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oai:bura.brunel.ac.uk:2438/53722014-11-01T12:21:58Zcom_2438_58com_2438_23col_2438_4327col_2438_3672

Sermon, PA Holland, Kirsten Jane 2011-06-22T12:09:01Z 2011-06-22T12:09:01Z 1998 http://bura.brunel.ac.uk/handle/2438/5372 This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Surfactants from the 'Triton' range, manufactured by Rohm and Haas, Germany, were used to study the adsorptive behaviour of non-ionic surfactants (of the alkyl polyoxyethylene type) from aqueous solution onto mineral oxide surfaces. The oligomeric distributions of the surfactants were characterised using the HPLC technique. Two gradients were used: a normal phase gradient was used to study the surfactants from non-aqueous solution; an unusual gradient, which could not be definitively categorised as either normal or reversed phase and which was developed at Brunel, was used to analyse surfactants directly from aqueous solution. Quartz was used as a model mineral oxide surface. The quartz surface was characterised using a range of techniques: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, X-ray fluorescence -analysis, Fourier transform-infra red spectroscopy and BET analysis. It was found that washing the quartz with concentrated HCI removed any calcium ions present on the surface and also removed 02- ions. Calcining the sample removed carbonaceous materials from the surface and also caused a decrease in the surface area. The quartz was shown to be non-porous by SEM and BET analysis. The adsorption experiments for this study were carried out using a simple tumbling method for which known ratios of surfactant in aqueous solution and quartz silica were mixed together for a known length of time. The amounts of surfactant present were measured using ultra-violet analysis and the HPLC techniques mentioned above. It was found that the smallest oligomers were adsorbed the most. An addition of salt to the system caused an overall increase in adsorption of the bulk surfactant, and increase in temperature caused an initial decrease in adsorbed amounts before the plateau of the isotherm and a final increase in bulk adsorption at the plateau of the isotherm. The oligomeric adsorption generally appeared to mirror the behaviour of the bulk surfactant. Atomic force microscopy (AFM), dynamic light and neutron scattering studies were used to analyse the character of the adsorbed surfactant layer. It was shown that the layer reached a finite thickness that corresponded to a bilayer of adsorbed surfactant. According to AFM data, this value of thickness was not consistent over the whole of the quartz surface. Submitted by Otue Ekong (lbsrooe@brunel.ac.uk) on 2011-06-22T12:08:43Z No. of bitstreams: 1 FulltextThesis.pdf: 13088678 bytes, checksum: 8812d8482a00bc97bdf17b52b654ecd8 (MD5) Approved for entry into archive by Otue Ekong(lbsrooe@brunel.ac.uk) on 2011-06-22T12:09:01Z (GMT) No. of bitstreams: 1 FulltextThesis.pdf: 13088678 bytes, checksum: 8812d8482a00bc97bdf17b52b654ecd8 (MD5) Made available in DSpace on 2011-06-22T12:09:01Z (GMT). No. of bitstreams: 1 FulltextThesis.pdf: 13088678 bytes, checksum: 8812d8482a00bc97bdf17b52b654ecd8 (MD5) EU en http://bura.brunel.ac.uk/bitstream/2438/5372/1/FulltextThesis.pdf Triton range Rohm and Haas Alkyl polyoxyethylene Oligomeric distributions HPLC technique The adsorptive properties of oligomeric, non-ionic surfactants from aqueous solution Thesis