Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556719
Title: Optimising surfactants for CO2
Author: Mohamed, Azmi
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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Abstract:
With regard to CO2-based processing and handling technologies, research into optimising COrphilic surfactant design is especially important. Here, surfactant structure design is focused on anionic surfactant analogues of Aerosol-OT (sodium bis (2-ethylhexyl) sulfosuccinate). The surfactants were systematically synthesised with modification centred on four strategies including (1) alkyl chain type (2) introduction of a third chain (3) counterion type and (4) surfactant template. The work presented in this thesis has aimed to investigate the relationship between the architecture and the properties (aggregate formation and interfacial activity) of AOT analogue in water and water-in-C02 (wlc) microemulsion. The surfactants have been investigated by a range of techniques including high-pressure phase behaviour, small-angle neutron scattering (SANS) and air-water (alw) surface tension measurements. The results show fluorination is a crucial factor influencing AOT surfactant analogue compatibility with CO2• The presence of fluorine in the surfactant chemical structure gives rise to an optimum interfacial packing density needed to promote favourable interactions with CO2• On the other hand, CO2- philicity of hydrocarbon surfactants can be enhanced by introducing a third chain as well as terminal methyl groups. However, despite low cost and being environmentally friendly, a major limitation of these hydrocarbon surfactants is inability to disperse water in the CO2 continuous phase. The results also highlight the challenges in controlling the CO2-philicity of hydrocarbon surfactants by changing bulky tetrapropylammonium (TPA) counterion and hydroxyaluminium disoap headgroup. It has now been established that both modifications are detrimental to CO2 compatibility. Here, a novel hybrid surfactant, with one F-chain and another H-chain, was synthesised where attention has been paid to minimizing the fluorine content while retaining' an acceptable level of COrphilicity. The work has advanced the understanding of how CO2-philicity of AOT analogues can be enhanced in CO2. The results obtained are beneficial for expanding CO2 industrial applications and realising its potential using the most economic and efficient CO2- philic surfactants.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.556719  DOI: Not available
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