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Title: The characterisation of derivatised polyacrylonitrile fibres and their use in the recovery of metal ions
Author: Mathews, R. G.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1998
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This study comprises characterization of fibres based on derivatised polyacrylonitrile, and investigation of their use as ion-exchange media. Physico-chemical and mechanical properties of fibres and fabrics made therefrom were determined. Dry fibres were non-porous, of high specific surface area (>105m2/m3), with densities (1.35-1.6 g/cm3 higher than those of typical particulate exchangers (PEs). Fibres absorbed less water (40-60 vol%), than comparable PEs (100 vol%). Mechanical properties of fibres were affected by derivatisation and absorption of water. Fabrics were possessed low effective pore radii (<10-5m) and high voidages (>0.7), and formed compressible beds whose characteristics were subject to control by external pressure. Effective exchange capacities of fibres fell within the range 0-4.5mmol/g, reaching maximum for fibre Actilex A301, (~ 45% of that of a PE incorporating similar active groups). This capacity varied as a function of pH, in a manner consistent with weak-acid behaviour. This fibre possessed an effective capacity for zinc at neutral pH of ~ 1.6mmol(Zn)/g. A three-stage recovery and regeneration cycle was found to effect repeatable and reproducible behaviour. Thin beds of A301 (<25mm), used to absorb zinc in an ion-exchange column, removed all influent zinc at very high flowrates, (>1000 bed volumes (BV)/hr). Transfer of zinc into exchange media was simulated using a model involving radial diffusion during axial advection and diffusion into the media, to produce breakout curves for beds, which were in reasonable agreement with experimental data. Ionic diffusivities within fibres were estimated from comparison of the model with experimental data and found to be less than those in PEs. Various comparisons of likely performance of beds of fibres and PEs demonstrated that fibrous beds have some advantages over those of PEs. The potential exploitation of these in continuous forms of fabric (and processes) are considered.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available