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# Magnetic adsorbents displaying switchable ion-exchange behaviour

Willett, Thomas Clifford (2009)
Ph.D. thesis, University of Birmingham.

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## Abstract

Magnetic bioseparations based on non-porous adsorbents offer a low-fouling alternative to the porous materials required by conventional adsorbent separation techniques. Interest in magnetic bioseparations has been limited by the high cost of suitable magnetic absorbents. In this study a variety of techniques - including Ce(IV) initiation, surface ATRP and sulfonyl activation – were used to graft ion-exchanging polyelectrolyte surfaces on low cost non-porous polyvinyl alcohol-magnetite supports. Grafting of poly(2-vinyl pyridine) and poly(methacrylic acid) was fully characterised using solid and liquid state FTIR. Dense polyelectrolyte layers were seen, with Ce(IV) grafted layers accounting for up to 49% of grafted support mass. Values for ATRP and tresyl activations were 41% and 25% of support mass respectively. These included layers which correspond to the brush regime (2R$$_f$$/D > 8), as determined by Flory Radius calculations. The above matrices were subsequently analysed with bind and elute studies using a model mixture of acidic and basic proteins. Switchable ion-exchange behaviour was demonstrated, with anion binding capacity >25 mg/g support at pH 5 and cation binding >25 mg/g seen for Ce(IV) grafted supports. Improved elution by pH was also seen, with up to 73% of bound lysozyme removed during a single elution at pH 5.

Type of Work: Ph.D. thesis. Thomas, Owen and Theodossiou, Eirini Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Chemical Engineering TP Chemical technology University of Birmingham 507
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