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Title: Development of charged membranes : synthesis, characterisation and application
Author: Yin, H. B.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2002
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The main objective of this work was to investigate the preparation, characterisation and application of a group of charged ultrafiltration/nanofiltration (UF/NF) membranes. The study was mainly undertaken on the polysulfone (PSU)/sulfonated poly(ether ether ketone) (SPEEK)/N-methyl-2-pyrrolidinone system. The addition of a small amount of SPEEK, in the range of 0.5-5 wt.%, in the polymer blend gave rise to a class of UF/NF charged SPEEK/PSU membranes. All charged membranes had substantially higher water flux, salt rejection, porosity and greatly reduced particle adhesion compared to the PSU base membrane. Membranes with 5 wt.% SPEEK demonstrated excellent overall properties. The application of such charged membranes in surface water treatment has been investigated through a study of their ability to remove humic acid (HA) from a model water, in comparison with two commercial membranes. The charged membranes showed excellent retention of HA and very high flux. Their high charges gave rise to critical fluxes for deposition. HA deposits forming on the charged membranes had a loose structure, as visualised by atomic force microscopy. The effect of SPEEK in the charged membrane formation was further investigated. Thermodynamic stability of the casting solutions decreased while solution viscosity increased with the increase of SPEEK content, especially at higher base polymer (PSU) concentrations. "Polyelectrolyte behaviour" - a peak in reduced viscosity in the SPEEK/PSU system at the dilute concentrations, was observed for the first time in the membrane forming systems. A correlation between these effects of SPEEK and in the final membrane structure and properties was found. Other important process parameters, such as, polymer concentrations, choice of solvents and choice of base polymers also showed a great influence on the formation of charged membranes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available