Natural organic matter (NOM) is a diverse blend of decomposed animal and plant material
found in different natural water sources. Due to its large and complex structure, NOM is
difficult to both remove and characterize in water. Therefore, there is a need to separate
NOM into its components before it can be characterized. The aim of this project was to
fractionate NOM through a novel size exclusion chromatography (SEC) composite (poly
(styrene-divinyl benzene) (PS-DVB) and Polysilsesquioxane (PSQ)) packed column. Raw
and final water samples from Mid-Vaal (MV), Olifantspoort (LO), Mtwalume (MT) and
Preekstoel (P) were investigated. Poly (styrene-divinyl benzene) (PS-DVB) and
polysilsesquioxane were both synthesized and optimized at various temperatures,
compositions and time periods. An end-capping material such as hexamethyldisilizane
(HMDS) was added on the PSQ to prevent active silanol groups on the polysilsesquioxane
(PSQ) from reacting with active sites of NOM (our analyte). The E-PSQ (end-capped PSQ)
and PS-DVB materials were packed in eight different SPE cartridges first, before the
materials could be packed in the SEC column. This packing was done to check for the best mass composition of the E-PSQ and PS-DVB. From the obtained SPE results, both the EPSQ
and PS-DVB were packed in one SEC/GPC column at a ratio of 1:1 in order to form
the composite hybrid material. The packed SEC column was connected to an HPLC
instrument and various column efficiency tests were evaluated. The results for the test of
interactions with acidic compounds implied that the column can be used for the acidic
analytes such as those forming NOM composition (humic acids, fulvic acids) and the
column had minimum silanol groups. For hydrophobic interactions the stationary phase
strength was different to that of the commercial columns and it could selectively elute
molecules based on their different masses. The steric selectivity test showed that the
stationary phase could separate and distinguish between molecules with similar
hydrophobicity and structure but different shapes (o-terphenyl and triphenylene). The
Hydrogen bonding capacity (HBC) test showed that the column had minimum silanol
groups and the end-capping was successful on the E-PSQ.
After fractionation of all the water samples, the MT raw showed NOM peaks around 1.8
mins, 3.4 mins and 5.3, and the final showed NOM peaks around 1.8 mins and 5.5 mins.
The Mid-Vaal (MV) raw and final samples shows NOM peaks at around 1.8 mins and 6
mins. The Preekstoel (P) final water had one NOM peak at around 1.8 mins and raw
samples had two NOM peaks around 1.8 mins and 6 mins. / Chemistry / M. Sc. (Chemistry)
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/23999 |
| Date | 06 1900 |
| Creators | Bopape, Dineo Anna |
| Contributors | Nkambule, T. I., Msagati, Titus A. M., Mamba, B. B.(Bhekie Brilliance) |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | 1 online resources (xix, 120 pages) : illustrations (some color), graphs |
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