Magister Scientiae - MSc (Chemistry) / Drinking water with high concentrations of inorganic and organic contaminants can cause
adverse health defects. Specifically methyl orange dye is an organic water contaminant that has
been known (along with others like methyl blue etc.) to have an increase in our water systems
over the past few years due to increasing demand in industrial processes. It is therefore of
utmost importance to remediate organic contaminants and ultimately enable prevention. The
contaminants can be removed by photocatalysis. Anatase TiO2 is known for its photocatalytic
degradation of environmental pollutants and photoelectro-chemical conversion of solar
energy. However its application is limited since it is a wide band gap semiconductor, (Eg = 3.2
eV). The following study deals with the enhancement of the photocatalytic properties of TiO2
for remediation of organic water contaminants. The study was carried out to produce the two
nanocomposites AgFe-TiO2 and AgFe-TiO2-rGO photocatalyst which purpose is to be cheap
and easy to apply, with improved (fast and effective) photocatalytic degradation of methyl
orange. The main objective was to decrease the band gap and to introduce intra-band gap states
to absorb visible light. Modification of the TiO2 with small bandgap semiconductor, graphene
and Ag- Fe nanoalloy reduced the bandgap energy for visible light absorption and
photocatalytic degradation of methyl orange dye. The two composites were synthesised using
sonication and chemical synthesis methods. A photocatalytic study (degradation of methyl
orange dye) was carried out using a system incorporating an UV lamp source to determine the
degradation of methyl orange catalysed by the synthesised photocatalysts AgFe-TiO2-rGO and
AgFe-TiO2 along with UV-vis Spectroscopy. Morphological studies were carried out using
HRSEM and HRTEM which determined the spherical agglomerated nature of AgFe-TiO2 and
the sheet-like nature of AgFe-TiO2-rGO containing spherical agglomerants but that also
contained pockets formed by the sheets of the rGO. XRD served as confirmation of the phase
of TiO2 in both composites to be anatase. Analysis confirmed the formation and elemental
determination of both composites. It was observed that the Band gap of TiO2 degussa decreased
from 2.94 eV to 2.77 eV in the composite AgFe-TiO2. The photocatalytic reactivity of AgFe-
TiO2 was an improvement from TiO2 and AgFe-TiO2-rGO based on the photocatalytic study.
Therefore concluding that AgFe-TiO2 was the best catalyst to convert the dye (Orange II) into free
radicals and ultimately remove the contaminant from the water compared to AgFe-TiO2-rGO.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uwc/oai:etd.uwc.ac.za:11394/6274 |
| Date | January 2018 |
| Creators | Sass, Danielle |
| Contributors | Ross, Natasha, Iwuoha, Emmanuel |
| Publisher | University of the Western Cape |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Rights | University of the Western Cape |
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