Electrochemistry and separation of transition metals with biodegradable ligands

Katata, L. M. (2001-12)

Thesis (MScEng) -- Stellenbosch University , 2001.

Thesis

ENGLISH ABSTRACT: The electrochemical analysis of selected metal ions with the newly biodegradable chelating agents, lminodisuccinic acid (IDS) and Polyaspartic acid (PASP) was performed by cyclic voltammetry using a thin mercury film glassy carbon microelectrode. IDS and PASP are of interest from an environmental perspective. They were introduced as alternatives to chelants and dispersants. The thermodynamic stability constants of these selected metal complexes were determined by cyclic voltammetry (CV). A comparison with similar data obtained using potentiometric methods shows a good correlation between the two methods. This reaffirms that CV is a useful and facile means for evaluating metal-ligand complex thermodynamic data. Furthermore, our results were used to validate the predicted models obtained using an Equilibrium Speciation model JESS program. Capillary Electrophoresis (CE) was used to separate metal-IDS and metal-PASP complexes at different pH's. The separation of these chelates was achieved within 7 minutes. The obtained results were compared with speciation and a reasonable agreement was observed, although the separation ofmetal-PASP showed poor broad peaks.

AFRIKAANSE OPSOMMING: Die elektrochemiese analise van geselekteerde metaal-ione met nuwe biodegredeerbare chelate, Iminodisuksien suur (IDS) en Polyaspartiese suur was gedoen met sikliese voltametrie deur gebruik te maak van 'n dun laag kwik glasagtige koolstof mikroelektrode. Vanaf'n omgewingsstandpunt is IDS en PASP van belang. Hulle was voorgestel as alternatiewe vir chelate en verspreidingsagente. Die termodinamies stabiliteits konstantes van hierdie uitgesoekte metal komplekse was bepaal deur middel van sikliese voltametrie (CV). 'n Vergelyking met soortgelyke data, wat met potensiometriese metodes bepaal was, dui 'n goeie korrelasie aan tussen die twee metodes bepaal was. Dit bevestig die feit dat CV 'n bruikbare en maklike manier is om metal ligand komplekse se termodiniese data te evalueer. Die resultate was ook gebruik om die voorspelde model, wat verkry was deur gebruik te maak van "Equilibrium Speciation model JESS program, te bevestig. Kapillere elektroforese (CE) was gebruik om metal-IDS en metal-PASP komplekse by verskillende pH's te skei. Die skeiding van hierdie chelate was binne sewe minute verkry. Hierdie resultate was vergelyk met die spesiasie data en 'n aanvaarbare ooreenstemming was waargeneem, alhoewel die skeiding van die Metaal-PASP swak pieke toon.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52257
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