Abstract
M.Sc. (Chemistry)
With an increased need for clean water in South Africa, there is a need to find more techniques for water purification. The improved standards required by the World Health Organization (WHO) has led to a quest of technological advancements in finding more effective and cost friendly techniques for water purification. The use of nanoparticles (semiconductor metal oxides) has emerged as a promising approach to purify water, removing pollutants from water to low concentrations that meet the WHO standards.
Tungsten trioxide (WO3) is considered as one of the best semiconductor photocatalyst capable of photodegradading organic compounds. Pristine WO3 is, however not capable of photoreducing inorganic substances in water. Therefore, this work presents a modified WO3 to improve the photocatalytic activity in the photoreduction of Cr(VI) and Cu(II) in wastewater. The modification was carried out through doping with magnesium and yttrium metals respectively. Although these aforementioned dopant metals come costly, the synthesis routes and efficiency of the doped WO3 in the reduction of Cr(VI) and Cu(II) is worthwhile.
The hydrothermal method was used to synthesize WO3, Mg doped WO3 and Y doped WO3 nanoparticles. In order to understand the structure of the synthesized nanoparticles, the nanoparticles were characterized using X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), Filed emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, zeta potential, Brunauer–Emmett– Teller (BET) surface area, UV-visible spectroscopy (UV-vis), X-Ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL).
The as-synthesized materials were confirmed to be composed of crystalline monoclinic polymorphs as shown by the XRD, FTIR and Raman spectroscopy. The average crystallite size was found to be around 32 nm with an average particle strain of 0.002498. The particle sizes were found to be of 141 nm in average as confirmed by TEM. The difference in d spacing were observed for the doped nanoparticles...