Abstract
M.Sc. (Chemistry)
The presence of toxic trace metals in the environment has been considered as a global problem due to their increased concentration and toxicity. Exposure to these toxic trace metals can result in chronic diseases and organ failures. However, the level of these toxic trace metals in the environment must be monitored. Some of these metals are known to exist in ultra-trace levels in the environment and that makes it a challenge to directly quantify using analytical techniques like ICP-OES, ICP-MS and AAS, among others. Therefore, the development of new, simple, and efficient methods for the preconcentration and determination of these trace metals is important. For these methods to successfully work a versatile adsorbent is needed for the preconcentration and determination of these toxic trace metals. Therefore, the aim of this study was to synthesize ion imprinted polymers (IIPs) as an adsorbent for the preconcentration of toxic metal ions in the environment. IIPs were used as choice of adsorbent because of their high stability, ease of synthesis, high selectivity towards the target metal ions and they can be used in cases where more than one metal ion exist in the same sample matrix by retaining specific recognition of each metal ion. The morphology and structural properties the adsorbents were investigated using Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction spectroscopy (XRD). Inductively couple plasma optical emission spectroscopy was used for the detection of the toxic metal ions. The first objective was to synthesize magnetic-ion imprinted polymer (Fe3O4@SiO2@CNFs) nanocomposite for the extraction and preconcentration of Sb(III) ions in environmental samples. Ultrasonic-assisted magnetic solid phase extraction (UAMSPE) was developed as preconcentration method. Factors affecting the extraction efficiency of the nanocomposite were investigated using response surface methodology. Under optimised conditions the analytical performance of the nanocomposite was investigated, and their linear dynamic range (LDR) ranged from 0.44-100 µg L-1 with a correlation coefficient of 0.9976. The limits of detection (LOD) and quantification (LOQ) of the UA-MSPE/ICP-OES procedure were 0.13 µg L-1 and 0.44 µg L-1 , respectively. The adsorbent showed good precision in terms of repeatability and reproducibility...