Investigating the sorption phenomena of free fatty acids using the quartz crystal microbalance
File(s)
Author(s)
Seanneng, Kebonyetsala Aobakwe Laurel
Type
Thesis
Abstract
Fatbergs have become an increasing problem with the increase in demand and use of products that contain fats oil and grease (FOG) formed when FOG and sanitary products lump together forming huge masses in sewers thus creating problems such as sewer overflows. This poses a danger as sewage making its way into water streams contaminates water. To address the problem, the adsorption of fatty acids identified in sewer systems i.e. palmitic acid , oleic acid and linoleic acid by He et al. (2013) onto polystyrene, aluminium oxide, and silicon dioxide was investigated using Quartz crystal microbalance with dissipation (QCMD). The emphasise of the study was to minimize the impact of the FOG deposits by prevention hence the study focuses exclusively of adsorption of free fatty acids (FFA).
Pseudo first order and pseudo second order models revealed that experimental results were a good fit for the PSO model with R2 > 0.93 thereby suggesting that the fatty acids chemically adsorbed to the sensors and formed a monolayer. Chemical adsorption was confirmed by Xray photoelectron spectroscopy (XPS). Competitive adsorption studies revealed that palmitic acid introduced rigidity to the adlayer and the extent of this dependent on its position in the sequence. Linoleic acid adsorbed in an extended state while oleic acid adsorbed parallel to the quartz sensors (Lundgren et al., 2006). This effect was affected by the position of linoleic acid and oleic acid in the sequence thus resulting in different conformational changes within the adlayers. The effect of pH determined that adsorption of the FFA was highest around the pKa values of 9.85, 9.24 and 8.6 respectively with palmitic acid forming the thickest layer. Calculation of the thermodynamic parameters revealed that the adsorption of the fatty acids onto a gold sensor was an endothermic process with a great degree of spontaneity.
Pseudo first order and pseudo second order models revealed that experimental results were a good fit for the PSO model with R2 > 0.93 thereby suggesting that the fatty acids chemically adsorbed to the sensors and formed a monolayer. Chemical adsorption was confirmed by Xray photoelectron spectroscopy (XPS). Competitive adsorption studies revealed that palmitic acid introduced rigidity to the adlayer and the extent of this dependent on its position in the sequence. Linoleic acid adsorbed in an extended state while oleic acid adsorbed parallel to the quartz sensors (Lundgren et al., 2006). This effect was affected by the position of linoleic acid and oleic acid in the sequence thus resulting in different conformational changes within the adlayers. The effect of pH determined that adsorption of the FFA was highest around the pKa values of 9.85, 9.24 and 8.6 respectively with palmitic acid forming the thickest layer. Calculation of the thermodynamic parameters revealed that the adsorption of the fatty acids onto a gold sensor was an endothermic process with a great degree of spontaneity.
Version
Open Access
Date Issued
2024-05-24
Date Awarded
2026-03-01
Copyright Statement
Attribution-Non Commercial-No Derivatives 4.0 International Licence (CC BY-NC-ND)
Advisor
Heng, Jerry
Sponsor
Government of Botswana
Publisher Department
Department of Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)