in the sample. We also used the traditional calibration curve approach to quantify these elements. The results obtained from CF-LIBS are in good agreement with the results from the calibration curve approach. Thus, our results demonstrate that CF-LIBS is an appropriate technique for quantitative analysis where reference/standard samples are not available to make the calibration curve. The results of the present experiment are alarming to the people living nearby areas of industrial activities, as the concentrations of toxic elements are quite high compared to the admissible limits of these substances.

Laser-induced breakdown spectroscopy for determination of uranium in thorium-uranium mixed oxide fuel materials.

Laser-induced breakdown spectroscopy (LIBS) has been developed for determining the percentage of uranium in thorium-uranium mixed oxide fuel samples required as a part of the chemical quality assurance of fuel materials. The experimental parameters were optimized using mixed oxide pellets prepared from 1:1 (w/w) mixture of thorium-uranium mixed oxide standards and using boric acid as a binder. Calibration curves were established using U(II) 263.553 nm, U(II) 367.007 nm, U(II) 447.233 nm and U(II) 454.363 nm emission lines. The uranium amount determined in two synthetic mixed oxide samples using calibration curves agreed well with that of the expected values. Except for U(II) 263.553 nm, all the other emission lines exhibited a saturation effect due to self-absorption when U amount exceeded 20 wt.% in the Th-U mixture. The present method will be useful for fast and routine determination of uranium in mixed oxide samples of Th and U, without the need for dissolution, which is difficult and time consuming due to the refractory nature of ThO(2). The methodology developed is encouraging since a very good analytical agreement was obtained considering the limited resolution of the spectrometer employed in the work.

Determination of thorium and uranium in solution by laser-induced breakdown spectrometry.

Laser-induced breakdown spectrometry (LIBS) has been successfully developed to quantify thorium (Th) and uranium (U) in solution using membrane-based filter paper as a sample support. The filter paper is easy to handle and the entire analysis process takes only a few minutes for each sample. The developed method provides a practical approach for fast and sensitive determination of actinides in aqueous solutions using LIBS. We obtained calibration curves for U and Th individually as well as as a mixture. We observed that the quantification of trace levels of U in a bulk amount of Th was not possible because of strong spectral interference from Th at the most intense lines of U, but traces of Th in a bulk amount of U could be determined. The concentrations of U and Th in unknown solutions were determined by use of LIBS, and these results agreed to within 4% and 2%, respectively, with the expected values. The limits of detection for Th and U were calculated from the experimental data and were in the range of a few parts per million by weight to a few tens of parts per million by weight.