Graphene Oxide Decorated with Cerium(IV) Oxide in Determination of Ultratrace Metal Ions and Speciation of Selenium

Graphene oxide decorated with cerium(IV) oxide (GO/CeO 2 ) was synthesized and applied in adsorption of several metal ions such as As(III), As(V), Se(IV), Cu(II), and Pb(II) from aqueous samples. The important feature of GO/CeO 2 nanocomposite is also its selectivity toward selenite in the presence of selenate. The structure of GO/CeO 2 has been proven by microscopic and spectroscopic techniques. The maximum adsorption capacities of GO/CeO 2 calculated by Langmuir model toward arsenic, selenium, copper, and lead ions are between 6 and 30 mg g –1 . An interesting feature of this adsorbent is its excellent dispersibility in water. Thus, GO/CeO 2 nanocomposite is ideal for fast and simple determination of heavy metal ions using dispersive microsolid phase extraction (DMSPE). Moreover, coupling DMSPE with energy-dispersive X-ray fluorescence spectrometry (EDXRF) is extremely beneficial because it allows direct analysis of adsorbent. Thus, the analyte elution step, as needed in many analytical techniques, was obviated. The influence of sample volume and the sorption time as well as the influence of foreign ions and humic acid on the recovery of determined elements are discussed in the paper. The results showed that developed methodology provided low limits of detection (0.07–0.17 μg/L) and good precision (RSD < 4%). The GO/CeO 2 nanocomposite was applied to analysis of real water samples and certified reference materials (CRM) groundwater (BCR-610) and pig kidney (ERM-BB186).