An ion imprinted polymer for the determination of Ni (II) ions from mine tailing samples
- Authors: Rammika, Modise
- Date: 2011
- Subjects: Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4323 , http://hdl.handle.net/10962/d1004981 , Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Description: A Ni(II)-dimethylglyoxime ion imprinted polymer {Ni(II)-DMG IIP} was synthesized by the trapping method using the bulk polymerisation format. The structures of the imprinted and non-imprinted polymer were evaluated by infrared spectroscopy and the morphology was observed by scanning electron microscopy. The Ni(II)-DMG IIP was optimised for pH, mass, time and by the uniform design experimental method for the molar ratios of monomer to crosslinker to porogen and template to ligands as well as keeping these parameters constant and varying the quantities of initiator, 2,2'-azobisisobutyronitrile (AIBN). The optimum pH was 8.5, optimum mass was 50 mg, optimum time was 1 min and the optimum molar ratios of crosslinker to monomer, monomer to template and nickel(II) sulfate hexahydrate (NiSO₄.6H₂O) to 4-vinylpyridine to dimethylglyoxime were found to be 3.3:1.0, 0.6:1.0 and 1.0:0.6:3.6 respectively with 30 mg and 8 mL as the optimum amounts of initiator and porogen respectively. Through this optimisation, recovery of Ni(II) was increased from 98 to 100%. Selectivity of the ion imprinted polymer was evaluated by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. Selectivity studies also confirmed that the ion imprinted polymer had very good selectivity characterised by % RSD of less than 5 %. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). The limits of detection and quantification were found to be 3x10⁻⁴ μg/mL and 9x10⁻⁴ μg/mL respectively. The method was evaluated by a custom solution of ground water certified reference material (SEP-3) and sandy soil reference material (BCR-142R) and the concentrations of Ni(II) obtained were not significantly different to the certified ones. The Ni(II)-DMG IIP was then evaluated in aqueous and soil samples where recoveries of 93 to 100% and 98 to 99% respectively were obtained with enrichment factors ranging from 2 to 18 in aqueous and 27 to 40 in soil samples. Finally, the Ni(II)-DMG IIP was used to analyse mine tailings samples and Ni(II) recovery of 99% was obtained with an enrichment factor of 2.
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- Date Issued: 2011
Dimethylglyoxime based ion-imprinted polymer for the determination of Ni(II) ions from aqueous samples
- Authors: Rammika, Modise , Darko, Godfrey , Tshentu, Zenixole R , Sewry, Joyce D , Torto, Nelson
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6590 , http://hdl.handle.net/10962/d1004173
- Description: A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was synthesised by the bulk polymerisation method. The morphology of the Ni(II)-DMG IIP and non-imprinted polymer were observed by scanning electron microscopy and the chemical structures were evaluated by infrared spectroscopy. Selectivity of the Ni(II)-DMG IIP was studied by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. The studies revealed Ni(II) recoveries ranging from 93 to 100% in aqueous solutions with minimal interference from competing ions. Enrichment factors ranged from 2 to 18 with a binding capacity of 120 μg∙g−1. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). Selectivity studies confirmed that the Ni(II)-DMG IIP had very good selectivity, characterised by %RSD of less than 5%. The limits of detection and quantification were 3x10-4 μg∙mℓ−1 and 9x10-4 μg∙mℓ−1, respectively. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3) and the concentration of Ni(II) obtained was in close agreement with the certified one. The Ni(II)-DMG IIP was successfully employed to trap Ni(II) ions from a matrix of sea, river and sewage water. It is believed that the Ni(II)-DMG IIP has potential to be used as sorbent material for pre-concentration of Ni(II) ions from aqueous solutions by solid-phase extraction.
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- Date Issued: 2011
Incorporation of Ni(II)-dimethylglyoxime ion-imprinted polymer into electrospun polysulphone nanofibre for the determination of Ni(II) ions from aqueous samples
- Authors: Rammika, Modise , Darko, Godfrey , Torto, Nelson
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6589 , http://hdl.handle.net/10962/d1004172
- Description: Ni(II)-dimethylglyoxime ion-imprinted polymer (Ni(II)-DMG IIP) was encapsulated in polysulphone and electrospun into nanofibres with diameters ranging from 406 to 854 nm. The structures of the Ni(II)-DMG encapsulated-IIP nanofibre, non-imprinted encapsulated-polymer nanofibre and polysulphone nanofibre mats were observed by scanning electron microscopy and evaluated by infrared spectroscopy. Electrospinning increased the specific surface area of the Ni(II)-DMG encapsulated-IIP nanofibre mats, as was evidenced by the low masses of the Ni(II)-DMG encapsulated-IIP nanofibre mats used. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3); the concentration of Ni(II) obtained was close to the certified one. The limit of detection was found to be 4.0x10-4 μg∙mℓ−1 while the limit of quantification was found to be 1.2x10-3 μg∙mℓ−1. The recovery of Ni(II) achieved using the Ni(II)-DMG imprinted nanofibre mats in water samples was found to range from 83 to 89%, while that of non-imprinted nanofibre mats was found to range from 59 to 65%, and that of polysulphone from 55 to 62%.
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- Date Issued: 2011