Use this URL to cite or link to this record in EThOS:
Title: The development of composite membranes via polymer coatings for organic solvent nanofiltration
Author: Cook, Marcus
ISNI:       0000 0004 7658 6482
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2018
Availability of Full Text:
Access from EThOS:
Access from Institution:
This thesis offers a comprehensive study into the development of composite membranes for Organic Solvent Nanofiltration via solvent-free coating of epoxysilicones, and dip coating of polymers of intrinsic microporosity. Firstly, two different ultrafiltration membranes are fabricated from polyacrylonitrile and a polyetherimide and optimised to similar nominal pore sizes. These are both then employed as support membranes for the formation of Thin Film Composite membranes from coating epoxysilicones or PIMs. Minor changes in the coating solvent mixture for the PIMs enabled the formation of uniform coatings of < 500 nm thickness. The separation performance of three PIM variants was found to be fairly similar, with each displaying a Molecular Weight Cut Off of 500-800 g mol-1 in various test solvents. In parallel, a solvent free coating approach was developed to fabricate epoxysilicone TFC membranes. In this case, the support membrane was found to be a key factor in the separation performance of the composite membrane. Since the PDMS based TFC membranes were formed from cationically curable epoxysilicones, residual pendant amines in the support membrane were found to be inhibitory to the crosslinking of the cycloaliphatic epoxy. Intrusion of the epoxysilicone into the support membrane was also verified by SEM/EDS. Epoxysilicone TFC membranes were then used in a three stage membrane cascade to mimic a light/heavy key separation, whereby attention is drawn to the engineering analysis of the membrane cascade. Finally, nanofiltration of azeotropic mixtures of toluene/alcohol was conducted using the epoxysilicone composite membranes. For a system of toluene/n-butanol, the separation was observed to go through a maximum at the azeotropic composition, suggesting an integrated distillation and membrane process may be feasible for this mixture. The Flory-Huggins ternary equations were integrated into the solution diffusion transport model to enable estimations of how these types of mixtures may separate through dense, non porous membranes.
Supervisor: Livingston, Andrew Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral