| Abstract: | Graphene oxide (GO) is one of the most interesting carbon nanomaterials that have been used
in analytical chemistry in recent years. Such an interest in GO can be explained by its
excellent adsorptive properties, which result from its large surface area and presence
of functional groups containing oxygen atoms, i.e. carbonyl, hydroxyl and epoxy ones.
Oxygen-functional groups on the surface of GO are responsible for metal ions complexation.
Unfortunately, GO is not selective toward metal ions. Therefore, in order to improve the
selectivity of GO, it is necessary to modify its structure.
The aim of the PhD thesis was the synthesis of chemically modified GO that can be used
for the development of new analytical procedures enabling determination of metal ions. New
adsorbents such as GO-SH, GO-1N, GO-2N i GO-3N were prepared through grafting silanes
containing thiol and different number of amino groups on the GO surface, respectively. They
were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy
and X-ray fluorescence spectrometry. In the next step adsorptive properties of nanomaterials
were investigated. The parameters such as pH, sample volume and contact time between
analytes and adsorbent were evaluated. Then, the maximum adsorption capacity of the GO
derivatives were determined.
Due to excellent dispersibility of developed GO-based nanomaterials in water, they were
applied in dispersive micro-solid phase extraction (DMSPE) for preconcentration of metal
ions. Total-reflection X-ray fluorescence spectrometry (TXRF) was used for determination
of Co(II), Ni(II), Cu(II), As(III), Cd(II) and Pb(II) ions adsorbed on the GO-SH surface.
The proposed procedure allows achieving low detection limits ranging from 0.054–0.11 ng
mL-1. The GO-1N was applied for preconcentration of Pb(II) and Cr(VI) ions. In that case
electrothermal atomic absorption spectrometry (ET–AAS) and energy-dispersive X-ray
fluorescence spectrometry (EDXRF) were used as detection techniques which allowed to
obtain very low detection limits, i.e. 0.009 and 0.17 ng mL-1 for Pb(II) and Cr(VI),
respectively. The developed methods were successfully applied for the analysis of lake, river,
tap and sea water. |