M-Tech. (Department of Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology. / The commercial flake graphite was prepared into functionalized graphite oxide (GO) by adopted chemical treatment. After the exfoliation and intercalation of graphite into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate in a microwave at 35 oC for two hours. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, Ultra-violet visible (UV-vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman microscopy and magnified optical microscopy that confirm the oxidation of graphite and reduction of graphene oxide into graphene sheets. Carbon nanomaterials were synthesized from Co-Sn, Co-Sr and Co-Zn as catalysts supported on Al2O3, CaCO3 and MgO. The as-prepared nanomaterials were characterized by thermogravimetric and derivative thermogravimetric analysis (TGA & DTA), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and the transmission electron microscopy. The intensity ratios (ID/IG) of the D- and G- bands were found to be the same that is averagely at 0.83. The TGA & DTA curves have shown Co-Sn/Al had significant weight loss, Co-Sr/Mg weight loss and decomposition, Co-Sr/Al decomposition and Co-Zn/Mg weight loss. However these weight losses were not significant. The EDS analysis showed all elements which took part in the reaction confirming the success of each synthesis. The SEM images show carbon nanotubes only on samples that have been synthesized on MgO as confirmed by TEM images. Finally the XRD showed some characteristic peaks at desired peaks except that they were other peaks attributed to impurities and armophous carbon. It was also observed that Co-Sn/Ca and Co-Sn/Mg XRD curves showed broad peaks at theta = 24.3o & 42.6o and theta = 23.9o & 43.1o respectively which are lattice structure characteristic peaks.

This study was made to increase the understanding of how heavy metals in the aqueous phase are removed at low initial concentrations in different pH and Eh values. The reaction that has been studied is mainly hydroxide precipitation and adsorption in a condensate treatment. In the study, data from one of Vattenfalls waste incinerators was analysed and the results from the data were then compared to previous studies. To increase the understanding, modelling of the heavy metals behaviour in the given concentrations was then made with Medusa and PHREEQC. The heavy metals that were analysed were Sb, As, Pb, Zn, Cr, and Cd. The low initial concentration that vary between 36.1-23600 μg/l complicates the removal process because it corresponds in a low driving force and the results are hard to compare to other studies since the initial concentrations vary between 10-100 mg/l. From the modelling and the measurement data it can be seen that Pb, Zn, Cr, and Cd was removed by hydroxide precipitation at pH 10. According to the speciation calculations, the dominant species at this pH are Pb(OH) 2 , Cd(OH)2, Zn(OH)2 and Cr(OH)3. For arsenic a clear conclusion could not be drawn from the modelling and the measurement data because of low precision. Due to the limited thermodynamic parameters of antimony in comparison with other heavy metals in the database of Medusa and PHREEQC, the modelling of antimony behaviour in condensate treatment has relatively larger uncertainty is low. The modelling results show that the main species in acidic solutions for antimony is Sb(OH)3 and in basic solutions Sb(OH)-6. Further investigation for antimony in needed for a clear conclusions to be drawn