ABSTRACT
Turkey is the leading country in the world in terms of boron production and sale. Increasing boron production goes along with an increasing generation of boron wastes. The pollution of the soil and the air around the waste piles, as well as the occupation of several square kilometers of ground, are major environmental problems. It is, therefore, very important to make use of the wastes to both protect the environment and create revenue. This work presenteda road map for fast screening of boron waste for critical elements followed by determination of the elements using small footprint low power instrumentation. The sample preparation was kept to a minimum. A procedure that allowed an assessment of critical materials in industrial production waste with minimal consumption of hazardous acids, energy, and time was presented. The samples were first screened for valuable and hazardous elements by micro-X-ray fluorescence (XRF). Samples with considerable contents of Cs, Rb, and Aswere then prepared as slurries for the total reflection XRF (TXRF) measurement. To evaluate the TXRF procedure, a standard reference material was analyzed. As a result, Rb and Cs in concentrations up to 420 ± 70 and 1500 ± 200 mg/kg were detected in some of the waste forms. The time savings were in order of a factor of 3 when comparing the prescreening combined micro-XRF and TXRF approach to an all TXRFanalysis approach.
ABSTRACT
The toxicity, bioavailability, and mobilization of elements within the biosphere is dependent on its species. CE has emerged as a strong separation technique for elemental speciation. Conventionally, CE has been coupled with UV-vis, C4 D, PIXE (proton-induced X-ray emission), and ICP-MS. UV-vis and C4 D are not elemental sensitive detection methods, PIXE requires the etching of the detection window resulting in a very brittle capillary, and ICP-MS is an expensive large footprint instrument. Here, we aim to develop an elemental specific detector, XRF (X-ray fluorescence spectrometry), for use with CE. A custom-built micro-XRF was tested and static LODs were determined for 19 elements (Ca-U) with both unmodified (20-926 ppm) and modified capillaries (20-291 ppm). A custom-built CE was combined with the micro-XRF and separation of Ca2+ and Co2+ was obtained. Sr2+ coeluted with Ca2+ in the mixture, but because of the elemental sensitivity of XRF, the Sr and Ca signals could be separated. After successful testing of the micro-XRF, the feasibility of using a low-cost X-ray source and detector was tested. Even lower LODs were obtained for Ga and Rb, showing the feasibility of a smaller, low-cost XRF unit as an elemental specific detector. However, the buffer selection that can be conveniently used with XRF is currently limited due to capillary corrosion, likely correlated to radiolysis.
