Sensitive determination of uranium using ß-cyclodextrin modified graphene oxide and X-ray fluorescence techniques: EDXRF and TXRF.

ABSTRACT

ß-cyclodextrin/graphene oxide (GO-ß-CD) was applied for dispersive micro-solid phase extraction (DMSPE) of uranyl ions (UO22+) from water samples and their determination by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The structure of GO-ß-CD was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The results of batch adsorption experiment indicate that the maximum recoveries for UO22+ ions are observed at pH 4.5. The Langmuir isotherm model fits the adsorption data, which stands for the chemisorption mechanism. The obtained adsorption capacity of 87.7 mg g-1 indicates a great potential of the synthesized adsorbent in the UO22+ ions preconcentration. The GO-ß-CD exhibits high resistance to high ionic strength (up to 2 mol L-1), indicating that high salinity samples can be treated with the evaluated preconcentration procedure. The obtained limit of detection values were 0.40 µg L-1 for the EDXRF and only 0.014 µg L-1 for TXRF analysis. The accuracy of the method was verified by analyzing certified reference material (spring water NIST-SRM 1640a) and spiked water samples (mineral, lake, river, and artificial sea water).